REVIEW OF ANALYTICAL WORK DONE IN 1906. - Journal of the

REVIEWS, REVIEW OF ANALYTICAL WORK DONE I N 1906. 115. l l B 6 1 OS 1)xil:s

lieceired 1)ecemliei- 1.5,

140;

In this review the only change from the plan of previous ones is that American work has been included. The writer's acknowledgment of his indebtedness t o the CIiemisches Zcntralblatt for general grouping of subjects and for abstracts is due again and is here made. He has made use occasionally also of abstracts in the Joumuls of tlic Londoqz Chewicnl Society and Societj. 01 Chemical Iiadzrsisy. General Analysis, Apficzrutus.--A new Orsat apparatus was proposed by Bendemam ( J . Gusbel., 49, 583, from %. Vru. I n g . ) for analysis of the new power gases which contain something like 304'; of carbon monoxide, 1 2 7 ~of liydrogexi and only traces of methane. '1'1~0 cuprous chloride pipettes are used, m d where considerable amounts of oxygen are to be absorbed either

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phosphorus or a second pyrogallol pipette. About 30 cc. of gas are taken for the combustion. The combustion pipette is best covered with a water jacket connected with the water mantle of the burette. Lux (Ibid., 49, 475) described the Raupp gas calorimeter a s better than the Junker. It consists chiefly of a copper cylinder whose lower part is solid, the hollow upper part carrying a thermometer divided into tenths. Under the copper body is placed a t a certain time the gas flame, whose height has been previously determined, and the time necessary for the thermometer t o rise 10' is noted. The apparatus is standardized by means of gases of known heating value, so from a table and from the measured time the heating value can be calculated. McDowall (Chem. News, 94, 104) recommended the use, instead of the ivory scale on balances, of a brass one which should move b y a horizontal screw under the box engaging a tooth attached t o the scale. After the pans are released the scale may be moved till the pointer swings equally on either side of the zero. An apparatus was described by Weimern ( J . russ. plzys.chem. Ges. 38, 228) for determining the solubility of solids in liquids. It consists essentially of two glass cylinders held together b y an oblique tubular connection projecting downward inside the lower cylinder. The liquid is saturated with the solid in the upper cylinder which has a large stirrer that is used also t o force the liquid through the side arm containing a wadding tampon and so into the weighed glass receiving vessel. The lower cylinder has an arrangement by which the cover of the weighing vessel may be placed before the vessel is removed from the cylinder. It is then weighed, the liquid evaporated, and weighed again. Combustion and Heating Value.-A good deal of work was published on the various combustion methods noted in previous reviews. Carrasco and Plancher (Gazz. chim. ital., 36 11, 492) gave more details concerning their method of internal electrical heating in the use of which priority was claimed by Morse and Gray (Am. Chem. J . , 35,451). Dennstedt (2.angew. Chem., 19, 5 1 7 ; 2.anal. Chem., 45, 26) and Dennstedt and Hassler ( J . Gasbel, 49, 45) gave more details with regard t o Dennstedt's simplified combustion method, The second of these three articles is in reply to the criticisms of Hermann which were maintained by the latter (2.anal. Chem., 45, 236). The last of the three contains the modifications of the method necessary for the analysis of coals. Holde (Ber., 39, 1615) and Holde and Schluter (Mitth. k g l . Materialpriifun~sarr~t Gross Lichteyfelde W e s t , 24, 268) gave the results of some experiments with the Dennstedt and Heraeus furnaces, mentioning a s some of thc difficulties of Dennstedt's rapid method those of obtaining the correct agreement between oxygen addition and rapidity of combustion, the occasional failure of the platinum quartz t o glow a s a criterion for the proper carrying out of the method and the necessity of constant watching. Dennstedt (Ber., 39, 1623) replied, saying t h a t the commonest error in the rapid method is the too rapid volatilization of the substance. This should be run with an oxygen current of about 60 cc. per minute instead of running the oxygen current according t o the rapidity of volatilization. Von Konek (Ibid., 39, 2263) added his favorable experiences with-the Heraeus furnace. Marek ( J . $ 7 . Chem. [ 2 ] 73, 359; 74, 2 3 7 ) recommended the use of a 5 cm. layer of copper oxide or copper oxide asbestos in combustion analyses instead of the layer of ordinary length. This proposal was criticized b y Dennstedt (Ibid., [ 2 ] 73, 570).

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REVIEIVS.

A number of methods for determining the halogens in organic compound5 were proposed. 'I'hat of Berry (Chon. .Ycx~sj94, 188) is a combination of those of Piria and Schiff (ignition with sodiuni carbonate and lime) and the thiocyanate method of \'olhard. 'Che cooled mass is dissolved in dilute nitric acid ( I : 4)> kept cool, escvsb of tenth-normal silver nitrate added, the silver halide filtered m d the filtrate titrated with tenthnorinal potassium thiocyan;tte, using :imnionium iron alum as indicator. 1L:ith substances containing iodine, sodium carbonate alone is used for the ignition. Noir ( P 1 . o ~ .i ' i i ~i i i . .Six., 22, 261) lieated the sub-stance in a nickel cruciblc with I O drops of water and pure caustic potasli on a water bath, stirring i\.itl: :I platin~iniwire, then gradually deconi~ potassiuni posed the product rritli 0 . ~ 5 IO 1 gram of i l I i ~ lpulverized permanganate, evaporated and drove out tlx precipitated carbon b!. ignition. Tlic cooled crucible was brought into a warin dilute solution of primary potassium sulphite, tlic solution acidified -(\.it11acetic acid then filtered into :i silver nitr:itc. tiolirtioii. 'I'lie silver lialitlc mas determined as usual. Or the cooled cxciI)le might lie put iiito water, the solution acidified with :icetic acid till t!ic inangnii;ite is converted into permanganic acit!, tlic latter desti-oycil wit11 h r i i i n i pcroside, the filtered solutioti iieutra lizcd ivitli priniar!, sodiuili cnrboiiate and then titrated. Robinson (ilru. ~ ' h t ' i i ! ..I., 35, ,531j rccomnicntltd :i filling of tlie coinbustion tub:. as usual witli coppvr oxide, placing also in it a cartridge filled wit11 lvatl clim!ii,itv, lila. Norse :tiid 'l'aylor's (Ihz'd.. 33, 602) arrangement for the coniblistioli of sulphi!r-hearing compowi(1s. T'aubel anti Scheuer ( C k i u . - Z f ( r . ,3 1 , 6;:) proposced to w i g h out. 0 . 2 to 0 . ~ 5 gram of substnnce in n dr!. r:cs to 2oc) cc. distilling flask, setting a separator? funnel in place in tlie neck of tlic flask. 'l'lie side arm was colinectetl with ;i 'I-ollinrd flask i!i wch 11 \vay that it did not dip into thc silver nitrate. p to ,io cc. of coiicmtrutcti sulphuric :icid were added, the stopper 01 the sepnrntor!- iimncl c.loscd, the liqiiid wmiiecl grndually and a wtak current of :iir p i . c! t11ro;lgIi t!w :ipparatus either from the beginning or a t tllr vntd of t l w ez.I>vri,iic.iit. according i o the ease with which the gitscs arc. e\.ol\~etI. Iodiiic )cis tliivcw out of the side tube by warming. To insure tlie forni:ition of d v c r iodide and not iodatc' halogell-free filter paper or metallic c0ppc-1.v;as placed in the distilling flask to increase the ;iniount of sulpliur dioxide forinetl. In the Volhard flask silver halidc 2iIlCl ~tilphiteIwre forinctl, gatliered into a beaker, trcatvtl rvitli x-atcr z t i t l nholit ~ 5 0 ec. of concc~iitratetlnitric acid, boiled till siilphiir dioxidc wis drivc.11 oiit or :ill silver siilpliite was changed to siilplmtc. diluted till the s ~ ~ l p l i x t!issolwd te siid t h e lialide determined by weighing or b>. titration oi t l x silver iii solution. Kitrogen may lie detcrniinctl a t tlic s:i.nic tiiiic.. 1li;inchi (Boil. clijii2. ,ftzr711., 45, 821) criticizccl tliis method, iiig tiiat it \vas r:ot ill gcncral usable for orhe \xporathg I liter of the \Vater to about j b i cc. (for 0.1to I gram of coppi.i-). and :idding 2 to j cc. of sulphuric acid ant1 elcctrolyzing. usitig thr. tlisii ;is anode, \\.it11 a curretit of SD,,, = 0.3 ampere for 4 hours or ol-c'r night wit11 gcntlc stirring. 'i'he cathode w n s removed without interrupting thr. ci!rrc.iit

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and dipped into boiled nitric acid. This solution was evaporated to dryness, the residue taken u p in water, put into a IOO cc. Nessler tube, filled to the mark and I O cc. of potassium sulphide solution (equal volumes of 107~ caustic potash and saturated hydrogen sulphide solutions) added. The copper sulphide color appeared and was compared with the color in a similar tube of I O cc. of the potassium sulphide solution diluted with water and standard copper sulphate solution added (0.2 cc. a t a time) till colors were the same. For I liter of water taken, I cc. of the copper sulphate solution is equivalent to a copper content of 0.2: IOOOOOO. Raschig (2. angew. Chem., 19, 334) determined sulphuric acid b y adding t o the sample one-twentieth of its volume of a concentrated benzidine solution, stirring and allowing t o stand 15 minutes. If there were no precipitate the water contained 1.5 mg. of sulphur trioxide per liter or less. The precipitate was washed by suction, using very little water, and titrated with tenth-normal sodium hydroxide ( I cc. = 4 mg. sulphur trioxide). There should be added for the benzidine loss 1.5 mg. Iron does not interfere if I to 2 cc. of a 1% hydroxylamine hydrochloride solution be added before the benzidine precipitation. Scriba (2. physik. chem. Unterricht, 19,298) stated t h a t a paper strip dipped in a solution of I gram of ferrous ammonium sulphate in 2 0 cc. of water, dried and rubbed with pulverized potassium ferricyanide will give a deep blue spot with the smallest amount of water. Volumetric.-Acree and Rrunel ( A m . Cheni. .J., 36, I 17)prepared a standard solution of hydrochloric acid by filling a clean liter flask nearly full of water, running through a single holed rubber stopper a glass tube with a long capillary reaching nearly t o the bottom of the flask, weighing this t o 0.001gram with another flask a s tare, then passing into it a current of dry hydrochloric acid gas till the increase in weight is a little more than I gram molecule. The flask is cooled t o room temperature before the last weighing. The solution is then made u p to the mark and the extra water added from a burette. A further standardization is unnecessary. Solutions of other gases obtainable dry, a s hydrobromic and hydriodic acids, hydrogen sulphide, sulphur dioxide in any solvent, may be thus prepared. They gave also an improvement over the ordinary gravimetric method for standardizing hydrochloric or sulphuric acid solutions. About 4.i~grams of twice recrystallized primary sodium carbonate are neutralized with the necessary amount of acid (using methyl orange). The end point is reached when a weak rose-red color persists after some standing in a vacuum. The solution is evaporated to dryness in a weighed platinum dish and the residue heated to constvnt weight. From the weight of the sodium chloride or sulphate and the volume or weight of solution used i t is easy t o calculate the strength of acid. The method can be used with all acids, giving sodium salts t h a t can be dried and weighed. Richardson ( J . Clzem. Ind., 26, 78) standardized sulphuric acid by neutralizing j cc. of dilute weighed acid with filtered saturated barium hydroxide solution, using phenolphthalein. The neutral solution was evaporated on the water bath and the barium sulphate ignited and weighed. Riegler (Bull. assoc. chim. sucr. dist., 24, 528) recommended ammonium triiodate [NH,H,(IO,),] as an original standardizing material. For tenth-normal solution 3.0zj grams of the salt are dissolved in IOO cc. of boiling

428

KGVIEWS.

To standardize sodium thiosulphate I gram of potassium iodide, I cc. of hydrochloric acid (d. 1.2) and I C ) cc. of the above triiodate solution and the mixture titrated as usual with thiosulphatc. ~ K € I , H 2 ( l U : Jj3 6Sa,S,O, = gSa,S,O, ij N a I 0 , t Sal - 31I2O - ~ X I ~ , l O ~The ~ . triiodate acts as a dibasic acid and so c a n l l ~ u. x d directly for alkalimetry with luteol, Congo red or diazonitraniliiieguaiacol as indicator. Thc triiodate neutralized by sodium hydroxide is 110 longer affectcd by sodium thiosulphate so the base to be tleteriiiined can tic treated with a n excess of triiodate and the escess titrated back with thiosulpliatr. Standardization of tenth-normal acid ilia?- also he c+Tected gas \-olunietrically by letting the triiodate act on hydrazine sulphatc and dctermining the nitrogen ( Z . aitnl. (-.hew., 42, 6 7 7 ) . \\'agner, Rink and Schultze (Chem-Ztg., 30, I 181) suggested the second method of -1cree and Hrunel for the standardization of acids and bases. 'l'h stated also t h a t wherc there are tables showing thc relation lictweeii raction and concentration the Zeiss immersion rcfractoincter may lie uscd t o determine yuantitatively the reaction product. 'rhcy gave a tahle for the relation between refraction and concentration of nitric acid. =Ihlum (Proc. Chein. SOC.,2 2 , 0 3 ; J . ~ ' I z c m Soc.., . 89, 470) gave a volumetric determination of free acid in the presence of iron salts, the iron being precipitated with monosodium phosphatc, tlie phosphate filtered out and the filtrate titrated with sodiuiii hydroxide. The acid foriiicd as a result of the iron precipitation, for example, I;c,Cl, 2SaIl2P0., = 2I;cP(I, 1. 2NaC1 $- 4HC1, is corrected for. Iiupp ( Z . a d . ChcijL., 45, 6S7) stated t h a t permanganate oxidations run inore rapidly and vigorously in alkaline than in acid solution, hencc i t is advisalile in soiiie cases t o oxidize in alkaline solution, then t o acidif\- and titrate back the excess of perinanganate according t o lcaschig (Bci., 38, 391 I ) . 1;orriiic. and nitrous acids are cascs given as cxainples. Tlic forixatc solution is v-arincd in a glass stoppcrcd flask with considerable excess of pcriiianganate standardized against sodium thiosulpl-late and with 0.5 graiii of pure dry sodium carbonate for I j to j o iiiinutes on tlie water bath, diluted after cooling with about 75 cc. of x;ltcr, 2 5 cc. of dilute sulphuric acid are added and I t o 2 grains of potassium iodide, tlicii the liberated iodine is titrated with tenth-noriiial tliiosulphate (I ec. : = o.0023 gram of formic acid = 0.0023 grain of nitrous acid anion). Brandt (Z. anal. C'iiein., 45, 95) iound that the violet color of diphenylcarbohydrazide (observed by Cazeneuve [rhein.-%&., 24, 684 ; Bull. SOC. cltim. [j]2 5 , 7581) could be used to detect the end point of the bichrotilate iron titration if a suilicient amount of hydrochloric acid were present with the manganese sulphate solution containing phosphoric acid of the Reinhartl method. There should be a t least 60 t o Yo cc. of 11)-drochloric acid [d. I . 121 atlded to I. j liters of water containing 100 cc. of the rnaiiganese solution (6 kg. of sulphate, 33 liters of dilute sulphuric acid [ I : 31 and 3 liters of phosphoric acid [d. 1.71 dilutctl to Go liters), the iron solution and thv indicator (ahout cc. of O . I ? / ~ solution). 'Clieii on titrating a rcd-violet color i.; ol)taincd, bcco:iiing a iniscd color as the grccn chroniiurii salt increases till finally :I sharp change to purc greon is ottnincd a t the end. Without thc acid the decoiripositioii of the coloring inalter is too eiicrgctic and takes place ljcforc thc iron is oxidizcd. Tron ii; aiiiounts l e s ~than water and this diluted to

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40 cc. of water are put into a l h s k with

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resent, and tlic tin precipitated as above. In the tin filtrate other ii:ctals were reii:o\wI with ammonia and anirnonium sulphidc and the antiitiony precipitated 11y acetic acid. Carbon, Boron, .szbiron.-!lupperk (THIS JOUKN.\I,, 28, 858) gal-c a \-oluriietric method for the determination of carbon in iron :mcl steel which rests on the titration of barium hydroxide into which the carbon dioxide from the combustion of filings of the sample in oxygen has been passed. He stated t h a t the barium hydroxide inay he titrated with acid in the presence of barium carbonate without losing c:irbon dioxide if the acid be run deep into the solution by means of a long c:ipillary t u l x for any dioxide set free is absorbed again by the hydroxide) ~iliovc.. (Cf. J xiid the Bruhns, p. 4 2 6 S u f i e r . ) Roscnthalerand'l'iirk (Arch. f-'hamz.,'244,,;17 former alone (Ib.id., 244, jjj ) investigated the percvntnge of dissolved substarice absorbed from I per cent. solutions oi it in difr'crcnt sol~-ents h y 5 tiriYc.5 its weight of different kinds of charcoal in the enscs of codei!ic.. caffeine, ialicinc, picrotosine, gallotannic, gallic mid oxalic acids. IJO tassium oxalate, indigotine and glucose. The amount aiic! rate of x sorption are greatest in the case of animal charcoal. grcat a l ~ with o '.tlesh"

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REVIEWS.

and less so with “plantblood” charcoals, and are small with “blood,” “limewood” and “sponge” charcoals. They are greatest in aqueous solutions, then in descending order come ethyl alcohol, methyl alcohol, acetic acid, acetone and chloroform. There is relatively less adsorbed in concentrated than in dilute solutions. Adsorption and decolorization are little dependent on the temperature. The more readily a substance is adsorbed the more difficult it is t o dissclve it out again. The decolorizing power of Charcoals is dependent on their adsorbing power. Charcoal t o be used for decolorizing should be carefully purififd and used in as sinal1 amount as possible. Solutions in solvents other than water and as concentrated as possible are advisable. Substances readily oxidizable must not b’e decolorized with animal charcoal. The percentage of a substance adsorbed increases with its molecular weight. Coloring matter in a solution usually has a high molecular weight and its concentration in the solution is usually small, both being conditions favorable t o adsorption. Castellana (Gaz. chim. itul., 36 I , 136, 232) stated that the green flame test for boric acid is obtained if the substance be mixed with potassium ethyl sulphate and heated with the flame till the first vapors rise and then setting fire t o these. 0.5 mg. of boric acid may be detected. The characteristic odors of their esters are obtained with a considerable number of organic acids if carefully heated dry with potassium ethyl sulphate. He stated in reply t o Velardi’s (Zbid.,36 I, 230) criticism t h a t copper chloride, phosphites and hypophosphites do not interfere with the boric acid color and that the turmeric paper test is not superior t o his in delicacy. Fendler (2.Nalar.-Genussm., 11, 137) gave a modification of the turmeric paper test, comparing the color obtained under certain conditions with a variety of standard colors obtained with known amounts of boricacid. Low (THISJ O U R X ~ L2 8, , 807) found that the turmeric test is extraordinarily sharp if the paper be dried not a t ICO’ but a t ordinary temperatures or 40Oto 50’ in a vacuum desiccator. I n I cc. O.OOO,OOI gram of boric acid may easily be detected. In the quantitative determination it is not possible t o drive all of the boric acid out of water solution with methyl alcohol because the smallest amount of water will hold back considerable acid. All the acid may be driven over by the use of some water-extracting substance like calcium chloride. Hinden (2.anal. Chem., 45, 33.2) said that the taking up of silicates, after evaporation with hydrofluoric acid may be accomplished by evaporating 4 t o 6 times with hydrochloric acid, the bases being converted into chlorides. One gram of substance is moistened in platinum with a little water and evaporated down with I O t o 1 5 cc. of concentrated hydrofluoric acid, the residue taken up with hydrochloric acid ( I : I ) , I O cc. of hydrofluoric acid again added, evaporated and the evaporation repeated about 6 times with I O t o 2 0 cc. of hydrochloric acid. Complete decomposition is not t o be obtained in this way with barium and lead-bearing glasses; here the recommendation is made t o filter off the insoluble residue and t o treat again with the two acids. Schucht and Moller (Rer., 39,3693) titrated hydrofluosilicic acid with sodium hydroxide in the presence of methylorange, adding first an excess of .neutral 3CaC1, 6NaOH = 3CaF, calcium chloride solution. H,SiF, 6NaC1 H,SiO, 2H,O.

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abletals, General.-Tarugi and hlarchionneschi (Boll. chim. j u ~ n i . , 45, 629) gave some particulars regarding the use of thioacetic acid rccoiiimended by Schiff and Tarugi (Guz. clzini. ,itul.,24, j 51) in qtnlitativi. analysis. They stated that it works well. Under pressure iii scalcd tubes a t yoo it gives complete p ipitatioii of sulpliidcs much niorc readily than hydrogen sulphide. a in acid concentrations su(:h that under normal circumstances no sulpliides would foriii. 'l'lic zictioii of thioacetic acid in closed L-essels a t ooO is equal t o t1i:tt oi hydrogen sulphide a t 14.34 atmospheres. Daitz (Z.t i i i t r l . (,./zcuL., 45, (12) criticized the animoniuni sulphide group separation of lbetticher (Ibi'd. 43, 99)>saying that in the separation of cobalt, iiickc.1, iron nnd niangi nese from aluminum. zinc and chroniiuni by excess of sotliuiii liydroxide and bromine a good deal of nickel and sonic cobalt go into solution; also t h a t on treatment of the first four as hydroxides iritli concentrated hydrochloric acid, evaporation, addition of excess of miiiioiiia, heating to boiling after strong shaking and addition of 2 t o ;. cc. of li?-tlrogcn peroxide and filtering, much nickel and some cobalt arc left iii tlic rcsi'due while a good deal of iron and iiiangaiiese go into thc filtrate wliich should contain only complex nickel and co1:)alt sdts. Jannascli and Heimann ( J . fir. CIzeiii. [ 2 ] 73, 473, 43s) gave some more metal scpamtions by distillation in a current of dr!, hydrochloric acid gas. Tin distils over away from cadmium a t :t tenipcrature not a b o ~ i .320". His-muth is separated from cadmium by distilling a t tcriiperaturcs between 180' and 3 jo'; bismuth niid silver niay be easily separated. Xntin:on!r distils from lead mixture between I j o o and 250'. Antimony aiid copper, cndrniuni or silver n i a \ - be sep:iratetl. Thc tenipcr;ilure need in no case exceed 3 50". The authors upheld their mcthod against Friedhehi's (Z. a n d . C:heni., 44, 465) criticism. Alkalies.--Hubener (Clzcm.-Ztg., 30, 58) in detecting sodiuni sulphite in thiosulphate made use of thc fact t h a t the sulphur dioxide lihcratetl from the thiosulphatc requires twice as much iodine for its oxidation as does the thiosulphate itself. Na,S,O,. jH2(.I I = fSa?S,O,; Sa1 -+ Sa,SO, A- 6H,O. SO,+ \jH,O. S a , S,O,.jH,O 4 H,SO, = SO, f S 21 H,O = 2HI H,SO,. One determination is niade direct, with iodine, another by passing the sulphur dioxide e\-olved in an atniospherc of carbon dioxide through an excess of iodine and titrating back. l'hescs two values by suitable calculation give the amounts of sulphitt. and thiosulphate in the samplc,. He found in a samplc supposr>dl?-30 p:r cent. pure, 92.87 per cent. thiosulphatc. 3.11 per cent. sulphitc and 2.66 per cent. sulphate, the last figure representing sodiuiii sit1ph:tte corrcsponding t o t h e barium sulphate difference of the totally oxidized saniple and t h a t calculated t o correspond to the sulphite and thiosulphatc. Cormimbocuf (Ann. clziwz. anal. u p p l . , 11, 130) dcterniincd ~)otassiu~ii chloride in potassiuni hroniide by precipitating both :is silver salt a n d weighing. 2 grains of pure potassium bromide should gi1-c 3. I 396 grams of silver bromide while 2 granis of potassium chloride should I V L ~ , ~ I 3.8j23 grams as silver chloride. He assumed I per cent. of ptassiuiii 7 chloride would increase thy weight of the silwr hroinidc 11y c~.ooO~)z gram and gave a table for the chloridr: content of the hroinidc. 1); (Gaz.clzim. ital., 36 11, 150, 298) stated t h a t the solul)ilit!- of pot^ or potassium xnd sodium persulphate is increased by t h e prescncc o i I

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REVIEWS.

sodium sulphate and decreased by potassium sulphate, the solubility coefficients per IOO cc. a t 1 2 O being for saturated solutions of sodium sulphate 5.982, of primary sulphate 8.72, of potassium sulphate 0.792, of primary sulphate 0.329. There is direct proportionality t o the greater or less solubility of the sodium or potassium salt. The solubility of the persulphate in sodium salt solutions is a function of their concentration of sodium. Hence the greater solubility in the presence of sodium salts is probably due t o chemical action. K,S20, Na,SO, = Na,S,O, K,SO,. On this ground he criticized Tarugr's (lbid.,34 I, 324) method for the determination of potassium. Schlicht (Chem.-Ztg., 30, 1299) observed t h a t sodium phosphomolybdate solution gives a yellow precipitate when heated with potassium salts acidified with nitric acid and makes a good test for potassium. Beryllium, ,Vagnesium, Alkaline Earths.-Glassmann (Ber., 39, 3366, 3368) gave a quantitative separation of beryllium and aluminum, neutralizing the hydrochloric or sulphuric acid solution of the oxides approximately with sodium carbonate and adding excess of sodium thiosulphate, then boiling till the odor of sulphur dioxide disappears and heating for hour on the water bath. Beryllium remains in solution as sulphite or basic sulphite. The aluminum hydroxide and sulphur precipitate is washed and ignited. The excess of thiosulphate in the filtrate is decomposed with hydrochloric acid and the beryllium precipitated with ammonia or according t o Glassmann's method with potassium iodide and iodate, which according t o Friedheim (lbid.,39,3868)was first described b y Joy in 1864 and later by Zimmermann in 1887. Parsons and Barnes (THISJOURNAL, 28, I j89)separated beryllium from aluminum and iron by neutralizing the chloride solution as nearly a s possible with ammonia, treating the cold solution with IO grams of primary sodium carbonate, heating the mixture a s rapidly a s possible t o boiling and boiling for I minute. The beaker is set in cold water t o cool, the precipitate filtered and washed with hot water and dissolved on the filter in a s little hydrochloric acid (I:I ) a s possible, diluting t o IOO cc. in the original beaker. This solution is neutralized with ammonia and the precipitation repeated. The filtrate and washings are neutralized with concentrated hydrochloric acid, the precipitate dissolved, the solution boiled t o drive out carbon dioxide and the beryllium precipi-, tated by amnionia a s the hydroxide, this washed with ammonium acet a t e solution, dried, ignited and weighed a s the oxide. The aluminum hydroxide precipitated is dissolved in hydrochloric acid, reprecipitated with ammonia, ignited and weighed. The iron separation is the same. Grimbert ( J . pharm. chim. [6] 23, 237) carried out the Schlagdenhauffen reaction for magnesium by treating IO cc. of the solution with j cc. of I O per cent. potassium iodide and 2 t o 3 drops of a concentrated sodium hypochlorite solution. In the presence of magnesium a reddish precipitate looking like ferric hydroxide is obtained. The test is delicate t o I : 2 0 0 0 ; the solution must never be acid. Bellier (lbid., [6] 23, 378) treated the magnesium solution with a solution of iodine in potassium iodide and then dropwise with dilute sodium hydroxide. With more than 0.02 per cent. of magnesium a relatively abundant reddish brown precipitate is obtained; with 0.005 per cent. a reddish brownyellow color. A delicacy of I : zoooo is claimed for this modification.

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REVIEWS.

Ammonium salts, acids and alkalies prevent the reaction conipletely ; lime lowers its delicacy somewhat. l ' h e precipitate is perhaps a misture of magnesium oxide and iodine. lierju (ciicin. -%is., 30, 8 2 3 ) dcterinined small amounts of magnesium iiidircecly hy weighing the pliosphoric acid of inagncsiuni aiiiii:oiiiuiii ~~1ioq)Iiate 3 s 1 12~)5.2&iIo()3. Lob (Ibid., 30, 1 2 7 5 ) iound that ljariuiii dioside could not !:e titrated with permanganate in the presence of :ulpliuric acid lxcause the bzriurn sulphate apparently occluded coiiic of the :uljst;inc,>, but it might be in the presence of hydrochloric acid and iiiciliga1itse sulphate. 'i'lie results of the method were coiiiijared with t i m e oi 31: iodornetric one, the barium dioxide in hydrochloric acid solution k i n g trcatcd irith potassium iodide solution and the iodine titratcd h c k with tliiosulphnte. A neutral or weekly aiiiiiioiiiacal s,olution of t h e ~ l k a h i ccart11 ~ was treated by Benedict (THISJOUKS.\I., 2 8 , is$!) \villi its \-olumc: of 5 times normal hydrochloric acid, then 2 to .; cc. of s:ituratcd 1:otassiurii iodate solution. KO precipitate iiidicatcs t h e a h e l i c e of l x r i ~ i ~ i ;in i, inii~ediate one shows considerable and ;L slow (iiic littlc hriiiiii or considerable strontium. The filtrate is tested iritli ;i little i::o~c than an equal volume of saturated ainmoniuni sulphate solution alid licatetl to tioiling; a white pernianent precipitatv indicate:; strontiuii;. A h o t h e r portion of the original solution is alloncd t o itand Ivith twice it:; ~01uii:e of saturated potassium iodate solution for 1 to I : i h u t c d t c r sliaking, then the filtrate is tested with i its voluiiie of :IIiilliOliiL1lil oxalate for calcium. Caron and Raquct (13~11.S N . c/i;7)?. [; ] 35, 100 I ) precipitntc (1 bzriuni as clironiate froiii tlic :iIlxliiic eart 11 i:iixture, then after n:;ilciiig t h e filtrate alkaline again witli aniii;onia threw out tlic ht roiitiui>i with alcohol. The calcium x i s tcstcd for with Ixktssiuni f(,i-roc!.::rijtlc, SIlution. Iron. Aluminum.-Komar ((,'/zeiii.-Zf,g., 30, 1 5 , ; r j ol)taiiiecI tlic salt I:eH (SO,),.~H,O by evaporation of a solution of ierric s u l ~ ~ l ~~~pi rt eepared Iiy the oxidation of n solution oi ferrous sulphate in sulpliuric acid by incans of nitric acid or by electro!ysis) from a sulpliiirjc acid coiitclit of 400 CC. of the monohydrate per liter t o a concentration of 45' to ,joo Bauiiii.. The compound is pnrtl>-easily solutile iii w t c r . rt1y tlilficultly. The a t first cloudy and finally clear green solution react 5 wcal~lyacid , and does not reduce pernianganatc. H y heating ;it 90' to I ooc 111c conipound destroys paper and sinells of sulpliuric acid; o i i g:cntl!- licating in :i crucible sulphur trioside and ferric oside are o!)t:iinc-tl. 11-011 and zinc may be separated by conversion into su1ph:ites. dissolving tlicse in sulphuric acid (400 cc. of iiionohydratc per liter [cl. I * > to 1-41). ci.aporating this solutioii to dryness and igniting thc. rckluc t o coilstant Twiglit over the burner. The zinc sulphxte ~1ecoiii11osc.s oiil!- a t a h o u t 7 o o o and may be extracted with w-atrr. Rupp :ind IIorii (:1~ch. I j h o m . , 244, 571) modified Rupp's (Uri.., 3 6 , 164) nictlrod i u r t h e titration of ferrous salts with alkali hypoioditc, using caustic 1'otai.li i i i p1:ice of ' 0 dium potassium tartrate as t h e hydriodic acid 1)iiicliiig ajiriit. 1;errous iron is instantly oxidized t o ferric b!- tlic 111easur~dt'sc mal iodine in the presence of norninl or 5 r c r cctit. c:iustic 1:otach. 'l'lie solution is then acidified with acetic or Iwttc~rwith oxalic acid m d tlic iodine excess titrated with thiosulp1i:itc. Moody (Am. J . S c i . [4] 2 2 , 483; Z . umrg. Chew., 5 2 , 2 S 6 ) gave a n

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iodometric determination of basic alumina and free sulphuric acid in aluminum sulphate and alums. The iron is determined in aliquot portions before and after reduction witl- zinc, and any zinc by electrolysis from acetate solution. A portion is boiled with potassium iodide-iodate mixture in a suitable apparatus and the iodine collected in a receiver containing potassium iodide. After slightly acidifying with sulphuric acid the iodine is titrated with thiosulphate. The precipitate formed in the flask contains besides alumina,ferric and zinc oxides which are determined in the usual ways. I molecule of alumina requires 6 atoms of iodine, I of ferric oxide 6 of iodine, I of ferrous oxide 2 of iodine, 5 of zinc oxide 8 of iodine, I of ammonium I of iodine and I of sulphuric acid 2 of iodine. The decomposition of zinc sulphate is abnormal. IgZnSO, 20KI 4KIO, 12H20 = gZn,(OH),SO, 12K2S04 241. The total iodine less the sum calculated t o correspond to the single sulphates gives the iodine difference; if this be positive the,mixture contains free acid, if negative, free alumina. c’obalt, iVickel, iVanganese, Zinc.-Alvarez (Ann. chim. anal. apple, 11, 445; Cheni. News, 94? 306) stated that the blue color pointed out by Donath in 1901 as obtained when solid caustic potash or soda or very concentrated alkali solution was added to cobalt solutions is obtained also when barium hydroxide, calcium chloride or other water-extracting substance is added. I drop of I : IOO cobalt solution added to boiling concentrated alkali solution will give the reaction, which takes place in the presence of nickel. Grossmann and Schiick (Ber., 39, 3356) gave a new test for nickel, treating a solution of dicyanodiamine with a httle hydrochloric acid, heating t o boiling, adding the nickel salt, then caustic potash solution and obtaining a yellow crystalline precipitate of nickel dicyanodiamidine (Ni[C,H,ON,E.aH,O) in needles arranged in star shapes. They are immediately soluble in potassium cyanide, but not in boiling caustic potash solution, and are sparingly soluble in water and ammonia. Cobalt forms no analogous compound. Reichard (Chem.Ztg., 30, j56) stated t h a t if powdered dehydrated nickel salts of mineral acids are heated with an equal amount of fully dry methylamine hydrochloride in porcelain the color becomes deep dark blue. This color disappears on cooling, leaving a dirty gray-yellow,solid mass which soon deliquesces. It becomes blue again on heating and decolorizes on cooling. The color is shown with 0.1 mg. of nickel. Cobalt salts similarly heated yield deep blue oily drops which do not lose their color on cooling. Funk (2. anal. Chenz., 45, 562) observed t h a t iron and manganese sulphides dissolve very easily in dilute acids, but in the presence of ammonium salts nickel sulphide and even more easily cobalt sulphide dissolve, too. Lit ordinary temperature nickel and cobalt sulphides are not dissolved by a little dissociated acid like formic but in separations they dissolve and some iron sulphide remains. Manganese sulphide dissolves except for traces. Jannasch and Gottschalk (J. fir. Chem. [ 2 ] 73, 497) precipitated manganese from ammoniacal solutions by means of oxygen rich in ozone. Small amounts of manganese can be precipitated by slow passage of the ozone through the ammoniacal solution. Large amounts are managed by adding the manganese solution dropwise to IOO cc. of strong ammonia through which a vigorous ozone current is

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REVIE\YS.

passing. The precipitate is hydrated niaiiganesc dioxide. Nanganese may be separated from sodium, calcium and zinc in this nianncr by one precipitation. hIagnesiurn, nickel, cadniiuin and coppcr each rc-quirc. a repetition of the precipitation in ordcr t1i:it the n:aiigaii free from them; the precipitate is disaolvctl in h!-drochloric a ing hydrogen peroxide. The separation oi niaiigmese and cobalt failed. Tarugi (Gaz. clzim. ital., 36 I , 332) gave :i test for iiiangnn method for the formation of glycerosc. 1Ir;iigaii in glycerol and such a solution colors itself red h y oxidation through air or more quickly through oxygen or sodiuni liypochloritc. 'l'lie color intensity depends only on thc amount of 1i1:i:igancsc' 1)rcsciit. O.OOOOI gram of manganese can be detected. Cobalt and copper interfere only with amounts of less than I per 1000. Gl!~erol is coiivcr:.ecl iiiio glyeerose through sodium hypochlorite ijy I drop oi I : i(ic10 cobalt chloride solution. j o cc. of glycerol, 2 cc. of 5.9: IOGO cobalt chloride and I O cc. of 5 0 per cent. caustic soda put all a t once into 150 cc. of sodium hypochlorite (7 per cent. active chlorine) ga\-c on cooling in ice, 1 8 pcr cent. of glycerose. Bertrand and Javillier (Contpt. wizd., 143, 900; Uzdl. soc. clziiii. 14 J I , 63) gave a method for the precipitation of zinc, t r containing zinc and a sufficient amount of lime with e and heating t o boiling, the calcium zincate coming o crystals. I t is difficultly soluble in excess of limp and may 11c used for quantitative work. The zincate is niised with carbonate ; thc preeip itate is dissolved in hydrochloric acid, the Lolution evaporated t o drj.ness, the residue taken up with some water, the lime precipitated u i t h ammonium oxalate and the filtrate e\-aporated :inti ignited with sulphuric acid to zinc sulphate. Less than I part of zinc in ~joo,Oooof solution can be detected. A zinc test was gi\-cti also h!- 1:radlc.y (uec. undcr copper). .VEKUYY, Silver.-Rupp ( B e y . , 39, 3 7 0 2 ) gave a volumetric clcteririination of mercury, adding t o the niercuric salt solution (about 0 . 2 gram in 2 5 to 50 cc.) I t o 2 grams potassiuiii iodide so that thc precipitate first formed dissolves, making alkaline with caustic potasli or hoda, then adding with shaking, a mixture of 2 t o 3 cc. of 40 pcr cent. forn;aldeh\-de and I O cc. of water. The mixture is acidified with acetic acid t o distinct odor, an excess of tenth-normal iodine solution (25 cc.) itcldc.cl~the metallic mercury brought into solution by shaking and thc. excess of iodine titrated with tenth-normal thiosulphate. U t z ( / > / [ o m ! .Pmt, 39, 785) modified his 1905 method of determining suhliinatc in drcssing iriaterials t o conform to this mercury determination of Iiupp's. Seidc.11 ('1'11is JOURNAL, 28, 73) determined mercury and iodinc in :uitiseptic soaps by treating the soap sample with I j o cc. of 9j per cent. alroliol arid 3 to j cc. of concentrated hydrochloric acid, warming thc n!isiurc and adding gradually small amounts of water till the whole is in solution. Mercury is precipitated as sulphide, filtered into a Gooch crucible : ~ n d washed with 95 per cent. alcohol. The filtrate freed iroiii f:it ilia? be shaken in a separatory funnel with chloroforrri and a few drops of nitrous acid and the iodine in the chloroforni deterniined hy titration wit.11 thiosulphate. Goldschmidt (2.WZO/. C h i n . , 45, 8 7 ) stated t h a t silver is precipitated quantitatively as a black powdcr, if cobalt foil \)e p u t into

REVIEWS.

445

boiling silver salt solutions and t h a t i t may be weighed. Gold is likewise thrown out of boiling solutions by nickel as a brown powder. Copper, Cadmium, Bismuth.-Bradley (Am. J . Sci. [4] 22, 326) observed t h a t the blue color of “logwood hematoxylin” and copper salts is a copper test of extraordinary delicacy, I : ~ooo,ooo,ooo. Zinc nitroprusside is crystalline and may be detected under the microscope even in the presence of amorphous precipitates, the reaction being much more delicate than the common precipitation tests for zinc. Rhead (Proc. Chem. SOC.,22, 244; J . Chem. SOC.,89, 1491) determined copper with the aid of standard titanium trichloride solution in the presence of potassium thiocyanate. Cupric salts are reduced and the copper precipitated in the presence of sulphuric or hydrochloric acid as cuprous thiocyanate. A ferrous salt is added to sharpen the end-point. The cupric salt oxidizes a n equivalent amount of the ferrous salt and the red color of ferric thiocyanate appears. The color disappears a t the end of the reaction. The titration must be carried out below 30’ and as rapidly as possible. Nitric acid must be absent. Ferric iron and cupric copper may be determined together and the iron subtracted after separate determinations. The titanium trichloride is standardized by means of a ferric salt solution obtained by the oxidation of a ferrous salt with permanganate. Goldschmidt (2. anal. Chem., 45, 344) observed that cadmium is quantitatively precipitated from boiling salt solutions in aluminum dishes in the presence of traces of chromium and cobalt nitrates. The catalyzing agent is aluminum. Other metals can be used for the quantitative determination by catalysis. Moser ( I b d . , 45, 14) found t h a t bismuth precipitated as phosphate would carry down some cadmium in the separation of bismuth from copper and much cadmium and that the cadmium is hard to remove. It is not easy to make a second precipitation of the bismuth phosphate because of its insolubility. The method is good for the determination of bismuth alone but as a separation has no advantages over the ordinary one. Uranium, Vanadium, Molybdenum, Tungsten.-Finn (THISJOURNAL, 28, 1443) separated uranium and vanadium, after solution of the mineral sample in sulphuric acid, b y precipitating twice with excess of sodium hydroxide solution, boiling each time, acidifying the united filtrate and washwaters with sulphuric acid, adding ammonium phosphate and making alkaline with ammonia. The filtrate containing vanadium is acidified with sulphuric acid, reduced with sulphur dioxide till the solution is blue and titrated hot with permanganate. The uranium precipitate (UO,NH,PO,) is dissolved in sulphuric acid redhced with zinc and the filtrate titrated with twentieth-normal permanganate a t 60’. The iron factor multiplied by 1.631 gives vanadium pentoxide, by 0.9159 vanadium, by 2.567 uranous uranic oxide and by 2.133 uranium. Gilbert (2. ofientl. Chem., 12, 263) determined molybdenum in glance b y extracting the trioxide with ammonia, after roasting in air, and igniting to constant weight. The small amout of molybdenum left in the roasted ore is obtained by fusing with potassium and sodium carbonates, taking up with acid, reducing with zinc and titrating with permanganate. Von Knorre (Stahtl u. Eisen, 26, 1489) modified his earlier method for determining tungsten in steel. The steel is dissolved in hydrochloric

446

REVIEWS.

acid with exclusion of air and without filtering the acid is neutralized with sodium carbonate; after cooling, I O cc. of approximately tenthnormal sulpliuric acid or alkali sulphate and 40 to 60 cc. of benzidine solution are added. 'l'lic precipitate of tungsten, beiizidine tungstate and sulplintc is filtered, w:tslied with dilute benzidine solution and ignited in platinum. 'l'lic iroii bearing tungsten trioxide is takcii up by fusion with sodium c,~rboiiati..t!ic iiiclt extractcd -;yitIi 1101ivxtcr, the iron oxide filtered o u t . t n ~ 1 tile solutiori acidified with h!-clrochloric acid (using nietliyl orange). After addition oi I O cc. of sulpliuric acid the tungsten trioxide is precipitated xvitli beiizidinc solution, filtered, washed as before, ignitecl antl weighed G S trioxide. 1i:iZtts (1Uc.vtcuz C'hemis,f t:iinedby tlic nietliod of lr.:~st sciwres. z 1 . 7 0 .L --- (.).oz~;xJ' -t(i.0138 .x' O . U O I I ,Py O.OOO- J9s .zf. 'I'lie gold content c x r i also be obtained from graphic reprcscntatioii. 'i'he palladium determination is simpler, the. conductivity is oiily insignificantly dfectcd by tlie free acid content and is iicarlj, proportiorial n-itliin certain limits to the pallndium content. The iiumb2r of mg. oi'p.illudium per ~ o cc. o is given by multiplying I . ? I 'Y i o r - 4 b y the iiicrexc iii conducti~ity. 'I'hc mean error here is 0 . 3 pclr cent. .\laxson ( A m .J . .\'cy. [4] 21, 27.1; %. ( ~ m ~ rChciu., ~q. 49, 1 7 2 ) made satisfactory colorimetric dcterminxtions of gold in small amounts, preparing liis red colloidal solution by inixiiig gold chloride antl saturated aqueous acetylene solutions. Uic content of such solutions was deterniiiicti g~tvimi.trically 3 x 1 dirfereiit concentr;1tions i r e r e preparcd by exact tliliitiori. First a (hllcnkampf then ;t I'enficld colorimeter was used. 't'lic least determiiiuble yu:tntity \vas o.ooo,o I gram ; t,he largest aniomi t \vas o.ooo8 with an error of o.ooo,oG. Petersen ( Z . a i d . Chevz., 45, 342) instead of the usual separation ol gold, platinum, mtiniony and uscnic in the li)-drogen sclphide group, prccipitatetl all tile metals of the group and soiii(> cobalt and nickel from ivcakly acid solution with zinc turniiigs. After \vxrniing for ': hour tlie precipitatc as xashcd a n d warmed wit11 rlilutc. !iydrochloric acid; cadmium, tin and some cobalt dissolved. 'l'iit, i.csitluc I Y ; I ~ washed then boiled with dilute nitric -7:

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447

acid; mercury, lead, bismuth, copper, nickel dissolved leaving gold, p!atinum, antimony and some antimonic acid. This residue was ignited with I t o 2 parts of ammonium nitrate and 5 parts of ammonium chloride in porcelain ; antimony volatilized as chloride. The residual gold and platinum were dissolved in aqua regia, and detected through concentrated ammonium chloride or sulphur dioxide or alkaline hydrogen peroxide, Arsenic, antimonyand zinc must be tested for in special portions. The original solution was tested for zinc by precipitating with sodium carbonate, dissolving the precipitate in hydrochloric acid, passing in hydrogen sulphide and decomposing with excess of sodium acetate ; white zinc sulphide was precipitated. Orloff (Chew.-Zlg., 30, 714) observed that hydrogen peroxide seems to dissolve osmium and osmium hydroxide to a marked degree to osmium tetroxide. Histological specimens blackened by osmic acid are completely decolorized by hydrogen peroxide. From mixtures of the platinum metals obtained by reduction with zinc or magnesium the peroxide dissolves only osmium. Silver iodide rapidly blackens with palladium chloride or bromide, forming a mixture of palladium iodide and silver chloride. Soluble alkali and alkaline earth iodides form insoluble precipitates with salts of other platinum metals, hence a potassium iodide solution may he used only with certain precautions to separate palladium from the others. But freshly precipitated silver iodide changes only palladium chloride to black iodide. Thompson and Miller (THISJOCRNAL, 28, I I 15) determined melting points, cooling curves, microstructure, densities and electrical conductivities of platinum silver alloys containing about I O , 2 0 , 30, 40, and 50 per cent. platinum, They concluded that i t is not possible t o separate platinum from gold, iridium, etc., b y alloying with silver and dissolving in nitric acid, that platinum alloys of more than 20 per cent. platinum cannot be completely separated by concentrated sulphuric acid, and t h a t the irregular results obtained from treating these alloys with nitric acid are caused apparently by the existence of platinum silver compounds. They analyzed the alloys by treating them hot with concentrated solphuric acid in two portions. diluting, filtering and washing out the silver, then igniting the residue in porcelain. This residue was taken u p in aqua regia and evaporated nearly to dryness with nitric acid. The solution was diluted and the silver precipitated with sodium chloride solution. The precipitate was washed free from chlorine, dissolved in ammonia and reprecipitated with nitric acid. From the solution in sulphuric acid the silver was precipitated after dilution either as sulphide or as chloride. Reichard (Pharm. Centrh., 47, 391) gave a new reaction for tin, treating a little finely pulverized uric acid with some drops of stannic chloride solution, then adding concentrated sodium hydroxide to the mass dropwise with stirring till nearly all is dissolved and heating. A gray to intense black fleck is formed. Stannous compounds do not give the reaction, neither do arsenic or antimonic acid. Lead and cadmium do not give it. Copper hydroxide gives a black on heating without the uric acid, owing t o the formation of copper oxide. Mercuric chloride gives a reddish brown compound. Bismuth gives the same reaction as tin but the precipitate is insoluble in sodium hydroxide. 0.0001 gram of tin may be detected. Nitric and hydrochloric acids destroy

448

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the black residue only slowl?- and incompletely, sulphuric acid iiiiincdiately. d.lzsci~ilu~zi~~ic.c.-liiniiiii (Aiti ricctd. LI'IICL'L 15,11, 3 2 0 ) stated t h a t both Iiicgler and Eblcr ha\c overlooked his work 011 hydrazine ~ o l u metric iiietliods. I IC) niodifiecl liis iodonietric method by carrying out the determination in alkaline solntiori , thus a\.oiding tlir: separation of iodin(,. ,;X214,.H2SOl.- ?I\i!darc tliroJ\.ii tiway. [he following 20 cc. must cotitairi tlic methyl alcohol antl arc t v s t c d for it. Aldehydes with plicnol cliaracter give a siriiilar violet color which is, howevcr, quite stable toward reducing agents ; the formaltlcliydc color is not. Gascard (./. filiui.iii. c h i / i i . [6] 24, 97;. c!etcrniint.d [lie iiiolecular weight of alcoliols arid phenols 11>- heating tl dried sul, st:incL, in :t long-iiec1;i.d fhsk \\-it11 2 t o 3 times tlie tlic,ore. ,c':il amount of hviizoic acid anhydritle for 24 Iiours ir! :i \r:itei or oil ha, !I, the flask being covered. 111 iiiost cases 1)oiliiig c:ilciuni cliloride solution (cold saturatcd) will do for the h i t l i . 1c) to 20 c'c. of ether are mii into tlic flask, tlieri 5 cc. of \\-atcar :ind 2 drops of phenolphthalcin and the liquid titrated with normal pot:tsli. hIolecular wviglit P = p -t 1000 ,' (S--n), wlierc p = wiglit of sulxt;iiice, S nuiiiber of cc. of caustic potash I I = iiuiiihctr of cc. of c'instic potash found i i i the blank detcrniination .thing but thi. alcohol or plleiiol. In the case of a polyalcohol tlii, result is to be irinltiplied by tlie number of alcohol groups present. \Vhere tlic bvnzoic acid ester is difficultly soluble in ether, hcnzciii. or chloroform are u s d . 1iOH 1.(C,j€13C02')20 = C,H,.COOR + C,H,.COOI-I. I lie f r w benzoic acid is titrated. Iclason and Carlsori ( B e y . , 39, 73s) tleteriiiined organic hylrosulphidcs m t l thioucitls by titration with iodine and with alkalies. 211SI-1 -- I, - - R,S? ? H I . Only thiocyai~ic acid is iridiffereiit to iodiiica. Aroniatic liycirosulphides arc strong enough acids to give neutriil salts with alkalies in :ilcoholic solution and a s ; I I-csult they can be titrated \\.it11 :ilkali aiitl Plic,nolplitlialeiii ill alcoliol solution. With the aliphatic liytirosulpl~idcs the indication is not siiarp antl with tliioglycolic acid it hils, v v v i i in alcoliolic solutioii. Rowritiialvr (.4vch. PIz(zm~.,244, 3 7 3 ) ~iseilSessler's reagent a s :I test for hydroxyl groups a n d ioL111d that. c-scept Ixnzliydrol. octJ.1 anti cetyl ;ilcohols, :ill coinpounds that 11c tricd coiit:tining primary antl swondary alcoholic Iiyilroxyl groups. o i i boiliiig for I minute g;ivv rcduction. 'l'hesc three did oii hoiliiig for sonic hours witli a return condenser. Co~npouiids xitli tc,rtiar!, xlcoholic Iiydrosyl do not reduce Sessler's rcagent. Of coliipounds with phenol e!iar~icter---p~iciiol, salicylic acid. guaiacol, tliymol, resorciiiol, phloroglucinol, and orcinol $\-e no reduction. sylcnols antl creosol i i i i unimportant, li!.droci"iiionc., pyrocatechol iiritl gallic acid ;in eiiergrtic rcrliiction. 'l'he Sacchse liquid retluces, but not t h y K i i ~ ~ psoliition. p Nvssler's rwgcnt m a y hi. used to test airiylcm. 11~dr:itt~ for ferincating amyl alcohols :ind citric acid for tartaric. ~

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451

Carobbio (Boll. chzm farm., 45, 365) tested for resorcinol by letting to 2 cc. of the suspected ether flow down the wall of the test tube onto cc. of zinc chloride with enough ammonia to give a clear solution. IYitli 0.01 to 0.001 gram of resorcinol the place of contact turns yellow, then green and after a few minutes blue. 'Traces require considerably longer. Alcoholic hydrochloric acid added carefully forms a weakly rsd layer between the ring and the ether, spreading through the latter on shaking. By this reaction, 0.01part of resorcinol per 1000 can be recognized in a few minutes Hydroquinone gives the yellow ring. changing soon to a brown-red. Pyrocatechol and adrenaline give a garnetred ring. De? -3.lii.re (]. filzainz. chznt. [6] 23, 244, 281, 332) determined glyco, finding the amount of glucose pre-existing in the ornd that formed b y hydrolysis. Two portions of the gan in qur me of I O , the other of 40 grams. The IO gram portio11 organ are is digectea w .I j gram of pepsin in the presence of water and a little sulphuric acid l,r 6 hours a t 48' t o 50'. A little more sulphuric acid is addtd and the whole heated to I I j o - 1 2 0 ' in an autoclave for I 5 hours. The cooled contents of the autoclave are heated with slight excess of mercuric nitrate, then dilute caustic soda added to neutral or weakly alkalini reaction, the whole diluted and filtered. IOO cc. of the filtrate are sha'en with 4 or 5 grams of zinc dust to separate the mercury, filtered, cc. of this treated with caustic soda till the zinc precipitatcd dissolvc gain, water added to 55 cc. and the glucose determined gravimetrically or b y titration. I n the calculation the volume of the precipitate obtained in the purification should he subtracted from the volume of the liquid, here zoo cc. The glucose pre-existing in the solution is determined in the 40 gram portion by extracting with water, the united extracts are purified with mercuric nitrate and caustic soda, the volume brought t o 1000 cc., the filtrate treated with zinc dust and the determination carried out as above. Ottolenghi (Attz. uccad. Ltncez, [j] 15 I, 44) stated that the reaction of Neuberg and Rauchwerger for the detection of cholesterol (with rhamnose and concentrated sulphuric acid) is not characteristic of cholesterol but is given by phytosterol from many sources. Neuberg (2. phystol. Cltem., 47, 335) admitted this t o be true. Windaus (Clzenz.-Ztg., 30, IOI I) detected small amounts of cholesterol in the presence of phytosterol by the difficult solubility of cholesterol dibromide in a mixture of ether and acetic acid. IOO cc. of a 50 per cent. mixture dissolves only 0.6 gram, 40 cc. ether and 60 cc. acid only 0.25 gram of cholesterol dibromide. Addition of a little water lowers the solubility while much water causes the phytosterol dibroniide to separate out in an oily form and to crystallize with more difficulty. Cholesterol dibromide may be obtained almost quantitatively by dissolving cholesterol in a little ether and adding a solution of bromine in acetic acid (5 grams in IOO cc.). The use of petroleum ether gives a cholesterol salt of different melting point. Aldehydes, Ketones.--hIeth (Chew.-Ztg., 30, 666) stated that one of Rimini's (Ann. furnzucol., 98, 97) tests for formaldehyde, that of the red color with ferric chloride, phenylhydrazine hydrochloride and hydrochloric or sulphuric acid, occurs also with acrolein even though with different shade and less delicacy. Rimini's other test with phenylhydrazine hydrochloride, sodium nitroprusside and sodium hydroxide givI I

453

REVIEWS.

grams of freshly ignited carbon, when the odor of benzoic acid is evident. The cooled test treated with a drop of I per cent. ferric chloride gives a reddish brown precipitate in the presence of benzoic acid. A violet color changing to blood-red on shaking shows salicylic and a brown color, green on shaking, tannic acid. I n the latter case the tannic acid is precipitated as iron tannate and salicylic acid detected in the filtrate by the violet color. The iron tannate is dissolved in hydrochloric acid, diluted and shaken with ether. On slow evaporation of the ether, crystals of benzoic acid appear and may be identified by the aniline blue reaction. Herzog (Festsciirtjt A d o l ) Lieben, 440; .4nn. 351, 263) gave a test for lactic I, = acid, treating the silver salt with iodine. 2R.CIIOH.COOAg R.CHOH.COOH RCHO 4 CO, zAgI. The acetaldehyde may be detected with sodium nitroprusside and piperidine. Amino acids were carefully converted in the cold into the a-oxyacids by means of silver nitrite and their silver salts treated a s above with iodine. Glycocoll, alanine and other higher homologues can thus be detected. Schloss (Beilr. clzem. Physiol. u. Patliol., 8, 445) detected glyoxylic acid by means of indole and skatole. With no ring formed a t contact zone between solution and skatole (0.2 gram in IOO cc.) there is no glyoxylic acid present. If a red or brown ring is formed, the following test should be tried. 20 cc. of liquid are decolorized with animal charcoal, I or 2 cc. of dilute sulphuric acid added t o a portion of the colorless filtrate and let stand for I O minutes in a waterbath a t 50'. The skatolereaction should be set u p in another portion, adding about I cc. of skatole solution and pouring concentrated sulphuric acid down to the bottom. The first portion is tested with indole. A sharp red ring after a t most 2 or 3 minutes points to the presence of glyoxylic acid. The skatole reaction alone is not positive. Glyoxylic acid to O.OOO,OI grani can be thus detected in wine. Sullivan and Crampton (Am. Cltenz. J . , 36, 419) detected tartaric acid or tartrates by means of the crystalline structure of the calcium salt. j o cc. of the.concentrated salt solution containing not more than 30 per cent. of dry substance are rendered alkaline with caustic potash, a few drops of 2 0 per cent. potassium acetate added, acetic acid t o acidification and then IO cc. of 30 t o 40 per cent. calcium chlori-le solution. The mixture is stirred for I t o 2 rniniites and allowed to stand for 1 2 to 15 holm a t room temperature. Thc calcium tartrate crystallizes in rhombic prisms or pyramids recognizable under the microscope. KO other organic acid gives a calcium salt of similar form. Citric and oxalic acid precipitate, malic dcw not, but in the presence of these acids the calcium tartratt. is thro n oiit in needles and plztes. Tocher (Pharm. ,I. [4] 23, 87) used a couple of reactions for the detection of citric, tartaric and malic acids. Tartaric on heating with concentrated sulphuric acid gives a black mass, citric a yellow solution and malic a dark solution. Tartaric gives with cobalt nitrate a red solution becoming colorless with excess of caustic soda, deep blue on boiling, the color fading out on cooling. Citric gives a deep blue solution, and a precipitate if the neutral solution be boiled with calcium chloride solution. Malic gives also a blue solution but no precipitate with calcium chloride and gives on heating with dilute sulphuric acid and potassium bichromate the odor of ripe fruit. Ulpiani and Parrozzani (Atti accad. Lincei, [ j ] 15 IT, 517) gave a rapid determination of citric acid in lemon juices, determining

+

+

+

454

REVIEWS.

first the approximate total acidity of the juice with iiornial sodium 11ydroxide, then putting j o cc. in a zoo cc. flask with enough normal so dium hydroxide to neutralize about 1 / 1 0 of the total acidity. This value represents the maxiniuiii proportion of tartaric anti oxalic acids which are then precipitated after thc acldition of about 17 grams of calcium cliloride aiid ,i grains of aniinal charcoal a n d boiling. 'Clie Inisture is cooled, made up to volume aiid liltcred. The following detcrminations are made in t!ie iiltratc.: ( I ) 50 cc. arc titrcitecl with normal sodium hydroxide till n h i n t permanent turbidity appears. nnrl ( 2 ) a i l other 50 cc. arc boiled ant1 titrated wit11 the caiistic soclit to turbidit!.. The difference in sodium hydroxide betwc.cn ( I ) and ( 2 ) represents 2 / 3 of the frec and coinbind citric :wid in tlic ,j:iicc. Iiastle (Pziblz'c Health and iWnvinc- Hospiinl .Serricc 1:. . \ . fijyicvzic Lnb. Bull.? 50. 26, 31) stated t h a t small amounts of s:tcccliariii iieatcd n-itli sin:ill :i:nounts of n rc' agent (,j cc. of plieiiol :znd :, cc.. 01 co~1cciitmtc.dsulphuric acid) for 5 niin utes a t 160' to I;o'. thc. iii;iss tlissolvecl in ;z little j\-ater and inade allaline with twicc normal caustic sod^, gives a purple or dcep rcd color :Lccording to the ;tmoLtiit of s:iccl~triii. '!'lie liniit is o.oz5 mg. Salicylic and b-nzoic acids do not iiitirfcre, neither do cumarin or etliJ.1 fi-sulphobcnzoatc. I'anilliii bccomcs yellow, tlien ret1 iii the cold ; heateti to IGO' to 1 7 0 ' it is first hlooc!-i-ctl. thcn almost b1:ick: nftcr thc addi. tion of cawtic soda it is dccp tlai-k rccl. \\;ith other plienols substitiiterl for ordinarv phc~nolin t1w t v s t t l w follo~riiigcolors :ire obtained : Phenol Pyrocatechol Hydroquinone Resorcinol Tricresol Phloroglucinol Thymol

Saccharin at I G n O to I Green Dark red-brown with blue fluorescence Salmon color with strong greenyellow fluorescence Purple-red Wine-red Clear blue

Vanillin at ioo0 Dark blue to green Dark red-brown Red with weak green fluorescence Deep purple-red Ye1lo \v Clear red

Cumarin a t 100' gives colorless (Tvitli tricresol) to orange-yellow (with phloroglucinol) compounds. Stanek (%. physioi. C l m z . , 47, 83, : Z . Zzcckerind. BBhmen, 31, 316) found t h a t choline precipitates from a c d or alkaline solutions with potassium triiodide while betaine precipitates only from acid. To 2 j cc. of a t most a \j pcxr cent. solution of thc mixture of both hydrochlorides ,j per cent. primary potassium or sodiuill carbonate is added and precipitation made with the triiodide : t h e choline periodidc is filtered, washed and the nitrogen determined. 'I'll? filtrate is concentrated to about 2 j cc., then about I O per cent. sulphuric, acid added, the liquid saturxted with sodiuni chloride, and potassium triiodide :iddec-l as long as a precipitate forms. This is filtered. washed with saturntcd sodium chloride solution and the nitrogen determined. The action of other nitrogen bases with potassium triiodide is tabulated and the method applied to the clctcrmination of choline and betaine in vegetable substances. Derivatives n ) Cai,bo.nic and Uvic Acids, Heteyocyclic Conzpomds.-4ckermann (2.phyc.iol. Cizent., 47, ,766) recommended benzene sulpho-

.;ne

REVIEW s.

495

guanidine as a means of detecting guanidine in the presence of arginine. 3 grams of guanidine carbonate warmed in 30 cc. of water are shaken with 6 cc. of 33 per cent. caustic soda and 4 cc. of benzene sulpho-chloride when, on cooling, white crystals of benzcne sulphoguanidine separate out. They may be recrystallized frotn boiling water and boiling alcohol, and melt a t 212'. In IOO cc. of water 0 . 0 2 gram is soluble. Arginine does not give the corresponding compound. Cumming and Masson (Chem. News, 93, s, 1 7 . From Proc. SOC.Chem. I n d . Vierona, 1903. July-August) gave a new method for the determination of cyanates in the presence of carbonates. KCNO zHC1 H,O = KC1 "$1 CO,. The titration is first made in the cold for carbonates, with congo red or methyl orange a s indicator, then an excess of acid is added, the solution boiled and the acid excess titrated back. -4 second determination of the cyanic acid may be made by boiling the solution containing the above reaction products with excess of caustic potash and determining by titration the amount of the latter required to break up the ammonium chloride. Herter and Foster ( J . Biol. Chem., I , 2 j 7 ; 2 , 267) gave an indole determination, treating a dilute solution ( I : IOO,OOO of water) made weakly alkaline with caustic potash with a drop of z per cent. ,&naphthoquinone sodium monosulphonate, yielding a blue or blue-green color. With more indole, well formed crystals of a bluish color are obtained. The greencolor fails a t a dilution of I : 1,024,000. The compound is soluble in chloroform with red color and this solution may be used for colorimetric work. Skatole is separated from indole by distillation and determined by a colorimetric method which rests on the blue color caused by Ehrlich's reagent. Konto (2. physiol. Cheni., 47, 185) detected indole in putrid albumen by distilling off 1 / 3 of an alcoholic solution, making the distillate alkaline with caustic soda and distilling, making this distillate acid with sulphuric and distilling. To I cc. of this are added 3 drops of 4 per cent. formaldehyde and an equal volume of concentrated sulphuric acid allowed to flow onto it. With a trace of indole the whole solution becomes a magnificent violet-red. The reaction is visible with I part of indole in 700,ooo of water, but not in 800,000. Ronchese ( J . +harm. chim. [ 6 ] 23, 3 3 6 ) determined uric acid with titrated iodine, IOO cc. of urine being treated with I j cc. of ammonia and I j grams of ammonium chloride, the precipitate filtered and washed with a solution of I j o cc. of ammonia and 150 grams of ammonium chloride per liter, brought into solution in 300 cc. of water with some acetic acid, 2 0 cc. of saturated borax and primary potassium carbonate solution are added and the solution titrated. The number of grams of uric acid in I liter of urine is equal to the number of cc. of tenthnormal iodine multiplied by 0.084 plus 0.01. I molecule of uric acid requires 2 atoms of iodine. Sperling (2.Oestevr. Apoth. Ver., 44, SI) treated 2 to 3 cc. of a I : IOO aqueous solution of phenyldimethylpyrazolone with 2 drops of fuming nitric acid and after the appearance of the green color, added carefully 5 cc. of concentrated sulphuric acid. A cherry-red ring was obtained a t the contact zone, which spread through the whole liquid on shaking. The reaction is characteristic for antipyrine and its derivatives except amidopyrine. Other substances treated as above gave the following results:

+

+

+

+

4.56

Salicylic acid. . . . . . . . . . . I : ,joo Quinine sulphate. . . . . . . I : xoo " hydrochloride . . I : zoo Cocaine " . . . 1:xoo Codeine " . . . . I: IO0 Phenol. . . . . . . . . . . . . . . . I : 100 Resorcinol. . . . . . . . . . . . . . I : xoo Antipyrine salicylate. . . . I : 3 0 0 Nigranine.. . . . . . . . . . . . . I : xoo Tussol. I : IO0 Pyramidone.. . . . . . . . . . . I : I O U

ICEVIEWS ed.

.\ddition of s u l p h u r i c acid gave.

. . . . . . . . . . .........

gold-yellow color '. "

............

I'

/
1. 6 j,OOO Hydrastine and canadine. . I : 30,000 I : 2000 Strychnine. . . . . . . . . . . . . . I : 200,ooo I : 40,000 Iirucine., . . . . . . . . . . . . . . . I : 40,000 I : 10,000 Quinine. . . . . . . . . . . . . . I : 100,000 I : 20,000 Cinchonine.. . . . . . . . . . . . . . I : 90,000 I : 10,000 Coniine.. . . . . . . . . . . . . . . . I : 130o belowI: 1000

1V.

I : 38,000 : 220,ooo

: 80,000 I : 2400 1 : 43,000

I : 41,000

I : 11,000

I : 500,000

I

I

: 10,000

I : 2 j,OOO

I : IOO,OOO

I : 12,000

I

I : 1300

belox71 :

1000

'I'he a l l d o i d s were detected and localized in sections of a number oi plants. Coniine gives no precipitate in aqueous solutioii. 'The sectiou treated x i t h barium mercuric iotlitlc solution is washed quickly with water mid laid in a o. j per cent. solution of potassium bichromate in 30 per cent. chloral hydrate and acidified with f e n drops of hydrochloric acid A yellow t o ~-elloiv-hronnsolution indicates the alkaloid. Joncscu (Re?-. ~ > i z a r i i i . (;LY,, 16, I 30) obscr\wl t h a t by 'l'honis's niethod of prccipitatiori wit11 potassium bismuth iodide and decomposition of the prfcipitate x i t h alkali not only atropine and hydroscyainine but quinine, cai'fcirie and antipyrine may be nearly quantitativ-ely precipitated. From I gmiii of quinine uscc! tlie :iutlior obtaincd 0.9405 gram, of caffeiiii. 0.9546 and of antipyrine 0.g27,; gram. AIoiiti (Gc.J7im. ;fa[.,36 11, 477) criticized the reaction of ,Il\-arez for aconitine and gal-e one of his own. Tlic alkaloid (o.ooo2 to o.001 groiii) was treated in porcelain with 2 to 4 drops of siilpliuric acid ((1. 1.75 to 1.76)lieatcd for 5 or G niiiiutcs on :t boiling n-ater bath, tlicn a sniall amount of resorcinol added and tlic \vholc \-;arincd further. is. yellow-red color appears, attaining cl niasiiiitiiii after - 7 0 iiiinittes. 'L'lius o . o o o ~gram can be detectLd. Reich:ird ( C h c w - Z i q . , 30, io9 on picrotosinc: 1'11(17~1. Zfg., 51, rGS, 591 on cocninc, 5 3 2 on cluinoidinc, S i ; 011 opiritii alkaloids; Pha7,771. Ccizirii., 47, 247 on inorpliinc, 347 011 cocaine, 473 on berberine, 623 on thebaine, 7 2 7 on codcini., ro.S, 1048 on narceine) has again publislicd a series ot' articles oti a1k:iloitls. Colo~in!7 .71~1h.i~'t7l.s,( )I'ls.-Green, Yeoman arid Jones (Mon. ~ c i . 141 2 0 I , 131) gal-c ;t nicthod for the systematic analysis of colors on animal fibers. The method inclutlcs two operations; in the first the color is remo\-ed from the fiber and its chemical behavior studied, in the sccond it is reduced a n d t h c coiirsc of its rcoxidation studied. Given tlw coloring matter alone i t is reduced with zinc dust and oxidized witli air and with chromium trioxide; if on the fiber i t is reduced with hydro sulphite and oxidized with air arid potassium persulphate. Their classification foilom : I . Lkcolorizcd by hydrosulphite and regenerated in air : azines, oxaziixs. thiazines, indigo. 11. Dccolorized h>- li!di-o sulphite, not regenerated in air but by chromium trioxidc : triphenyl methane colors. J I I . Destroyed bj' hydrosulphite : nitroso a n d nitroazo colors. I17. S o t changed by hydrosiilphite : pyrorics, acridines, quinoleins, thiazoles, certain antliracene colors. Y. Changed to brow1 products by hydrosulphite anti rcLgcncraied in air or by potassium pcrsulphate : most :iri'iliracc,ne colors. Knowing tlic class, chemical reactions and shade tliv choicc is limited to a fern closelv allied colors. Graefe

461

REVIEWS.

(Chem.-Ztg., 30, 298, 299) gave the following main differences between lignite pitch and other pitches. Melting point.

Lignite pitch.. . . . . . . . . . . . . . . . . 86‘ Coal tar pitch.. . . . . . . . . . . . . . . . . 91-92’ Wool fat pitch.. . . . . . . . . . . . . . . . 32’ Stearin pitch. . . . . . . . . . . . . . . . . . 43O Petroleum pitch I... . . . . . . . . . . . 33O Petroleum pitch 11... . . . . . . . . . . 73O Petroleum pitch 111... . . . . . . . . .126O Lignite “goudron” . . . . . . . . . . . . . . 52 O Wood pitch.. . . . . . . . . . . . . . . . . ,195’

Residue after extraction with benzene. Sulphur.

46.0

2.14 0.31

0.0

0.00

0.0 2 .o

0.67 1.17

0.0

3.5

I .09

4.0

I

0.0

1.88

42 .o

.oo

0.00

Iodine value.

93.7 50.0

36.9 40.4 49.4 70.3 103.5 66.5 140.~

A test for phenols which serves to distinguish lignite pitch from other pitches is given. A little of the asphalt is pulverized and boiled with some normal caustic soda and filtered. A little of a solution of a few drops of aniline in I cc. of hydrochloric acid and I O of water with some sodium nitrite solution added in the cold is added to this alkaline liquid. A red or reddish brown color or precipitate appears according to the phenol content. Without phenols the liquid is only yellow. Valenta ([bid., 30, 266) used methyl sulphate in the detection and determination of tar oils. It dissolves the hydrocarbons of the benzene series or mixes with them in all proportions while hydrocarbons with open carbon chain and petroleum distillates do not dissolve in the cold and even esters are difficultly soluble. A measuredamount of the oil sample is poured into a IOO cc. glass stoppered measuring cylinder and 1.5 to 2 times as much methyl sulphate added. The whole is shaken and the volume of the lower liquid after separation read, the difference giving the amount of oil dissolved. The tar oils may be precipitated from solution by caustic potash. A gravimetric determination is possible if the caustic soda be neutralized, the whole shaken with alcohol and the oil weighed after driving off the latter. Rebs (Protokoll I. Stzg. Komm. Bekampj. Missverstand., Herst, etc., Farben u. Alalmaterialien Niirnberg, 1906, 35) determined turpentine resins or abietic acid in resins of various sorts, oil and copal lacs, pitch and paper by treating IO grams of substance with 2 0 to 2 j cc. of I O per cent. alcoholic potash, warming, deconiposing the soap, after cooling, with dilute hydrochloric acid and filtering, washing and drying the separated resin. The pulverized resin is extracted with 50 cc. of warm petroleum ether, the abietic acid precipitated from the filtered solution as ammonium salt, separated and the ammonia driven off hy gentle heat. The remaining resin-like mass gives the resin content of the substance. For less accurate work the substance may be extracted with benzene and the saponification omitted. Vaubel (2. Bfjentl. Chem., 12, 107) simplified his last year’s method for determining turpentine oil in the commercial product by adding to I to 2 grams of oil in chloroform roo cc. of water, 5 grams of potassium bromide and I O cc. of concentrated hydrochloric acid or a corresponding amount of sulphuric acid and then titrated potassium bromate solution till a permanent bromine color appeared. Genuine oils of turpentine have a bromine absorption of 2 2 0 to 230 while t h a t of substitutes falls a s low as 16 sometimes. Paulmyer ( L a Savonnerie Marseillaise, 6 , No. 62;

462

REVIEWS.

SeiJensZederztg. 33, 286) made use of the "critical solution temperature" of various f a t t y oils for detecting adulterations in cocoanut oil. A cloudy mixture of f a t t y acids warmed with acetic acid will clear u p suddenly and the temperature a t which it does so is constant for each acid (critical solution temperaturc). M'ith pure cocoanut oil fatty acid, the liquid clears a t 3;'. Warmcd a little above this and allowed t o cool with stirring i t will cloud a t 33'. 'rhe value for various acids is: Cocoanut oil.. . . . . 33' Rape oil.. . . . 107' "Palnikerniil". . 4 9 O Earthnut oil . . . . . Sesame oil.. . . . . . . Niger oil.. . . . . . . . Castor oil. . . . . . . .

Linseed oil . . :z0 Stearic a c i d . , . 94O (commercial) Olive oil.. . . . . 93' Oleic a c i d . . . . . . 9s' .' 8j o Cotton oil. . . . . 8 2 . 5 ' 13. j o"hkifentalg" . . SS'

90'

Ygo

With mixtures of the f a t t y acids the difference in solubility temperatures is proportional to the quantities of single acids present. Twitchell (THISJOURNAL, 28, 196) found that a fat with excess of water and less than I per cent. of naphtlialenestearosulphonic acid will be almost completely saponified in 8 to I O hours. This acid tried on a soluble glyceride, triacetin, showed about the same hydrolyzing power as hydrochloric acid, but the latter has practically no action on an insoluble glyceride like a common fat while the organic acid works almost as well as on a soluble ester. The capacity of these sulpho fatty acids t o dissolve a s well in fatty acids as in water and t o make fatty acids soluble is of value in the separation of solid and liquid fatty acids. B u f f e r , LVlilk.-Robin (Comfit. rend., 143, 512) detected cocoa fat and margarine in butter by means of the facts that the fatty acids of cocoa fat are nearly completely soluble in 56.5 per cent. alcohol a t 15' while those of butter arc only partly and those of margarine difficultly soluble; and t h a t the content of water-soluble fat in butter is much larger than i n the others. The butter sample is heated with alcoholic caustic potash and the liquid so diluted with water after cooling that a j 6 . j per cent. alcohol results. X blank determination with the same amount of alcoholic caustic potash is carried out, and both are titrated with half-normal hydrochloric acid in j 6 . 5 per cent. alcohol. The difference gives the amount of acid needed for the separation of the fatty acids in the first flask and the soap there is cleconiposed with this amount of acid, the liquid diluted to 1 5 0 cc. with 56.5 per cent. alcohol, cooled t o r g O and filkred. In j o cc. of the filtrate is found by titration with tentlinormal caustic potash the amout of fatty acids soluble in j 6 . j per cent. alcohol. Another ,jo cc. arc cvaporatcd to 15 cc., the water-insoluble fatty acids filtered out, dissolved in a mixture of alcohol and ether, titrated, thus giving the amount of fatty acids soluble in j6.5 per cent. alcohol but insoluble in water. 'l'liv difference between these two values givcs water-soluble acids. Butter

Acids soluble in alcoliol. . . . . . . . . . . . . . . . . . . . insoluble in water. . . . . . . . . . . . " soluble '' " . . . . . . . . . . . . . . . . . . . Water insoluble: water soluble. . . . . . . . "

II

.67-14,83

i.SI-

8,31

lfargarine.

Cocoa f a t .

2.6j

46.69 44.71

i..j(~ 0.11

231.7

I

.9s

225.9

Alcock (Pha~w. ,I. [4] 23, 28) detected formaldehyde in milk by adding to 3 cc. the snnie volurnc of 2 0 per cent. caustic potash, shaking hard, lien adding a n excess of strong hydrochloric acid and warming carefully.

REVIEWS.

463

A coagulum is obtained, colored more or less deep violet according to the amount of formaldehyde, while the liquid below remains colorless. Bonnema (Pharm. WeeKBlad, 43, 434) found t h a t the mean freezing point of milk is - 0 .j j j ’ and t h a t i t is influencd by dissolved crystallizable substances. The amount of water added can be determined by means of 555x88 5-88 j the change in freezing point. D = 0.555 x88.5 o r w = 0L-_--I * , w “I- 88.5 D where w is the weight of water added in grams and D is the freezing point in degrees below zero. This formula applies to milk with an average of 88.5 per cent. water. The freezing point rises a few hours after milking because of the formation of ammonia by bacteria and by which some phosphates are precipitated. The subsequent lowering is due to the formation of lactic acid which dissolves some of the precipitated phosphates. Comanducci (Rend. accad. scienze fisiche e matem. Nufioli, 1906, April) observed t h a t a certain amount of pure milk requires always the same amount of potassium permanganate to oxidize the organic matter in it. Watering can be detected in this way. I cc. of cow’s milk requires j o to 52 cc. of tenth-normal permanganate, goat’s milk 44 to 46, sheep’s 43 to 48, ass’s j 5 to 58, woman’s 53 to 60, these oxidation indices sinking if the milk is adulterated. Cow’s milk with IO per cent. of water requires 44 cc. permanganate for I cc., 2 0 per cent. 39. With half the cream removed the oxidation index fell also to 44 to 46. Cow’s milk with an oxidation index of less than 50 is therefore suspicious. Lelli (Arch. farmncol., 5 , 645) detected primary sodium carbonate in milk by means of aspirin. Milk, an equal volume of water and a little aspirin are heated to 60’’ the opaque solution filtered, and the filtrate treated with a little IO per cent. ferric chloride solution. In presence of the carbonate an abundant red-yellow precipitate is formed. 0.5 per cent. of carbonate can be detected. Trillat and Sauton (Compt. rend., 142, 794; 143, 6 ; Bull. SOC. chzm. [3] 35, 906, 1207) gave a determination of the albuminous substances of milk and the casein of cheese, making use of the property of formaldehyde of rendering these albuminoids insoluble without changing their weight. j cc. of milk are diluted with 2 0 cc. of water, the liquid boiled 5 minutes, j drops of commercial formaldehyde added, the liquid boiled for 2 or 3 minutes longer, allowed to stand for j minutes, treated with j cc. of I per cent. acetic acid, shaken and the pulverulent precipitate collected on a tared filter. The precipitate is washed with water, extracted with acetone, dried a t 70’ to 80’ and weighed. The casein determination is similar. Blood, Glucosides.-Carlson (2. plzysiol. Chem., 48, 69) stated t h a t 3 per cent. hydrogen peroxide is to be preferred to ozone in turpentine oil for the guaiac blood test, as i t gives a sharper and more certain reaction. Schumm (Ibid., 50, 374) disagreed with this. Horoskiewicz and Marx (Berl. Klin. Wochsclzr., 43, 1156) observed that IO to 15 per cent. quinine solution is a good extracting agent for old blood flecks, giving a brown yellow solution with a characteristic absorption band between C and D (wave lengths 628 and 596) instead of the ori@nal OXYhemoglobin bands. Eight per cent. quinine solution mixed with the blood in ratio 2 : 4, heated slowly and gradually to boiling and treated after cooling with 2 to 3 drops of fresh ammonium sulphide solution will &e with normal blood a dirty brown-green, but if the blood contain carbon

464

REVIEWS.

monoxide it stays carmine-red. Seisser aiicl Sitchs ( I b i d . , 42, 44; 43, 3 ) detected human blood by the iise of specisc scra. If huniaii serum be tnised 1vit.h an antiserum obtained tJy i . ~ c : t t i x t ~of rabbits with humaii serum a mixture is obtained mliicii is c:!p:tble O i ii:ter:+etioii. If 23 serun1 r iii - ~ heinolysin be addcd. i t :iii.is '111:1 in i :)I; 1.~ .1ii.1 in; i ii a11t i :I pc ' s sera c ~ L I S Ccessation of Iicniol i n t;:is C:LSI.:, ,111 ctli i I; L e s! !o \YI i ti1ciii selves inactive. Blood spot iiiontlis old on liii ga1-c the rcaction. Rabbit serum ( 0 . 2 5 cc.) is placed in tile liqud to bc tested Cor human blood and mixed with the antiserum ( p r e p a r d froni rabbits trcateti previously with human serum), t!:c niisture allovictl to stand for i hour at j;', then I cc. of 5 per cent. sheep blood emulsion added and let stand again a t 3;' n-ill give proor of tlic pr IIW of human blood, if hemolysis fails t o appear. I t is PrrI-eiitL'd hy the interference of o.0001 cc. of human seriim and even o.ooo,ooi a n d u.o~~o,o(ioi cc. ciiii 1)e detected by distinct differences in the heinol>-tie :ictioii. ' i ' l ~;nethod is a t least as delicate as the cktectioii I>!- pccipit~itioi?. I'iorkoivski (13cr. fiIzarm. Gcs., 16, 2 2 6 ) observed tl12it ti;(? i~ydrocclcliqtiic! gi\.es coagulation with human but not Jvith coic's milk. !t.sitL AIIi.~-c,tl /Vc~uves.-Leconite ( j . fihn?,ii2. c h i i l l . [6] 24, 4?7) gave a method which makes it possible t o distinguish and to count with a magnifying glass the threads of different libels in niixed weaves. I t consists in diazotizing the silk and wool which coiitnin eacli an amino group antl to couple on a phenol group iii :ilkaliiie solution. Wool coritains also sulphur and so by siniultancous action of an alkaline p l u n bite solution, lead sulphide is formed, concealin,p the azo color. I’1ai:t fibers contain ncithcr of these substaiiccs and remain uncliaiiged. Oiic clecimeter of decolorized weitve is put into 30 cc. of I O per cent. nitric acid 30 cc. of 5 per cent. aqueous nitrite solution added during 3 minutes gradually and wit11 stirring, allowed to stand 10 niinutes, washed for 2 minutes with water. pressed out a n d cut into 2 pieces. Over oiic is poured 40 cc. of ,S-nnphthol pluinbite solution (50 grams of caustic sotla in 500 cc. of u-atcr, 2 - grams of lead acetate in 300 cc. of iwter sloir-I:,. :dtlcd and 5 grams of P-naphtliol addccl to the clear liquid) ; the other piece is trwtetl with 40 cc. of x s o r cinol-pluinbitc solution ( 2 grams of resorcinol i:i p h c c of t!ic naphthol). ’r‘he xve2ves a r e nnslied aftcr I hoiir a t riot :3boT:;, ?om\;.it11 r:inning watcr for I