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of the product. T h a t hydrogenation takes place by degre’e according t o t h e unsaturation of t h e f a t t y acids, will not always be anticipated. It will be, therefore, unsafe t o attach too much importance t o the inner iodine value oi a hardened oil without taking into account the iodine value of the oil itself. For hardened chrysalis oil of a n iodine - \ d u e above jo, an inner iodine value exceeding I O O may probably be expected. V-
S U &I MAR Y
The results of t h e present investigations may be summarized as follows: I-The hydrogenated product of the unsaturated f a t t y acids of chrysalis oil consists mainly of stearic acid. 11-Besides palmitic acid. some higher saturated acid or acids are present in chrysalis oil. This substance is probably an eutectic mixture of stearic and palmitic acids. 111-By t h e Kreis and R o t h method, no saturated acid higher t h a n stearic was found in t h e hardened chrysalis oil. IV-An inner iodine value exceeding IOO may probably be expected in t h e case of a hardened chrysalis oil having t h e iodine value above 50. INDUSTRIAL EXPERIYEXT STATION
TOKYO, JAPAX
THE USE OF DIPHENYL GLYOXIME A S AN INDICATOR IN THE VOLUMETRIC DETERMINATION OF NICKEL BY FREVERT’S METHOD R p G. I,. KELLEYA N D J. B. CONANT Received December 2, 1915
A volumetric method for determining nickel in iron and steel as devised b y H. L. Frevert was published in Blair’s “Chemical Analysis of Iron,” 7th edition, 1912. Since t h a t time the method has been constantly in use in this laboratory, b u t inasmuch as some small changes have been made from time t o time i t seems best t o republish t h e method with these modifications. Accordingly me give below Frevert’s method as originally proposed. except for t h e modifications mentioned above, and follow it with a discussion of t h e use of diphenyl glyoxime as an indicator. FREVERT’S METHOD F O R THE DETERMINATIOK
OF NICKEL
I N STEEL
( A ) SOLUTION O F T H E sAI\IPLE-For ordinary nickel steels, a I-g. sample is taken, b u t mith less t h a n 0.10or more t h a n j per cent of nickel,larger orsmaller samples may be taken. I n t h e absence of more t h a n small amounts of chromium, solution is most rapid in j o cc. of hot dilute nitric acid (sp. gr. I . I ~ ) b, u t with chromium present in amounts greater t h a n 0 . 5 per cent, or under circumstances where chromium carbides are present, more satisfactory results are obtained b y dissolving t h e sample in 60 cc. of dilute hydrochloric acid ( I : I ) with t h e aid of heat. When solution is complete, t h e iron and t h e carbides are oxidized b y adding nitric acid, drop b y drop, until effervescence ceases. Boiling removes the products resulting from t h e decomposition of the nitric acid after which t h e solution is cooled. T h e quantities
VO~. 8, NO. 9
of acid given here are those which are convenient €or use with samples of I g. or less. ( B ) P R E C I P I T A T I O N O F K I C K E L D I X E T H Y L GLYOXIXE--
T h e solution obtained, as described above, is rapidly cooled b y the addition of a lump of ice, after which are added in succession: 1 2 g. of citric acid or equivalent solution, 20 cc. ammonia water (sp. gr. o . 9 0 ) , sufficient solution of dimethyl glyoxime t o precipitate all nickel present and enough more ammonia t o make the solution distinctly ammoniacal. The mixture is thoroughly stirred after each of these additions. The solution of dimethyl glyoxime is prepared b y dissolving 2 0 g. of the reagent in 1300 cc. of ammonia water (sp. gr. 0 . 9 0 ) , after which enough water is added t o bring the volume u p t o 2000 cc. Ten cc. of this solution allow sufficient excess t o completely precipitate 1 . 5 per cent of nickel in a I-g. sample, i. e., about 0.01 j o g. of nickel. (C) T R E A T X E N T O F K I C K E L D I M E T H Y L G L Y O X I b I E PRECIPITATE--When the amount of nickel is small (0.10 per cent or less), time must be allowed for complete precipitation- an hour is usually ample. With amounts larger t h a n this, no danger of lorn results attends immediate filtration. For this purpose an asbestos mat on a z-in. perforated porcelain plate or a Buchner funnel may be used. The solution containing the suspended precipitate will usually have a volume of zoo t o 2jo cc. It should be stirred thoroughly and poured on t o the asbestos mat in such a way t h a t the funnel always remains partly filled with liquid. Strong suction should be avoided. Quantities of precipitate corresponding t o less t h a n j per cent of nickel in a 1-g. sample rarely cause trouble in filtering. b u t the difficulty rapidly increases with larger amounts. When all of t h e precipitate has been transferred t o t h e asbestos, i t is thoroughly washed with water. Both wash water and filtrate are discarded, although t h e latter may be tested with dimethyl glyoxime if i t is believed that all of t h e nickel may not have been precipitated. (D)
SOLUTIOK
AND DECOhIPOSITIOK
O F THE PRECIPI-
TATE-The receiving flask and tip of t h e funnel are next well rinsed with water. With the mat still in place, b u t with suction off, enough nitric acid is added t o cover the asbestos t o a depth of in. After a minute, suction is applied, t h e acid drawn through t h e filter and about as much more added, taking care t o c o \ w the entire surface. At this po:nt there should remain no visible trace of the red precipitate. The mat is now t o be thoroughly washed with water, t h e washings being collected in t h e flask with the acid. The solution so obtained is then transferred t o a 400 cc. beaker in which it is heated t o boiling. Here the solution is ailotved t o cool slightly t o facilitate t h e addition of I g. of either potassium chlorate or ammonium persulfate. The solution is boiled until clear; this usually involves a considerable reduction in bulk, often as much as jo per cent, Insufficient boiling may cause trouble ( I ) through failure t o decompose t h e dimethyl glyoxime, which would reprecipitate when t h e s olution is subsequently made ammoniacal, or ( 2 ) because if t h e solution is not freed from oxidizing products
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T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
of t h e chlorate or persulfate decomposition t h e indicator which is used t o determine t h e presence of a n excess of ammonia may be destroyed. -4 cheaper a n d somewhat simpler device for dissolving and decomposing t h e dimethyl prec pitate consists in treating it with 50 cc. of a mixture made u p of 4 0 cc. of hydrochloric acid and I O cc. of nitric acid. This acid filtrate and t h e wash waters when evaporated t o a bulk of 50 cc. will be found t o be free from dimethyl glyoxime and ready for t h e next step, t h e neutralization with ammonia. ( E ) T H E K E U T R A L I Z A T I O K O F T H E ACID N I C K E L SOLUT I O ~~ I T HA n r M o N I A - T h e cooling of the acid solution
may be hastened b y adding ice. Neutralization need not be made with great care, b u t i t is well not t o have t h e excess of ammonia indefinitely large: j cc. of strong ammonia water in excess of t h a t necessary t o neutralize 300 cc. of solution causes no harm, b u t quantities larger t h a n this interfere. Out of several indicators tried, rosolic acid showed more stability in this solution t h a n any other. Strong ammonia is usually added rapidly in excess. Dilute nitric acid and dilute ammonia are then used t o complete neutralization, leaving a slight excess of ammonia. T h e red color of the indicator seems t o have a beneficial effect upon t h e subsequent titration of t h e nickel. The volume should be 2 jo CC. ( F ) T I T R A T I O N O F T H E A U M O N I A C A L N I C K E L SOLGTIOK-
Titration is made with potassium cyanide, using silver iodide as indicator. In this connection solutions containing 8.0 g. potassium iodide, 0.j g. silver nitrate, and 4.6 g. potassium cyanide per liter are used. T h e strength of t h e potassium cyanide solution is so adjusted t h a t I cc. of t h e solution is equal t o 0.0010 g. of nickel. This is accomplished b y comparison with a nickel solution of known nickel content, or with a standard steel. T o make t h e titration, exactly I O cc. each of t h e potassium iodide and silver nitrate solutions are added (with stirring), followed b y t h e potassium cyanide. T h e first additions of potassium cyanide increase t h e turbidity of the solution, and u p t o this point t h e addition of t h e cyanide may be rapid. From then on, it is added in rapid drops (with stirring) until t h e turbidity is about t h e same as before adding a n y cyanide. T h e last I j t o 20 drops are added slowly, the end-point being taken as t h e disappearance of t h e ast trace of turbidity. T h e cyanide added of course titrates t h e silver iodide as well as t h e nickel, and t h e result therefore must be corrected b y t h e subtraction of a blank. T o determine t h e blank, add I O cc. each of t h e potassium iodide and silver nitrate solutions t o a nickel solution which has been titrated and which has t h e volume a t which titrations are usually made, and titrate with K C N . By repeating this several times with t h e same solution a n average blank will be obtained which may be regularly used where these conditions apply. I n this laboratory t h e blank has been found as 1.00 cc. of potassium cyanide solution, a n d this blank is accordingly subtracted from all titrations before calculating t h e result. The formula for calculating percentage of nickel in t h e sample is
80j
Number of cc. of K C S - blank = per cent of nickel. Number of grams in sample X I O (G)
SOME D E T E R N I N A T I O K S O F N I C K E L I K
STEEL-
Sample A is a sample of steel prepared as a private standard which has been analyzedin this laboratory b y a number of methods and found t o have 3.03 per cent nickel. This sample is analyzed b y this method twice daily as a check on t h e determination. The last fifty determinations made average 3.03 (06) with t h e highest value 3.08 and t h e lowest 3.01. Samples 3 2 and 33 are samples prepared a t t h e Bureau of Standards. Our analyses with the official figures are given below: Bureau of Standards Sample No. NAME 32 Chrome Nickel Steel 33 Nickel Steel
OFFICIAL VALUE 1 . 6 2 % Ni 3.33CjoNi
THE USE O F DIPHENYL GLYOXIME'
PER CENT NI FOUND Four determinations 1 . 6 3 1 , 6 4 1.62 1.64 3 . 3 4 3.32 3 34 3.32
AS A N INDICATOR
I n outline, t h e method consists in adding a measured excess amount of standard potassium cyanide solution t o an ammoniacal solution of t h e nickel salt. A quantity of t h e indicator is t h e n added and the excess of potassium cyanide titrated with standard nickel sulfate solution. I n t h e early work on t h e method, t h e more widely used dimethyl glyoxime was employed as a n indicator. This was suggested by Lundell2 in an article in which he uses this method in t h e analysis of cyanide solutions. Our experience with this reagent demonstrated t h a t it was unsuited t o use as a n indicator in t h e determination of nickel because t h e results were found t o vary with t h e concentration of t h e indicator in the solution and with t h e excess of cyanide used. Theoretically diphenyl glyoxime is open t o t h e same objections as the above reagent except in one respect, aiz., t h a t owing t o t h e lower solubility of its nickel complex it is not necessary t o use the indicator in as high concentrations as was found t o be necessary with dimethyl glyoxime A solution of t h e diphenyl glyoxime was obtained b y dissolving I g. in a solution of j g. S a O H in I O O cc. of water. This was diluted t o 1000 cc. Wetting t h e diphenyl glyoxime with alcohol before treating i t with t h e sodium hydroxide often helps in obtaining more rapid solution. A solution of nickel sulfate was prepared which contained about 0.001g. of nickel per cc. This was a convenient strength, for in working with a I g. sample of steel 0.1cc. corresponded t o 0.01 per cent of nickel. I t was standardized b y titration against potassium cyanide solution of known strength, using silver iodide as indicator. The titration b y t h e method described here was made b y making t h e nickel solution alkaline with ammonia, adding a measured excess of potassium cyanide solution, followed b y a quantity of t h e indicator, and titrating with standard nickel sulfate solution. All titrations were carried on in a volume of z j o cc., and with every change in t h e amount of indicator solution used a new blank was determined, using the same volume of water and j cc. of ammonia (sp. gr. 0.90). FACTORS U X F A V O R A B L E T O T H E METHOD-Early in 1 This reagent was recommended as a quantitative precipitant for Ni by Atack, J . Chem. SOC.,103, 1317. 2 Trans. A m . Eleclrochem. SOC.,26 (1914), 369.
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the work on this method it was noted t h a t it is unfavorably affected b y ( I ) the presence of salts of strong acids or bases in more t h a n small amounts ( 2 t o 4 per cent), ( 2 ) b y st.rong bases, (3) b y weak bases t o a less extent, and, of course, (4) by acids. Salts such as t h e chlorides, nitrates and sulfates of sodium, potassium or ammonium, in quantities of more t h a n 4 per cent in t h e solution to be titrated, caused precipitation of the indicator and prevented its reaction with t h e nickel salt when this mas present in excess. Strong alkalies, such as sodium hydroxide. in amounts greater t h a n traces, entirely prevented t h e reaction between the nickel salt and t h e indicator. Quantities of ammonia corresponding t o a concentration greater t h a n t w o parts of strong ammonia in I O O parts of solution, made t h e end-point unsatisfactory. The fact t h a t t h e titration depended upon the formation of the double cyanide of course made the absence of free acid necessary. THE C O N C E K T R A T I O S O F T H E INDICATOR-In the results showing the variation in values obtained upon t h e nickel sulfate solution itself with a constant concentration of ammonia and differing concentration of indicator and nickel, t h e cyanide solution was of such strength t h a t each cc. was equivalent t o 0.001g. of nickel; t h e nickel sulfate solutions contained 0.00106 g. of nickel per cc.; all titrations were made a t room temperature in a volume of 2 5 0 cc. T h e results clearly indicated t h a t I cc. of the indicator was too little t o use. As we increased t h e concentrations of t h e indicator a point was reached where t h e end-point tended t o appear too soon b y larger and larger amounts. Titrating in a volume of 2 j o cc. with nickel solution of t h e concentration used here, 5 cc. of t h e indicator solution appeared t o us t o be t h e best amount. It is probable, however, t h a t in titrating in smaller volume or with more concentrated nickel solution, it would be desirable t o use less indicator; and on t h e other hand a larger amount of indicator would probably prove convenient if t h e titration were carried on in larger volume, or if a more dilute nickel solution were employed. The conditions which determine the amount of indicator and t h e concentration of nickel solution are t h a t t h e amount of indicator shall be such as t o give a definite color indication, yet avoid such concentrations in either nickel solution or indicator as will cause t h e precipitation of t h e nickel diphenyl glyoxime complex as a consequence of t h e momentary appearance of a local excess of nickel during t h e titration. T H E C O K C E K T R A T I O N O F amIosrA-Belou~ are given results showing t h e effect of moderately high concentrations of ammonia upon the titration. I n these experiments t h e indicated quantities of ammonia (sp. gr. 0.90) were added t o I O cc. portions of a solution of nickel salt which had previously been made barely alkaline with ammonia. The volume at titration was 2 5 0 cc., containing 5 cc. of indicator, 1 1 cc. of K C N solution and 0.106 g. nickel. Ammonia u s e d . . , , . . 5 c c . Nickel found ( 8 . ) . . , , 0.0107
5 cc. 0.0108
10 cc. 0,0092
10 cc. 0,0104
15 cc. 0.0100
15 cc. 0.0089
It is evident from these results t h a t there is a maxi-
Vol. 8 , No. 9
m u m above which the concentration of ammonia should not go. A large number of determinations not shown here lead t h e authors t o believe t h a t equally good results may be obtained from a n y concentration f r o m t h e minimum necessary t o maintain t h e alkalinity of t h e solution during t h e addition of t h e nickel solu-. tion, u p t o j cc. of ammonium hydroxide (sp. gr. 0.90) in 2 5 0 cc. of solution. This wide margin makes neutralization comparatively easy, for in working with dilute ammonia several cc. in excess may be added without h a r m and the sense of smell is a sufficiently good indicator. THE
PREPARATION
OF
THE
KICKEL
S0LUTIO.K
FOR
TITRATIOS-The nickel in t h e samples is separated from the iron and other constituents of the steel as described above under Frevert’s method, Sections A, B and C. T h e solution of the precipitate is different from t h a t given under Section D, however, with t h e object of avoiding a high concentration of salts in t h e resulting solution. Concentrated hydrochloric acid containing I O per cent nitric acid is poured over t h e precipitate t o dissolve it. Solution proceeds less rapidly t h a n when nitric acid is used, b u t if the suction is not strong, no difficulty will be encountered in dissolving t h e precipitate in about j o cc. of acid. Care must be taken t h a t every visible trace of t h e red precipitate has disappeared before proceeding t o t h e next step which consists in washing t h e asbestos with about 100 cc. of water. The total filtrate, having a volume of I j o cc.; is now evaporated t o small bulk. T h e combination of nitric acid and hydrochloric acid serves t o oxidize t h e dimethyl glyoxime which would otherwise precipitate as t h e nickel complex upon subsequent addition of ammonia. The evaporation is carried almost t o dryness in order t o keep t h e concentration of ammonium salt, which will be formed when ammonia is added, down t o t h e lowest possible value. If some separation of salt has occurred, a drop of either nitric or hydrochloric acid may be added: along with water enough t o t a k e it up. T h e volume of t h e solution is raised t o I j o t o 2 0 0 cc. by t h e addition of water and about j cc. of dilute hydroxide solution ( I t o 3) added. (If this amount of ammonia water is not enough t o render t h e solution alkaline, evaporation has not been carried far enough and trouble may be met later through precipitation of the indicator.) The solution is now ready t o titrate and accordingly standard potassium cyanide solution is added with stirring until t h e opalescence (or bluish tinge) disappears, after which a further quantity of about I j cc. is added. The next addition is of j cc. of the indicator solution which is followed b y titration with standard nickel solution. T H E A i i A L Y S I S O F SAMPLES O F STEEL-In Table I are given results obtained in the analysis of steels with and n-ithout added nickel solution. TABLEI-.kNALYSIS Gram Nickel Sample Added A. ..................... None A . , , . , , , , , , , , , , , , , , , , , 0.0053 A...................... 0.0106 A , , , , , , . . . . . . . . . . . . . . . 0,0212 B. of S. No. 3 2 . . , . , , . , . , , None B. of S. h-0. 3 3 . . . . . . . . . . . None
OF STEELS
Per cent Ni Found Duplicates 3.03 3.03 3.58 3.57 4.08 4.07 5.18 5.18 1.63 1.64 3.30 3.31
Per cent Ni Theoretical 3.03 3.56 4.09 5.15 1.62
3.33
Sept., 1916
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY SUMMARY
I-In t h e foregoing paper, Frevert’s excellent method for t h e determination of nickel has been restated in amplified form a n d methods for avoiding all of t h e ordinary difficulties have been indicated. 11-A new indicator has been suggested for use i n t h e titration which may find favor with some who prefer t h e appearance of a color as an end-point t o t h e disappearance of a n opalescence. 111-Both methods are more accurate t h a n a n y volumetric method for determining nickel in steel which does not involve t h e separation of t h e iron, a n d more rapid a n d less laborious t h a n those which do. By Frevert’s method a single determination of t h e nickel in a sample of steel m a y be made i n 2 5 min. even i n t h e presence of chromium. A trained operator can make j o or more determinations in a day of 8 hrs. T h e method employing diphenyl glyoxime as indicator requires 35 t o 4 0 min. IV-While t h e methods are perhaps slightly less accurate t h a n t h e method which involves weighing t h e precipitate of Xi-dimethyl glyoxime, t h e greater .speed which is possible i n routine determinations more t h a n compensates for so small a loss in accuracy. RESEARCH DEPARTMENT, MIDVALE STEELCOMPANY PHILADELPHIA
THE DETERMINATION OF SMALL AMOUNTS OF ALCOHOL AND WATER IN ETHER FOR ANAESTHESIA By
EDWARD MALLIKCKRODT, JR., AND A. D . ALT Received June 5 , 1916
A recent s t u d y of t h e methods for t h e detection of t h e common impurities in ethyl ether by one of t h e writers made i t seem desirable, on t h e grounds of completeness, t o have a method for determining quantitatively t h e amounts of alcohol a n d water in anaesthetic ether. S o claims for originality are made for t h e method given in t h e following pages since it is a development of one already used. Pure ether dissolves only about I per cent of water. Anaesthetic ethers i n this country never contain more t h a n 3 or 4 per cent of alcohol. Obviously, therefore, we are dealing with small quantities a n d extreme accuracy cannot be claimed. T h e results obtained b y applying t h e method t o five weIl-known brands of anaesthetic ether are given. Of t h e numerous methods proposed for t h e detection of water in ether, only t h e colorimetric procedure with rosaniline acetate,l t h e bluing of anhydrous copper sulfate when brought into contact with moist ether,2 t h e evolution of gas b y amalgamated a l ~ m i n u m ,and ~ t h e determination of t h e density before a n d after dehydration b y potassium carbonate,4 appeared t o be applicable t o t h e ,quantitative estimation of water in fairly pure ethers.5 Squibb’s Ephemeris, 2 (1884), 594. * Adrian, Mon. Sci., 44, ii, 835. Wislicenus and Kaufmann, Bey., as, 1325. Regnauld a n d Adrian, J . Pharm. et Chem., [3] 46 (1864), 193. 6 P r o f . Frankforter’s valuable test ( J . A m . Chem. SOC.,37, 2566) for the detection of water in ether was not published until a f t e r the experimental work in this paper had been completed. A few trials indicate t h a t i t is far more delicate t h a n the known tests. It would be desirable t o make the procedure quantitative if possible.
807
A set of standard ethers containing respectively a n d 1.0per cent water b y weight was prepared. Five milligrams of dried rosaniline acetate were placed in a dry test t u b e a n d I O cc. of ether added. T h e colors varied b u t t h e differences were not sufficiently marked t o allow placing ’some seven. ethers containing varying amounts of alcohol a n d water in between known members of t h e series using t h e eye t o judge t h e tints. Anhydrous ether containing 0.1 per cent of absolute alcohol gives a wine-yellow color different from t h e above colors. It would require considerable s t u d y t o perfect t h e method even if t h e t i n t produced b y alcohol could be shown not t o interfere. Ten milligrams of copper sulfate finely powdered a n d well dried at 2 2 0 ’ C. were shaken with I O cc. of each of t h e above s t a n d a r d ethers. After I j min. t h e copper sulfate showed no change from its original light gray color in ether containing 0.1 per cent water. b u t in ether containing 0 . 5 per cent water, t h e salt became bluish a n d t h e difference between t h e ethers containing 0.5 per cent, 0.75 per cent and I per cent could be detected. After about half a n hour t h e sample containing 0 . 2 j per cent could be placed in its proper position below t h e 0.5 per cent sample. The seven unknown ethers could be placed in this series more satisfactorily t h a n in t h e previous method, b u t t h e procedure is a t best only a n approximation, Contrary t o t h e experience of Baskerville,’ we h a d no success with amalgamated aluminum although considerable effort was spent upon this reagent because it is stated t o have t h e advantage of being uninfluenced b y alcohol. We have observed t h e evolution or disengagement of small bubbles even when t h e amalgam is placed in pure ether rendered anhydrous b y metallic sodium a n d ether containing 0.1 per cent of water showed no evident increase in t h e amount of gas liberated. It is not easy, therefore, t o distinguish what degree of bubbling indicates t h e presence of water. Bein,2 working with a dilatometer filled with pure ether at 2 j o , experienced great difficulty due t o t h e disengagement of small gas bubbles from t h e slightest jarring of t h e instrument. T h e amalgam offering many sharp points might be expected t o have a greater effect. I n passing, mention may be made of t h e fact t h a t t h e test for t h e detection of water i n ether b y shaking with carbon bisulfide is valueless, for, where alcohol is present, little or no turbidity is produced.3 We also tried subjecting ether t o a temperature of about -70’ C. produced b y carbon-dioxide-snow and acetone, in order t o freeze out t h e water as a hydrate of ether.4 The presence of about 0.1per cent of added water may be detected in alcohol-free anhydrous 0.1,0 . 2 5 , 0.j, 0.7 j
1
THISJOURNAL, 3 (1911), 312.
W. Bein, “Zur Ausdehung des Aethylaethers uud einiger mischungen des Aethers mit Aethylalkohol” Wissenschaftliche Abhandlungen der Kaiserlichen Normal-Eichungs-Kommission. Metronomischen Beitrage, Heft. V I I I , p. 11. Squibb (Sauibb’s Ephemeris, 2 (18841, 594) states t h a t absolute ether a f t e r the addition of 0.1 per cent of “watery alcohol” does n o t show the faintest cloudiness upon admixture of equal volumes of oil of copaiba or carbon disulfide. 4 Berthelot, Compf. rend., 86, 765; also Franchimont, Ber., 10, 830.
