REVIEW OF PAPERS ON ANALYTICAL CHEMISTRY (PROXIMATE) WHICH HAVE APPEARED DURING THE YEAR 1882. BY E. WAZLER, PH.D. MILKANALYSIS.-TOdetermine WATER,iNiLrynarm (Biederrnu?tn'x Ceentrkb. fur iigrirlult. Chem XI.,pt. 2 ) proposes to fill a calcium chloride tube with cotton wool, then to saturate the cotton with the milk, and to dry by drawing a stream of hot dry air through the tube. The I'AT may a l m be determined in the same sample by extraction with benml cw ethcr. 0. IIehner gives the result6 of expcrinients on the methods for milk analysis adopted by the Soc. of P u l ~Anal (Anulyst, VII., GO). In. determining WATER the operation was inore rapid on the water bath than in an oven. After drying for three hours an amount varying from 0.06 to 0.29 $ may b c > clriveii out by further heating. A temperature above 10o" C'. :Lpparwtly caiises decomposition and loss of solids not fat. For IjuTTEri FAT the Soxhlet apparatus removes about 0.2 $ more than boiling out with three or more successive quantities of ether. Sothing is gained by granulating the milk residue, by allowing the ether to act for :I long time, or by adding 10 $ absolute alcohol to it. Portions of the A S H are volatile at red heat. A. X a y e r states that the oil from ARTIFICIAL BUTTER has a much lower specific, gravity than that from natural butter. (Fuehling's Zandw. Ztg. XXXI., 92) I 7 1 he amount of COPPER NORMALLY PRESENT I N WHEAT is fitated by J v u n D.Berghe as 0.008 to 0.01 $ ( X e s Mondes, I., [3] 209). T O TEST BREAD FOR T H E PRESENCE O F ALUM, 11. Blyth (Analyst, VII., 16) proposes the use of slips of gelatine. The bread is crumbled into a vessel, a couple of slips of dry commercial gelatine placed with it, and distilled water added sufficient to cover the materials. On standing over night, the alum concentrates in the gelatine, and when dipped in fresh tincture of logwood, to which an equal bulk of 10 % solution of ammonium carbonate has been added the slips will dye blue if alum was present. When alum is not present, the slip becomes reddish brown, the tint being removable by soaking in glycerin. Experiments upon alumed bread seemed to show that much of the alum added remains as such after baking. Nearly all, if not quite all, of the alumina added as alum may be removed from the bread by soaking it in a 5 $ HCl. solution.
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I n EXAMINING TEA, J. Carter Bell (Analyst, VII., 7) gives the results of the examination of 58 samples, The variations were as follows :
.
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Per cent. of ash., . . . . . . . . . , . , . . . , . . . . 5.64 to 8.58 Per cent. of ash soluble in water.. . . . , , . 32.70 to 67.41 Per cent. alkalinity of ash (=K,O). , . . , . , 14.24 to 30.57
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In EXAMINlNG ROASTED COFFEE, A . Smethanz (Analyst, VII., 73) concludes from the examination of seven genuine samples, first, that moisture (loss at 100" C.) should always be first determined, The per cent. of ('crude fibre " is the best guide where chicory is the adulterant. The determination of oil, cellulose, ash (soluble and insoluble), nitrogen, and sp. gr. o€ the 10 $ infusion, are principally of service as checks on the work. The crude fibre was found to vary between 73.71 and 75.7 $, referred to the dry samples. I t was determined by boiling 2 gms. of the samples with three successive lots of water (100 cc. each), and finally washing on a tared filter until the washings were -olorless. For COLORIMETRIC ESTIMATION OF SALICYLIC ACID in articles of food, urine, &c., MM. Pellet and De G'robert (Revue des Industries, No.53, 1882)propose ferric chloride solution (sp. gr. 1.005 to 1.008) containing 0.5 gms. free acid per 100 cc. In testing butter by this method, 25 gms. are shaken with 5 or 6 drops sulphuric acid (of 30" B.) and 75 cc. benzol. The total volume is then made up to some convenient bulk (100 cc.) I t is then filtered, and 5 or 10 cc. mixed with the same bulk of water, and a few drops of the ferric chloride solution added, The mixture is gently shaken, the production of an emulsion being avoided, and the tint compared with that obtained in a standard solution. EXAMINATION OF WINES. General methods are given by J; Ntssler and M . Barth ( R e s . Zeitz. Anal. Chem. XXI., 43) and L.Xoesbr
(Chern. Zeit., VI., 306). For EXTRACT, the first named authors find that evaporation at 100" C . for three hours does not remove the glycerin. Some loss b y decomposition of non-volatile acids will be experienced, unless a known bulk of Ba (HO), solution is added. For genuine wines, the extract less acids is rarely under 1u $. Roeskr asserts that evaporation at temperatures above 80" causes both loss of glycerin and decomposition of the residue. He recommends evaporation at 60" C.in partial racuum.
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For added SVGARilTessZer uhnl l l a r t h Irefer a modification of Neubauer’s polariscope test. Cane sugar if present is partlnll!- 01wholly inkerted by the acids of the v ine on evaporating. C :imme1 has no optical effect. R o e s l e ~decolorizes u it11 boric black a11t1 uses t h e Fehling test. F o r FREE TARTARIC ACID A’essZer n n t Z Uurth evaporate a poi tiori, add alcohol until no further precipitatiou C ‘ I I S I I ~ S filter, , e\ aporate off the alcohol, add water, clarify by bone black, and then add one or two c’c. of Z0$ solution of calcium acetate.’ The anioiint of frec tartaric acid should not be over one-sixth thcl amount of thr non-volatile acids. IZutsZer firbt determines tartar 1,y adding 50 (*c,etbcr t o 1~ W. of win(>,allowing to stand 24 hours, wadling witli ether, dissoli iiig in boiling watcr and titrating. TIicn 10 cc of the Milie i< ncutializcd with standard KOH solution, 4c) cc. of the wine addetl, and 10 cc. of the mixtiwe treated as above. The excess of the acaitlity in the second case is due to frec tartaric acid. iITcssler t r i i t l Bwth also statc tliat the ASII should nt moit 1.4%. In sonic cases tile wines niay h ~e been i Eraiidulently diluted and the percentage of ash increased by use of SAIT. In such a case the ash does not readily blirn white. T o detect this fraud, the wine is decolorized by bone black and Volhard’s method used. T h e usual amount of Cl in wines is under 0.001$, the maximum 0 005~:. The last named authors also state tliat the maximum amount of CITRIC ACID iri genuine wines is 0.002 t o 0.003 per ccnt , imt illat acid is frequently added as such or i n tamarinds (w111cli contain 13 5 $ T o determine it, 100 vc. of the wine are eiaporateci to 7 cc., cooled, the soluble portion cxtractctl I q alcohol (of 80$) the residue diluted to 20 cc.,purtZy ~ieutializecl with niilk of linic, (Cor red wines bone black is also aildccl :it thic I’oini) filtcrc~l,diluted to 100 cc., and the citric and tartaric acidq w1)drnted 1)) ;kboiit one cc of ntutral lead acetate. From thi\ conibination the lend i3 wparated by agitation with II,S water, awl filtering. After removing the H,S, lime is added to render the bolutioii alkalirle, and after filtering it is made slightly acid with acetic acid and allo\ved to stand t o sqxirate the calcium tartrate. In the filtrate the acetic acid is expelled by heat and the wlution is finally boiltvl until the calcirtm citrate separates in crystalline form when it is filtered and wcighell lZoesler determines the GRAVITY preferably by Sl-mngel’. p\i linometer ; A L C O H O L by distilling off two-thirdi, making the distillate up to the
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original volume and taking the gravity ; TANNIC ACID by distilling off the alcohol, making up to the original volume, agitating with bone black, filtering, and applying Neubauer’s modification of Lmwenthal’s method, (permanganate and indigo carmine) ; ACETIC A C I D by adding baryta hy(lrate, distilling off alcohol, and then distilling with phosphoric acid (Kessel-Neubauer’s method) ; GLYCERIN by evaporating (100 cc.) down to one-third, rendering slightly alkaline with slaked lime, evaporating to dryness, extracting with alcohol, evaporating this again to dryneqs and extracting the glycerin from the residue by a mixture of alcohol and ether, (Seubauer-Reich artlt’s method) ; and NITROGENOUS CONSTITUESTS by evaporating 10 to 20 cc. in a thin glass vessel, pulverizing rezidue Slaw and all, and making a comhubtion as usual. F o r TAXSISA X D CENOGALLICA C I D , R .Jeen)i(C’owtes Brntl. XCIV. No. 11) evaporates 50 to 100 cc. down to small bulk-adds dry precipitated silica, dries at GO to ?O”C., extracts with ether containing a little hydrochloric acid, evaporates the ethereal solution, and dissolves in water, 111) to the original bulk. I n 10 cc. of this solution the combined acids are determined by titrating with iodine, and in the remainder the mnogallic acid is determined (after shaking with rasped hide to remove tannin) by titration again with iodine. For GLYCERINE in sweet wines E. Borgrnwnn ( B e s . Zeits. A n d Chem., XXI, 239) evaporates 100 cc. t o a syrup, extracts the residue with 100 cc. of absolute alcohol, and then adds 150 cc. of ether. The sugar settles to tlie bottom, leaving the glycerine in solution. For R E D COLORISG JIATTERS .7: Be G w o t ( A e p e r t der rlnalyt. C/~.cm,11, 95) adds to a wine or other liquid to be tested, one volume chloroform ancl three volumes absolute alcohol, and agitates briskly; three volumes of distilled water are then carefully added without shaking. Many coloring matters separate at the point where the two liqiiicls are in contact. A few, as, for instance, fuchsin, pa‘s into the chloroform. By the manner of separation or the coloration imparted to one or both liquids, many of the coloring R E D I N WINES matters may be identified. To detect BORDEAUX C. T / L o ~ ( Chem. / s Zeit., VI, 244) precipitates the wine with barium hydrate-filterb-reinoves the excess of barium by ammonium carbonate, ancl in thc filtrate by evaporation, ignition, etc.; tehts for the 1)reqence of wlphnric acid arising from the presence of a sulpho compound. X . Gr6ic’r’v(rtZ (Joz~m. de PhcwiiL. et d e C/~im.,May 1882) tests for the same coloring matter by (11-eing silk with the wine. The natural coloring matter gives only a violet or lilac
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shade, which turns grecnihh with ammonia, while the Bordeaux red dyes the silk a garnet shade, turning darker with ammonia; also a drop of genuine wine let fall on a lump of chalk moistened with alum t;oliition gives a violet gray spot; whereas, if Bordeaux red is present, n red h t a i n appear*. F: MzisciiZii~and C. z l / ) i t / t i ) y (Ziepert. A n a l y t . Chem., 11, 142) find that the riaturJ WINE^ o b A JIAII TEAK contain but little alcohol and much ncaid, birt contain more ;tsli, extractive and phosphoric acid thiiri cveii tho h t iiics of a gobil year. b'or S ~ L I ' H L - R OA(~ 11) ~ ISW I X E ~B. 3hz.s (Rer. Cheu2 Ges., XV, 1,54) tlistil. off ,iboiit half of a mea\ured quantity in a current of CO, into :ibiill) tnlw containing iodine wlution, when the snlphuric nvitl fornictl may l w tleterniined by BaCI, L. Lieberniari ( I l e r D.( , ' / L ~ L Gcs., . XV, 439) tli3tils in a similar manner, oxidizing by the i i c c o f IISO,. T h e 1:t.t-named author makes a qualitati\ e test upon tlic distillate b y usiiig iodic8 acid an11 cliloruforiil. A small amoiiut of SO, gives tlie violct coloration t o thc chloroform; lavger :mioritits n yellowisli brown. OIL\, S-( .--Tu rli.tingiiich between OLIVE AND COTTOS SEED OIL M. % e c ~ h i m X O ) L Ma! ~ ( S13, , 1882) agitates 5 cc. of the oil with 10 of (*oIorle*snitric wit1 (sp. gr. 1.4), and then allows It to staiill for f i \ o 01' \ i \ miniitc> Piire olivt, oil will then appear a light ayh gray coloi,, with '1
