摘要:

TEE ANALYST. NOVEMBER, 1896. NOTE ON THE CONCENTl3ATION OF CONDENSED MILK. BY ALFRED H. ALLEN. IN the case of unsweetened condensed inilk the nietliod of calculating the concen- tration which has been effected, and the water required to dilute the product to its original strength, is of the simplest possible character. But in the case of sweetened condensed milk certain factors exist which, if not taken into account, may lead to a serious miscalculation as to the concentration. Thus, the ‘‘ Milkmaid ” brand, which is a typical and well-known make of sweetened condensed milk, contains, according to the analysis of Pearmain and Moor, 3‘7% per cent. of milk-solids, 38-7 per cent. of cane-sugar, and 23.7 per cent. of water. The milk-solids are three times as high as in uncondensed milk of good quality, which may be taken as containing 1 2 5 per cent. of solids and 87.5 per cent.of water. The water originally associated with 37.5 per cent. of milk-solids would be 87.5 x 3 = 262.5, whereas the condensed milk contains only 2 3 . i parts of water for the same amount of milk-solids. Therefore, 238.8 parts of water out of 262.5 originally present, or about ten-elevenths of the whole, n u s t have been evaporated. But the addition of cane-sugar dilutes the milk thus concentrated, so as to produce a finished product containing only three times the proportion of milk-solids present in uiicoiiceiitrated milk. Hence the additmion of twice its weight of water to the condenstad milk will reduce the milk-solids to their original proportion. But, as the dilution is in practice effected by measure rather than by weight, the number of measures of water (W) required to reduce one measure of condensed milk to its original concentration may be found by the following equation : Measures of water re- Milk-solids in condensed milk (C) x sp.gr. (G) Milk-solids in diluted milk (U) - 1. quired for dilution (Iv) = Sweetened condensed milk of the character of the “ Milkmaid” brand has a If this figure be accepted, and the milk-solids of the ~ specific gravity of about 1-28. original milk be taken at 12.5 per cent., then the above equation becomes : W = 1.28- 1 ; or w=o-i024c - 1. Taking as an example the ‘( Milkmaid ” brand with 37.6 per cent. of milk-solids, somewhat less than three measures of water will reduce it to the priinary con- centration : 12.5 W = (0.1024 x 37.6) - 1 = 2.85.282 THE ANALYST. Similarly, the percentage of milk-solids which will be contained in a diluted condensed milk may be found by the equation : Milk-solids in diluted niilk (D) = -- 1-28C w +1’ Thus, taking the Milkmaid” brand, if the milk be diluted with the niaximutn quantity of water directed on the label, namely, 14 parts, the diluted milk will contain 3.21 per cent.of milk-solids : 1.28 x 37.6 = 3,21. 14+1 If for the value of C in the above equation the percentage of fat (3’) in the condensed milk be substituted, the proportion of fat in the diluted milk will be found. I n the case of the “ Milkmaid ” brand, diluted to the maximum as before, this will be : 1.28 x 11.0 14.08 . - =0-94 per cent.of fat in the diluted milk. i 4 + i - 15 The foregoing equations give the dilution necessary to bring the parts of milk- solids per 100 measures of the diluted condensed milk to that contained in the original milk before concentration. If unity, when it appears in the above equations, be multiplied in each case by the specific gravity of the condensed milk ( = 1-28), the equations will give the dilution necessary to yield a product containing 12.5 per cent. by weight of milk-solids. The following table shows the proportion of fat which would be contained in representative brands of sweetened condensed inilk if the contents of the tin were diluted with the amount of water directed on the labels. Thecalculations have been based on the assumption that the condensed milk before dilution had in each case a specific gravity of 1-28.This is the result of experiment on typical preparations of the kind. ~ ~ 9 B C D E F G H 1: J K L - Rraiirl. Alderney Arcadia Cowslip Devon Far in Fourpenn ... -.. ... ... . . . Full weigll. , . . Goat ... ... Milkmaid ... Nestle’s Swiss Rose ... ... Threepenny . . . Nrimher of parts of Water recornmended to be added to one part of Condensed Milk for cooking and ordinary use. 5 to 6 4 to 5 4 to 5 4 to 5 4 to 5 4 to 5 4 to e5 3 4 to 5 4 to 5 4 to 5 4 to 5 I’ercentage by weight of Fat in Milk thus diluted. 2-32 to 1-94 1.95 to 1.63 0.34 to 0.28 2.06 to 1-72 0.03 to 0.02 2.52 to 2.10 2.81 to 2-34 0.87 2.66 to 2-22 3.30 to 2.77 3.00 to 2.50 0.07 to 0.06 Nnmber of parts of Water recommended to be added to one part of Condensed Milk for infants’ use. 6 to 8 7 to 14 Not stated G to 14 Not stated 7 to 14 7 to 14 Not stated 7 to 14 Not stated 7 to 14 Not stated Per centage by weight of Pat in Milk thus diluted. 1-94 to 1.52 1.24 to 0.68 Not stated 1-50 to 0.71 Not stated 1.60 to 0.87 1.79 to 0.97 Not stated 1.69 to 0.32 Not stated 1.91 to 1.04 Not stated

ISSN:0003-2654    

DOI:10.1039/AN8962100281

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

THE ANALYST. 283 THE RELATIVE COMPOSITION O F MILK, CREAM, AND SKIMMED MILK. BY NORMAN LEONAND, B.Sc., F.I.C., AND HARRY M. SNITH, F.I.C. -4s a layer of cream gradually forms on the surface of milk, the composition of the liquid varies at different levels. The upper layers contain a larger proportion of fat, and a smaller proportion of other constituents, than the original milk, while in the lower layers these conditions are reversed. If the change which takes place during the rising of the cream consist solely in the ascent of fat globules, it is clear that the relation between the amounts of water and of solids-not-fat will be the same in the cream and in the skimmed milk as it was in the original whole milk. The lower layers, in fact, may be regarded as an aqugous solution of milk-sugar, casein, and other substances, containing little fat in suspension, while the upper layers consist of a precisely similar solution, with a larger amount of suspended fat.Wanklyn, in his book on milk analysis, adopts this view, and gives a few perhaps not very conclusive figures in support of it, He states, however, that rich town-fed milk is apt to throw up a little casein with the cream, and points out at the same time that any imperfection in the analysis of cream tends to raise the solids-not-fat. H. Droop Richmond, in giving results of analyses of cream, has also referred to this point on various occasions. Devonshire ” creams there seems to be little doubt, judging from the inany recorded analyses, that there is a larger amount of solids-not-fat, in proportion to the water, than is to be found in ordinary whole milk.The-heat commonly applied to assist the separation of these rich creams may possibly be the cause of this ‘‘ incipient coagulation.” The question is obviously of some importance to those connected with the working of the Sale of Food and Drugs Act; for if casein be thrown up with the cream, a sample of milk taken from a vessel, the contents of which have been imperfectly mixed, cannot by analysis afford any trustworthy evidence either as to the addition of water or deficiency in fat. If, however, the relation between the water and the solids-not-fat be undisturbed, the analysis will show the presence or absence of added water, although, of course, no conclusion can be drawn as to the fat.I t was a discrepancy between the analyses of samples stated to have been drawn froin the same churn at different times which induced us to make some experiments with a view to determining whether Wanklyn’s theory held good or not. That it does hold, under ordinary conditions and so far as the usual analytical methods are capable of deciding, is, we think, proved by our results, which are given in the following table : In the rich so-called284 THE ANALYST. Calculated on Water. - A ... A 1 4 ... ... A 2 3 . , . ... A 3 4 ... ... 9 4 3 ... ... I3 ... B 1 r!, ... ... B 2 -; ... ... B 3 /; ... ... C ... c 1 ; *.. ... c 2 ;- ... ... Total Solids. 12-66 15.95 11.05 13.67 10.63 9.60 16-44 8-32 7.67 11.60 20.10 9.28 Fat. Solids-not - I Fat. 3.68 7.37 1.91 4-83 1.58 3.07 10-16 1-68 0.91 2-98 12.39 0.60 8.98 8.58 9.14 8-84 9-05 6.53 6-28 6.64 6-76 8-62 7-71 8-68 Ash.0.75 0.71 0.78 0.74 0.76 0.54 CI.45 0.54 0.55 0.70 0.64 0.78 Water. 87.34 84.05 88-95 86-33 89.37 90.40 83.56 91 -68 92.33 88-40 79 *90 90-72 Solids-not- Fat. -I 10.28 10.21 10.28 10.24 10.13 7-22 7.52 7-24 7.32 9.75 9-65 9.57 Ash. 0.84 0.84 0.88 0.83 0-85 0-60 0.54 0.59 0.60 0.79 0.80 0-86 The samples of milk were allowed to stand in separators for about eighteen hours at the temperature of the laboratory. Measured portions were then drawn off successively from the bottom and submitted to analysis. In the first experiment a milk yielding on analysis the results given at A (see Table) was thus divided into two portions, an upper portion (9 1) forming one-third, and a lower portion (A 2) forming two-thirds of the original volume.I n a second experiment, made with the same milk, the upper and lower portions (A 3 and A 4) formed respectively two-thirds and one-third of the whole. Another sample of milk'(B) in the third experiment was divided into three portions, upper, middle, and lower, each of which was analysed; while in the last experiment on a milk (C) only the upper and lower portions, each forming one-seventh of the whole, were examined. The numbers in the seventh and eighth columns of the table are obtained by dividing the percentages of solids-not-fat and of ash respectively by the percentage of water in the various samples, and multiplying the quotients by 100. The numbers in the seventh column are practically identical in each of the three sets of analyses.What variations there are exhibit no regularity, and are such as might be expected to be due to experimental error. The figures in the eighth column show a less satisfactory agreement. In each case the skimmed milk yields a higher proportion of ash than the cream. This is probably due to the subsidence of suspended mineral impurities (dust) in the milk. The conclusion we draw from our experiments is, that at the ordinary tempera- ture no disturbance of the relation between water and solids-not-fat takes place when milk is allowed to stand at rest, even when the upper layer contains twenty times as much fat as the lower. We would further suggest that, ia estimating the amount of added water (if any) present in samples of milk containing an abnormally high or low proportion of fat, it is desirable to take as a basis for the calculation the percentage of solids-not-fat in the water instead of in the i ? d k . The percentage ofTHE ANALYST. 285 solids-not-fat contained in the water of milk of average quality is, of course, taken as a standard for comparison. We have to express our thanks to Dr. Stevenson, in whose laboratory these experiments were carried out.

ISSN:0003-2654    

DOI:10.1039/AN8962100283

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

THE ANALYST. 285 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Potaesium Chromate as a Milk Preservative. J. Froidevaux. (Jozw. Phnrin. Chiin., 1896, 155-158.)-The author describes experiments made to determine what amount of neutral potassium chromate is necessary for preserving milk for an appreciable time, and finds that at least 0.2 gramme per litre is required, an amount which gives to the milk an intense and absolutely abnormal colour. He considers that the proportion of 2 grammes to 50 litres of milk, which (according to DenigBs) the retailers of Bordeaux employ, is altogether insufficient to retard coagulation. With regard to the detection of chromates in milk, the method of Denighs (addition of 1 C.C. of a, 2 per cent. solution of silver nitrate to 1 C.C.of milk) is satisfactory when the amount of chromate exceeds 0.01 gramme per litre ; when below this the colour is inasked by the precipitated phosphates. The following method is preferred : The ash from 10 C.C. of milk is dissolved in a few drops of water acidified with nitric acid, neutralized with magnesium carbonate, and the silver nitrate solution (preferably 20 per cent.) added. As a control test the ash from 10 C.C. of milk is taken up in a few drops of water slightly acidulated with sulphuric acid, and tincture of giiaiacum added little by little. An intense blue colour, which rapidly disappears, is produced when chromates are present. The reaction will detect 0.02 to 0.03 gramine of chromate per litre. C, A. 1\11. Detection of Formaldehyde in Milk.C. Denigks. (Ihdz. Soc. Phamb. dc BOi'dCQ21,X, July, 1896, p. 212 ; through A m . t7c Clzinzic Bitnlyt., i. [16], 316.)--The colour reaction (red) given by bleached fuchsine with forrnaldehyde may be distin- guished from that due to casein and albuminoids by changing into blue on the addition of hydrochloric acid, whereas the acid destroys the colour in the other case. To perform the test 1 C.C. of fuchsine solution decolorized by sulphurous acid is added to 10 or 1 2 C.C. of milk. After 5 or 6 minutes 2 C.C. of pure hydrochloric acid are added, and the mixture shaken up. The violet-blue coloration indicating formaldehyde will be appreciable, even when only 2 or 3 centigrainmes are present per litre. In the absence of this body, the mixture will become yellowish-white. The deligacy of the test maybe heightened by diluting the milk with an equal volume of water, adding 3 to 4 drops of glacial acetic acid, followed by 5 C.C.of mercuric iodide solution; then agitating and filtering, and applying the fuohsine test to the clear filtrate, the acid being added after an interval of 10 minutes. I n this way a286 THE ANALYST visible coloration will be obtained in the case of 1 centigramine of forinaldehyde per litre of milk, especially if the liquid be examined by looking down the tube. The colour may be compared with standards corresponding to known percentages of f orinaldehyde. The reagent is prepared from 40 C.C. of a 3 per cent solution of fuchsine, 250 C.C. of distilled water, 10 C.C. of 40" B. sodium bi-sulphite and 10 C.C.of pure sulphuric acid, The mixture will be suficiently decolorized for use after standing a few hours. c. s. Detection and Estimation of Sodium Bicarbonate in Milk. L. Pade. (AWL tlc Chinzie Ancdyt., i., [17], 328.)-The best method of detecting the presence of added sodium bicarbonate in milk is by determining the alkalinity of the soluble ash, but this method is insuficient for a quantitative determination, since the greater portion of the sodium enters into combination with phosphoric acid during the process of incineration, necessitating the titration of the phosphoric acid also. The ash from 25 C.C. of milk is dissolved in water, and the alkalinity of tlie solution determined by <c normal sulphuric acid, the volume of which, multiplied by 0.0084 gives the quantity of unaltered sodium bicarbonate in the 25 C.C.; or the percentage inay be obtained direct by multiplying by 0.0336. After addding to this neutral solution about 2 C.C. of a 10 per cent. solution of sodium acetate slightly acidified with acetic acid, the phosphoric acid is titrated by uranium acetate solution, standardized to correspond bulk for bulk with a solution containing 3.11 grnmmes of sodium-ammonium phosphate per litre, so that 1 C.C. of the uranium solution is equivalent to 0.01 gramme of sodium bicarbonate per 100 C.C. of milk. Cochineal tincture forms the most delicate indicator. Proceeding in this manner, the author has obtained results not exceeding by more than 0.008 grainme per 100 C.C. of milk the quantity of bicarbonate added.c. s. The Detection of Borax in Butter. Planchon and Vuaflart. (JOIW. Pharm. Chinz., 1896, 49-51.)---Twenty gramines of thp, butter are iiielted in a basin, dissolved in 10 c.c., of petrolemii spirit, and the solution poured into a separating funnel. The basin is rinsed out into the funnel first with 10 C.C. of petroleuin spirit, and then with 10 C.C. of water. After bcing well shaken the liquids are allowed to separate, and the aqueous layer, together with the supernatant film of casein, run into a platinum basin, evaporated to dryness and incinerated. The ash is fused with 0.5 gramme of pure dry potnssiuiri carbonate, a very minute quantity of copper oxide added, and the fusion repeated. On cooling, a blue colour, more or less pronounced, denotes the presence of borax.Pure butter treated in this way gives only a gray or reddish-gray colour. Phosphates and fluorides do not give the coloration, but silicates dissolve the copper oxide and yield a pale blue mass which, however, is quite distinct from that produced by borax. As regards the sensibility of the reaction, a distinct colour is invariably given with two parts of borax per 1,000, and sometimes with 1 per 1,000, while by taking a larger quantity of butter still smaller proportions may be detected. The shade varies from greenish to violet-blue.THE ANALYST. 207 The method has not proved very sathfactory in the case of milk, wine and beer. With milk the difficulty of fusing the ash inakes it necessary to increase the amount of potassium carbonate, and the fused mass is then too voluminous to show the colour plainly.The difficulty with wine and beer is that the ash alone when fused with potassium carbonate produces a green coiour, which is probably due to a trace of manganese. C. A. M. Examination of Butter. C. Asschman. (Chiii. Xeil., 1896, ss., 723.)- -By the following proccss inrtrgariiie iiiay readily 11s distinguished from genuine butter. 5 patnines of tho sample are saponified in a basin in 10 C.C. of 95 per cent. alcohol and 2 C.C. of 60 per cent. potash, and the soap is dissolved in about 150 C.C. of water. The solution is poured into a 300 C.C. flask provided with a iiiark at 200 c.c., 4 C.C. of 1 : 3 sulphuric acid run in, and when cold iiiade up to the lower insrk ; 60 C.C. of ether are added, the whole well shaken two 01’ threc times, the flask closed with a cork, and stood in watcr at 16” C.30 C.C. of a 30 per cent. solution of cominon salt (sp. fir., 1.175) are put into a stoppered tube about 40 ciii. long, holding 100 c.c., 8 C.C. of decinormal potash, :md 20 C.C. of the above ethereal solution added, and after a thorough agitation the inixturc is set aside for one or two hours till separation has taken place. On examination the ether will be found to contain a layer of inatter insoluble in both liquids which, with genuine butter, will not bc more than 20 or 25 mm. thick : hut in the case of innrgarino will be 60 or $0 iuio., if indeed the whole of the ether be not filled with it. F. €3. I.. Conrributions to the Analysis of Honey. E. Besckmann.(Zed. aicnl. CIim., L691i, sssv., 268-2S4.)--1fter a short suiniiiary of work done by others on this subject, thc author describes experiments niade with the object of detecting ‘‘ staxch syi-up ” anti coniiiiercial destrin in honey. Dctccticur hi m w i i . r (2t’ X?tl:?jI I /colicd n i i t l Iodiiic SoIi&tioiz.-OJ1 treating diluted (‘ starch syrup ” with methyl alcohol (or ucctoue) a white precipitate was obtained which could be dried by repeated evaporation on the water-bath with ethyl alcohol. The dextrin (about 31 per cent.) was a whito non-hygroscopic powder with a slightly sweet taste. When tested with E, solution of iodine in potassiuui iodide it gave the reddish-brown colour of eythro-destrin. In the manufacture of the syrup the iuversion of the starch by the acid is not carried beyond the point where iodine gives the red reaction.Honey treated with the above reagents only gave a light flocculent turbidity which did not settle on the walls of the vessel like the precipitate froin “ starch syrup.” A mixture of honey and dextrin gave a large precipitate, and this (as well as the origiiial honey) gave an intense red or violet colour with iodine solution. 1)iriZysis qf “ Stctrcli S I J I ~ ) ” aizd Iloiuy.-Hii,nle’s iiiethod (.ANALYST, svi., 79) was employed to see whether the substances precipitated by methyl alcohol were also dilbsible. It was found that throughout the operation portions of the dextrinous bodies passed through the iiiembrane. The author considered that no sharp separa- tioii of houey-dsstrins and starch-dextrins was possible by the method, although thc288 THE ANALYST.time taken by honey to coinpletely diffuse was considerably shorter than that required by the starch products. When dialysed with water at B higher temperature, 50-70" C., the " starch syrup " diffused more slowly thaa the honey, but in this case also the whole of the constituents eventually passed through the membrane. Dialysis with warm methyl alcohol gave the following results : 5 gramrnes Honey-k Honey 10 grenimes. .7 graniriies Starch Syrup. 10 grammes Syrup. Residue : Xfter 50 hours -1fter 103 hours dfter 103 hours 0.0 gramme. 2.2 grammes. 4.8 grammes. Consec ii t ivc t wdnzcnt 20 itlL iizctIz!jl ( I i d . c t hy 1 (1 lcol~ols,- (1) SICLTC 11 sgrup. After filtering off the methyl alcohol precipitate, the addition of ethyl alcohol to the filtrate produced a fresh precipitate, diff'ering from the former one in being hygroscopic- 80 grammes of syrup dissolved in SO C.C.of water gave, with methyl alcohol, a precipitate of 25 grammes = 31 per cent. The filtrate, after evaporating the methyl alcohol and adding ethyl alcohol, gave 33 gramlnes = 41 per cent. (2) Conqer houey, [u]D= + 16.9". When treated with ethyl alcohol as above yielded 50 per cent. of a strongly hygroscopic substance. Conifer honey was practically soluble in methyl alcohol. (3) Solid !~lztcosc. I n this the starch had been inverted until complete disappearance of the red colour with iodine. Methyl alcohol produced only a slight turbidity, but ethyl alcohol precipitated 46.3 per cent. of a very hygroscopic destrinous substance.('? Gallisin. Iso-maltose.) Fewiacii tability of the (7i.fereizt c7cxtl.ilzs.--,~lthough the dextrins of honey were more fermentable than those of " starch syrup " or glucose, the author considered that no certain conclusion could be based on this alone. None of the residues left after fermentation gave a red colour with iodine-a proof that the erythrodextrin was further hydrolyzed. Pw.cipitc&o?z with nzctl~y 1 ulcolzo 1 c( iicl bur.ytch.-The dextrins of honey behaved differently to those of '' starch syrup," etc., in the formation of destrinates, and on this property the following test was based : 5 C.C. of honey solution (20 grammes in 100 C.C. water) were mixed with 3 C.C. of a 2 per cent. solution of barium hydroxide, and 17 C.C.of methyl alcohol added. On shaking, the solution remained clear, or only slightly turbid when pure honey was present, but with starch-dextrin, L L starch syrup " or glucose, there was a considerable precipitation. For a quantitative estimation the amount of honey taken was increased to 50 grammes, the inethyl alcohol added rapidly all at once to avoid deposition on the glass, the liquid well shaken once, and the precipitate filtered on to a tared asbestos filter, washed with methyl alcohol and ether, and dried at 55" to 60' C. Excessive shaking was avoided to prevent the action of air on the precipitate, and it was found that the quicker the working the more accurate the results. Only in exceptional cases did the presence of sulphates or phosphates in the honey interfere with the results, and these were then separately determined and allowed for.The ineaii results obtained in this way, calculated on 1 gritinme of the substance, were : Dextrin, 0.916 gramme ; L L starch syrup," 0.455 gramme ; glucose, 0.158 gramme. The amount of precipitate produced was in each case nearly proportional to the concentration of the solution. The admixture of conifer honey with the aboveTHE ANALYST. 289 three substances in the proportion of 90, 75, and 50 per cent. did not increase the amount of the precipitates, but, on the contrary, somewhat diminished them. Various pure samples of natural honey, rich in dextrin, were tested in this way : L4pp1e HOTZC~.-[U~D = - 12.2". Dextrin precipitated by alcohol (Kiinig and Karsch) = 113.7 per cent.Baryta precipitate : 5 C.C. of 10 per cent. solution gave 0-0044 grainme. 5 J J 7 , 1, 0.0072 ,, CT/~iDelLiJ'cr Hoiiey.-Dark, with green fluorescence. [ a ] ~ = - 4.610". Dextrin =29.1 per cent. Baryta precipitate : 5 C.C. of 10 per cent. solution gave 0.0148 gramme. 5 J J 20 J J ,, 0.0230 ,, C'oizz'f'er Hoizt:y.-Slightly resinous smell. [ U ~ D = + 16.9". Ilextrin = 41.5 per cent. Baryts precipitate : 5 C.C. of 10 per cent. solution gave 0.0132 gramme. 5 ,, 90 ,, ,, 0.0848 ,, Hence the author concluded that under the most unfavourable conditions one could recognise the addition to conifer honey containing over 40 per cent. of dextrin of from 5 to 10 per cent. of starch dextrin, from 10 to 30 per cent. of starch syrup," and of 30 to 40 per cent.of glucose. With ordinary honey, like the above apple honey, adulteration would be much more easily detected. By a combination of the fermentation and precipitation methods very small addition of starch products would be detected in doubtful cases. Honey zvitlz HoiLey-dsw.--On treatment with iodine solution honey-dew gave but a, slight colour, but otherwise behaved like '' starch syrup." Methyl-alcohol precipi- tated dextrins which deposited on the glass, and large barium precipitates were obtained. (Cj: ANALYST, xx., 16.) Hone!/ frowt Bees j c d (JIZ " S ~ I W C I L Symp."-The honey thus obtained behaved in a similar way to normal honey, showing that the bees can so modify starch dextrins that they assume the character of honey dextrins. Detectiou oj' Cniie-szLynr n i ~ d XoZusse.s.-Bees cannot completely invert cane-sugar, which is therefore a norinal constituent of honey.What amount is allowable is uncertain, since Utescher gives 5 per cent. as the maximum, whilst Hefelmann and the Swiss chemists allow as much as 16 per cent. For detecting molasses the author used basic lead acetate and methyl-alcohol, which gave white precipitates attributed to the presence of raffinose. I t was found that with honey the conceiitration must not exceed 25 per cent. In this way the addition of 10 per cent. of molasses to honey could be easily detected. c. A , 11. Detection of Foreign Colouring Matters in Red Wines. A. Belar. ( X c i t . ,lmzL. Client., 1896, ssxv., 322, 3dY.)-Owing to the fact that many of the aniline colours are soluble in nitro-benzene, whilst the blue arid red colouring matters of plants are quite insoluble, the former can often be detected in red wines.About 3 C.C. of the wine are gently shaken with an equal volume of nitro-benzene ; when iii the presepce of fuchsin the nitro-benzene assutnes a red colour. Should it remain colourless, the shaking is repeated more vigorously, and the emulsion got rid of by290 THE ANALYST. gently warming. By using a sufficient quaiitit,y of nitro-benzene fuchsin may be coiiipletely extracted from a wine and quantitatively esbiinated. Methylene hlne is estracted from an aqueous solution by nitro-benzene, to which i t imparts an emerald green tint, while rosanilin, purpurin and safranin dissolve without changing their colour.Eosin is largely soluble, giving a wine-red colour, but tile soliltion does not fluoresce. The insoluble portion has a yellow tint, as has also the portion of rosolic acid not estracted by ni tro-benzene. Indigo carininc, on the other hand, behaves like the blue colouring inatters of plants, b?iiig q u i k insoluble i n nitxo-benzene. c. A . M. Tho Ainouiit of Copper nbsorbed by Vcgetablos from a Coppery Soil I-;. B. Lehmann. ( A re//. I l y y i c i i c , lMG, xxrii., 1 ; through CIici;~. Z c i t . ICcp., lS%, 2 45.)-The author still maintains tliat Vedridi’s results (ANALYST, sxi., 235) arc too high. ITe now burns his samples with or without the addition of sulphuric i i c i d , dissolves the ash i n nitric acid-fusing any residue with soda and saltpetre, iil issolving in acid, and inixing the two solntions-precipitates with sulphuretted Iiydrogen, ignites the> sullihide, dissolves in hyclrochloric acid, and determines the ropper colorinietricnlly as before.H e finds that the aniount of copper in the vegetables tliminishes rul)idly with the distance from the source of contamination, and that the species of plant has far less irifluence than the quantity of copper in the soil on the amount taken up. I n moody plants the bark contains most metal, aud the wood least. Hnlf of t8he copper is soluble in water, but it exists as some crganic compound, perhaps with albuiiiin, wliich prevents its being detected in the solntion by ordinary reagontq. Tlie iiletnl a1)pears neitlier to proinote nor to hinder the growth of the plants.F. 13. L. Rspid Xstinzatioii of Zii:c iii Ahrticles of Food. Jaake. ( c % ? 7 1 ~ Zcif., I N ( ; , \x., 800.)--Fifcy to 109 gr~iiiiiies of tlie substance ( P . ! / . , apple rings) art3 cut LIP into i)iec3s, dried for thLee 1:ours at 1 2.jd C., aiid then pwderecl. 25 C.C. of 1-31 nitric acid and 10 C.C. of st,i.oiig rulphuric acid are a c l d d , and the whole is ignited for about lour Iiours in a coverdd platinum crucilh at a barely visible red heat. The resulting \\bite ash is moistened with nitric acid, evaporated on the water-bath, taken up in \i ater, iiltercd, the iron, etc., removed by the aniiiioniuiii acatate process, and finally -lie zinc in tlie filtrate is precipitated twice as sulphide. Twelve analyses of samples Goiitaining 10 to 50 inilligraniiiies of %no are quoted: the amount recovered varying fro111 98.8 to 104-5 (niean 100.41) per cent.(?I. A l ~ < - i ~ A ~ ~ ~ i ~ , xx., %jl.) F. H. L. Adulici-ation of Cantharides. M. Cabannes. (lj!ill. I’hu?*??t. du Szid-ldsl ; through Jour. Plz(ii*iiL. C/ii77~., l S N , 310, 31 1.)-It is stated that cautharides are lrequently adulterated with insects of similar appearance. One saniple was found l>y the author to consist of four varieties : C‘n7tthnri.s vcsicntoria (25 per cent.) ; 6’. togntn (45) ; SgZlilin ~?iai.trr2,iii2ctntcr~t~ (20) ; and C‘etonia n i i m t r o (10). Of these the two last were completely devoid of vesicating properties, whilst c‘. togntcc, only conTHE ANALYST. 291 tained 0.27 per cent. of cantharidin, iristead of 0.50 per cent., as in the genuine beetle.This variety, which has its origin in Turkestan, is larger than C. *uesicatorin; its abdomen is more tapering, and it has on the elytra a longitudinal yellow band rarely reaching the extremity. When applied to the skin it only produces a slight redness after the lapse of Iwenty-four hours. The C. rcsicutoria of the above-mentioned mixture did not contain the amount of cantharidin required by the c(odcx, having only 0.4115 per cent. Instead of 0-50 per cent. c. A. M. The Detection of Acetanilide. F. X. Moork. (dr~er.. JOZIr72. PILc1TI)b., 1896, lxviii., 389-393.)-To obtain a lllethod for the detection of acetanilide ill closely allied synthetic remedies the author studied the action of bromine on 1 per cent. solutions of the various compounds. When bromine-water was added drop by drop 60 long as the colour was discharged, and the liquid stirred, after five minutes the results were : C.C. Bromine- Appearance. Water added. [ Yellow liquid, white pre- Colourless liquid, white pre- ... ... ... ... Acetanilide ' - 0 1 cipitate. Nxalgin ... 0.8 { cipitate. Methacetin, C,€I,jO~H,,)N€r(COCH:~) . . . ... 1-8 Yellow liquid, becoming P hen ace t i n ... ... ... ... ... 0 G colourless, pink, finally Pheiiocoll ... ... ... ... ... (2-0 1 red-browny slightly turbid. f Liquid like above; distinct Lactophenin, C,,H,(OC,H,)NH(CO~HOHCH,) 1.2 white precipitate. Colourless, slightly turbid On shaking with a light petroleum benzine, the exalgin precipitate readily dissolved, the acetanilide precipitate slightly dissolved, whilst the lactophenin precipitate was insoluble.Kther was not so satisfactory, as it dissolved all the precipitates. Since a precipitate could be obtained with a solution containing 1 in 9,000, the bromine test seemed to be applicable to the detection of not less than 5 per cent. of acetanilide in all the remedies except lactophenin. The isonitrile test was modified so as t o destroy the odours due to other remedies. 0.1 gramme of methacetin, phenacetin, lactophenin, salophen, or phenocoll hydro- chlorate, was boiled with 10 C.C. of water (salophen being the only one insoluble), the liqilid cooled quickly and filtered through cotton. To 2-3 C.C. of the filtrate an equal volume of a 5 per cent. solution of potassium or sodium hydrate was added, with some crystals of potassium permanganate, until a violet colour remained after boiling.Two or three drops of a mixture of chloroform 10 c.c., alcohol 10 c.c., and ammonia solution 0.5 C.C. were then added and the liquid boiled, more of the chloroform mixture being added when the permanganate had not been completely reduced. After standing for a few moments the odour was noted and in doubtful cases compared with that yielded by a dilute acetanilide solution. By this test the author found that 1 per cent. of acetanilide could be readily detected in these allied compounds (cf: Hyde, ASALYST, xxi., 69). ... ... ... . . . . . . Salophen, C,H,(C7.H,0,,)NH(COCH:~) ... ... { liquid. I n testing exalgin the potassium permanganate was omitted. C. A. 31.292 THE ANALYST.The Alkaloids of the Kola-nut. Carles. ( A m . de Clzirnie Analyt., i. [18], 345-347.)-The accuracy of the estimation of caffeine and theobromine in Kola-nuts depends much on the state of division and dryness of the powdered nut, as well as on the solvent employed for the extraction. I t is essential that the nut should be powdered so fine as to pass through a No. 0 (120 mesh) silk sieve, and that it should contain about 25 to 30 per cent. of moisture, otherwise only part of the caffeine will be extracted by chloroform. In view of the sluggish action of this solvent on the alkaloids of the Kola-nut, it is preferable to add to it 20 per cent. of 93-94 per cent. alcohol, which facilitates solution and preserves the requisite degree of humidity. An admixture of linie assists in the liberation of the alkaloids which exist in combination with kolatannic acid as kolanine, and at the same time, by destroying the horny texture of the nut, facilitates lixiviation. In place of a Soshlet apparatus, an ordinary 100 C.C.flask may be used for the extraction, a straight or bent tube of 1 metre in length sufficing as condenser. Ten grarnmes of the sifted Kola-nut powder are inixed thoroughly with 1 gramme of calcium hydroxide and 20 granimes of 80 per cent. alcohol. After drying over the water-bath, until the weight of the mixture is reduced to 14 grammes, the powder is re- ground and heated in the 100 C.C. flask for an hour over the water-bath, with 35 C.C. of the alcohol-chloroform mixture, the solution and residue being separated by filtration, and the latter re-extracted three times in the same way, with respectively 35, 30, and 20 C.C.of the solvent mixture. The united extracts are evaporated to dryness, taken up with 10 C.C. of boiling water (containing 4-6 drops of 1 per cent. sulphuric acid), then by another 6 c.c., and finally by 5 c.c., of boiling water, filtered and dried at 100" C. until constant. The weight represents the caffeine plus theobroinine in the 10 grammes of powder taken. To determine the kolanine in the nut or nut extract, the caffeine may be extracted by means of cold water and the kolanine dissolved by 70 per cent. alcohol. On evapor- ating the alcoholic solution down to the consistency of an extract, and then taking this up with cold water, the kolanine will be left behind, and may be dried at a gentle heat until its weight is constant.The amount of alkaloids contained in the kolanine may be estimated by triturating 1 granime with an equal weight of calcium hydroxide and a little 70 per cent,. alcohol, adding 3 grainmes of chalk to increase the division of the substance, and, after drying down to 6 grammes, proceeding with the extraction by alcohol and chloroform. c. s. Estimation of Phosphoric Acid in Medicated Wines. F. Glaser and I(. Muhle. (Chem. Z o i t . , 1896, xx., 723.)-In working the processes that Fresenius has described for this purpose, whether the sugar contained in the wine has been removed by fermentation or not, it is not sufficient that the dried residue be carbonized, it must be ignited till it is perfectly white. Repeated extraction of the carbonaceous matter with strong nitric acid only recovers a portion of the phos- phoric acid, which would appear to be present in some insoluble modification. Although these methods are very accurate, provided the directions are followed exactly, yet they are tedious and require great care, while the author's process is sirnpler and gives equally satisfactory results.THE ANALYST. 293 100 C.C. of the wine are evaporated to a syrup in a 250 C.C. flask of Jena glass. After cooling, 25 C.C. of strong nitric acid are added, and the liquid is cautiously warmed till decomposition begins. When the evolution of gas ceases, 75 C.C. more acid are introduced, and the whole is evaporated over a naked flame until it is almost dry. The vessel is then cooled, 10 C.C. of strong sulphuric acid and a drop of mercury added, and the liquid is heated gently till it darkens in colour and the organic matter is destroyed. The mixture is again cooled, diluted to the mark, filtered, and after 100 C.C. of the filtrate (40 C.C. of wine) have been neutralized with ammonia, the phosphoric acid is thrown down with either molybdate or iiiagnesia mixture. Up to the time of precipitation the process takes only three hours. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8962100285

出版商:RSC    

年代:1896

数据来源: RSC

摘要:

THE ANALYST. 293 ORGAN IC ANALYSIS. Alcohol as a Source of Error in the Titration of Alkaloids. C. Caspari, Jr. ( A m c r . Jour. PlLum., 1896, lxviii., 473-481.)-Having observed during some analytical work that alcohol appeared to influence the colour produced by acids and alkalies with different indicators in the titration of alkaloidal residues, the author made experiments to determine whether alcohol really was the cause of the variation. He found that with the indicators tried-hzmatoxylin, cochineal, Brazil wood, methyl orange, lacmoid, and litmus-dilute alcohol and absolute alcohol as available in the market exerted a decided influence. With methyl orange it seeiuied to play the part of an alkali, a large amount of decinormal acid being required to produce394 THE ANALYST.the acid colour, whilst to the other indicators nientionecl it gave a strong acid reaction. The effect of alcohol on the results obt,ained in titratiug alkaloids was proved by experiments with morphine, cocaine, atropine, and strychnine. Solutions were prepared containing 0.5 gramme of alkaloid and 20 C.C. of decinornial acid in 100 c.c., and 10 C.C. of the soiutions used for each titration, the excess of acid being titrated with centinorrnal alkali. The percentages obtained were : Indicator. Hacniatoxylin . . . Cochineal ... Brazil Wood ... Methyl Orange ... Lacinoid.. . . . . Litmus ... ... Water 5c)iution. 98-58 98-48 98-32 98.55 98.91 98.41 IXlnte Alcohol Solution. 96.05 95-26 89.68 105.44 97.56 94-05 COCAINE. Water Solution. 97.26 96.35 95.95 97-20 97.44 96-35 1)ilute ~\lcOllol Solution.94.65 95-02 90.71 104.23 96.53 92.83 ATltOPI R E . Water Solution. 99.89 100.08 99-75 100.02 100.38 98-20 IXliite A lcoh 01 Solutioff. 96.82 97.33 94.62 106-58 97-95 91-49 Dilute Alcohol Solution. Sulution. 97-03 94-59 97.43 94-25 96.53 S9-11 97-19 103.54 98-03 97.19 92.11 84.03 In the case of methyl orange the dilute alcohol solution. required the addition of 1.5 C.C. of The addition of 5 C.C. of alcohol to 10 C.C. of the dilute alcohol solution increased the errors still further. Owing to the fact that quinine and cinchonine give an alkaline reaction with the indicators in acid solution, they cannot be estimated volunietrically in the same way as the other alkaloids, the results being altogether too high. Still, it was possible to prove that with these also the presence of alcohol influenced the result.h solution of quinine which, titrated in water, showed 117.18 per cent., gave 112.79 per cent. when titrated in a mixture of alcohol and water. The author concludes that while it is possible to accurately titrate alkaloids and alkaloidal residues in alcoholic solution, it is necessary to know the exact amount of alcohol present, and the relation of the centinormal alkali to the decinorinal acid, for the particular indicator used, in the presence of that amount of alcohol. I t is therefore advisable to make the titrations in aqueous solution. It is suggested that this behaviour of alcohol may be explained on the basis of Arrhenius's theory of electrolytic dissociation. According to Ostaaid, indicators depend for their value entirely upou dissociation, and although alcohols have a dis- sociating effect upon salts held in solution by then], it is less marked than in the case of water, and decreases with the increasing molecular weight of the alcohol.H,SO, before a satisfactory end reaction could be obtained. C. A. M. Estimation of Ethers in Alcohols. Barbet and Jandrier. (Rcz.. d c Chi??& dnnlyt., i. [19], 367.)-The aldehydes always present in industrial alcohols are resinified by the bases employed for the saponification of the ethers, and falsify theTHE ANALYST. 295 titration of the latter by neutralizing a certain amount of alkali. The extent of this error varies with the aldehyde present, and also with the initial degree of alkalinity employed in the test.For example, when the -:n normal potash amounts to 10 per cent. of the volunie of alcohol under examination, it is found t h i t one part of acetic aldehyde is equivalent to 0.18 of acetic ether, the coefficient for paraldehyde being 0.03, and for acrylic aldehyde 0.3'3; whereas when the ratio of potash is inci-eased to 30 per cent. the coefhieiit of the last-named aldehyde becomes 0-70. In view of the unreliability of these coefficients the authors sought to discover a reagent for saponifying the ethers, which should be without action on the aldehydes, and this they have found in calcium saccharate. A strong solution of this is pre- pared, employing Sparts sugar to 1 of lime, and the mixture allowed to stand for 24 hours. To apply the test the alcohol is reduced to 50 per cent.with water in order to prevent in 6ome measure the precipitation of the reagent. For industrial alcohols 10 per cent, by volume of the saccharate solution is employed. Saponification is effected by heating for two hours, after which the residual alkalinity of the liquid is titrated. The absence of resinificatioii and coloration renders the end reaction distinct. I t is then filtered and made up with sugar solution to decinormal strength. c. s. Differentiation of Aldehydes by means of Phenols, and vice vcrsd. Barbet and Jandrier. ( A m . dc Chimie ,I ILnZyt., i. [17], 325.)-The phenols, in presence of chemically pure sulphuric acid, give characteristic and extremely delicate colour reactions with aldehydes. To apply the test a few centi- grammes of (C.Y.) phenol crystals are placed in a tube and covered by about 2 C.C.of strong alcohol containing a trace of aldehyde. 1 C.C. of pure sulphuric acid is poured in gently down the side of the tube, and the resulting coloration at the plane of contact, and the change ensuing when the mixture is shaken up, are noted, In the case of a 0.001 per cent. solution of acrylic aldehyde a yellow tinge forms in the acid layer, and a violet in the supernatant alcohol. When shaken up the yellow disappears, leaving a fine heliotrope shade. Formic aldehyde may be distinguished from acrylic aldehyde by the negative results obtained with phenol, and by giving with gallic acid (which does not colour acrylic aldehyde) a yellow colour in the lower layer, rapidly changing to green by intermixture with the fine blue shade formed in the upper layer.When a 0.001 per cent. solution is in question the colour changes, on agitation, to heliotrope, passing into salmon red; with a 0.01 per cent. solution an intense dirty green coloration appears at the end of a few minutes. The subjoined table exhibits the colorations obtained by such of the phenol reagents as have so far been found to give definite results. /I-naphthol is extrernely delicate as a group reagent, and indicates the presence of as little as 0-00005 per cent. of acetic aldehyde; it also gives a characteristic red coloration with benzoic aldehyde, Hydroquinone and phloroglucinol also serve to detect the aldehydes en ~ZCLSSC, the former giving orange-yellow and the latter yellow colorations.For quanti- tative estimations 0.1 granime of hydroquinone, 2 C.C. of the alcohol, containing the (6'. ~ ~ N A L Y S T , sxi., 94.)COLOUR REACTIONS BETWEEN ALDEHYDES AND PHENOLS. Acetic Aldehyde. Acrylic Aldehyde. Pyromucic Aldehyde. Zonlrncrcial Formic Aldehgde. Yaleric Aldehyde, Benzoic Aldehyde, Acetal. Reagent. 1 iana At surface of contact. i-tibmi At wrface of contn,2t. rirtaa After n gitatio ti. 1 i m T i A t surface o i cont:\ct. 1 i n vim A t surfwe of contact. i v h v After agitation. 1 €3 vTi At surface of contact. 1 TTiUFii After agitation. 1 T U i i b At surface of CDD t RCt . 1 irm@ A t surface of contact 1 ivirr A t surface of contact. 1 in uu At surface of contact. 1 imii At surface of contact. Phenol ...orange yellow brown yellow brilliant yellow, fluores- cent yellow orenge yellow orange yellow, rose above yellow faint orange yellow yellow orange slightly orange yellow nil very faint yellow faint orange yellow yellow yellow, fluores- cent yellow orange yellow same, but weaker yellow faint orange yellow very slightly yellow very slightly yellow nil very faint yellow nil yellow, slightlj fluores. cent yellow, fluores- cent nil yellow faintly violet rose yellow very slightly rose nil nil nil almost nil fine violet , yellow below yellow b r own fine yellow, fluores- cent crimson, blue above orange yellow orange red, violet above POPPY red brown yellow, red brown yellow, blue above brown yellow slightly yellow yellow same, but less decided brown yellow, slightly fluores- cent yellow, fluores- cent faint violet red orange violet yellow yellow faint orange yellow slightly yellow, blue above violet almost nil very fine very faint Fellow helio- trope citron yellow yellow, slightly fluorea- cent rose brown yellow salnion rose yellow salnion blue helio- trope slightly yellow old-wine yellom yellow brown, turning to black violet red fine currant red as acid falls, green -brown afterwards greenish brown above brown yellow yellow, quickly turning blacE orange red, green above brown yellow, black orange yellow, greenish fluo- rescence brown yellow, black nil brown red, blue above brown yellow dark red, blue above carmine yellow aliiios t nil yellow, violet above greenish yellow brown yellow yellow yellow nil violet red light brown fugitive violet yellowisl brown yellow change able slightly bistre violet red violet red red brown violet iil iil riolet nil brown yellow, slightly fluor- escent orange yellow, fluorescent salmon rose orange yellow faint brown yellow brown yellow currant red, yellow yellow, c a r - mine above Jery slightly coloured, iiiilkj turbidity yellow, turning green, fine blue shade above Jery faint yellow faint orange yellow yellow yellow, no fluores cence yellow orange orange yellow yellow orange red yellow yellow yellow very slightlj yellow nil very fain yellow yellow orange red crimson, milky tur- bidity orange yellow orange orange yellow yellow orange red )range yellow, currant redabow )range yellow orange yellow nil rery faint yellow, red above nil brown yellow fine yellow, fluores- cent yell ow, with green marbling orange yellow orange yellow golden red yellow yellow pale yellow very nil slight 1 y yellow yellow a-Kaphthol .. . pXaphtho1 ... Hesorcinol . . . Hydroquinone Pyrogailol . . . Phloroglucinol Guaiacol ... Th)-iiiol . . . Pheiiyl Sa,lic. . . . Gallic Acid ... Camphor ...THE ANALYST. 297 aldehyde under examination, and 1 C.C. of sulphuric acid are employed, and the resulting shades of colour compared with solutions of Bismark brown standardized to the colours givcii by acetic aldehyde solutions of known strength in response to the same test. In the case of phloroglucin the standard colour solutions are prepared froni anilin yellow. Should the sulphuric acid contain nitrous impurities, accessory reactions will be produced, resorcin, for example, forming a deep blue colour at the surface of contact, surmounted by a fine red tinge, whilst the acid layer turns pale-green.I n applying the test to phenols ordinary phenol may be detected by acrolein (heliotrope). a-Naphthol by furfurol violet-red, P-naphthol by benzoic aldehyde, and so on. By employing the aldehydes in a 0.1 per cent. solution the colour reactions are readily differentiated. c. s. A Mothod for the Separation of Methylamines. M. Delepine. (??zlLI. Soc. Chinz., 1896, 701-704.)-The method depends on the fact that formaldehyde combines with mono- and di-inethglainines forming compounds with high boiling-points, but does not combine with tri-methylamine. With mono-methylamine it forms the conipound CH,:N.CH:, (B.P.3 66" C.), and with di-methylamiiie yields either CH,:LN(CH,),]2 or E O . CH,X(CH:,), both boiling at 80-85" C. Since tri-inethylaniine boils at 9" C. the fractions can be readily separated. To recover the bases froin the fractions the condensation products may either be saturated in aqueous solution with picric acid, when, on evaporation, the picrates of mono- or di-methylamine crystallize out, the former melting at 207" C. and the latter at 156" C. Or they iiiay be converted into hydrochlorides by the action of hydrochloric acid and alcohol, and evaporation of the solutions. Mono-methylamine hydrochloride, which crystallizes in plates, melts at 210"-220" C., whilst di-methylamine yields prisins (M.P. 171" C) which are much more soluble in water or alcohol thaii the lzydro- chlorides of the other two bases, Bismuth iodide may also bc used as a means of separating the base froin the fraction boiling at 166' C., inethylainine forming red hexagonal crystmals-(CH,N HI):; 2HiT,,-which, on boiling with potash, yield the base.Nessler's solution is a test for the purity of tri-methylamine, since with mono- inethylainine it gives a yellow insoluble precipitate, while the di-' and tri-methylamines yield white precipitates soluble in water. C. A. RI. Volumetric Estimation of Thiophen in Benzene. G. Denigzs. ( ~ ~ U ~ L . SOC. Chint., 1896, 1064, 1065.)--2 C.C. of the benzene are placed in a 60 C.C. flask with 30 C.C. of methyl alcohol free from acetone, and 10 C.C. of mercuric sulphate solution rapidly added. The latter is prepared by mixing red niercuric oxide 50 gramines, sulphuric acid 200 c.c., and water 1,000 C.C.The stoppered flask is left for about 20 minutes, after which the liquid is filtered froin the iiisoluble compound 'Hg - *\Hg. SC,H,, ",\Hg - O/ which is formed under these conditions. 21 C.C. of the filtrate ( = I C.C. of benzene) are placed in a litrc flask with 350 C.C. of water, 15 C.C. of ainmonia solution, 10 C.C.498 THE ANALYST. of potassium cyanide (equivalent to N/lO silver niwate) and 5 or G drops of a 20 per cent. solution of potassium iodide, and the whole well shaken. When perfectly clear, slight lieat being applied if necessary, decinorriial silver nitrate solution is added until there is a permanent turbidity. The amount of thiophen, z, in 1 litre of benzene can then be calculated by the foriiiula .x= ( n - 0.3 c.c.) x 2.H0, where n- the number of C.C.of silver nitrate solution ( C j . ANALYST, YX. 188, and this voiume, page 303). C. A. M. A New Unsaturated Fatty Acid. A. Rebsrt. (Bull. Soc. chiiii., 1896, xv., !)41-945.)--This acid, to which the author has given the name of isliiiic acid, is obtained by fractionally precipitating as barium salts the fatty acids obtained from I'Sano seed oil. I t crystallizes from ether in foliated crystals, and when purified by recrystalliza- tion melts at 41" C. I t is easily soluble in strong alcohol, ether, chloroform, benzene, acetone, inethyl alcohol and petroleum spirit, and is extremely sensitive to the action of air, rapidly absorbing oxygen and assuming a rose tint.Light also appears to play some part in the change. Its percentage compositiou is carbon 76-63 ; hydrogen 9.30 ; oxygen 14.07-results which correspond to the general formula C,LH2Jr.-s 0, ; I L in this case being equal to 14. The molecular weight as determined by Raoult's method approximated closely to 220, corresponding to the formula C,,H,o02. Attempts were made to add hydrogen by heating with hydriodic acid in a sealed tube, but only products of advanced-decomposition with traces of a liquid fatty acid were obtained. The acid absorbs two niolecules of iodine. The amiiioniuin salt is soluble in water and can be crystallized from that solvent, the crystals on exposure to air becoming first rose and then blue. The barium salt is a white powder and the lead salt an amorphous yellow powder, which dissolves in ether like the lead salts of the better known unsaturated fatty acids.C. A. M. Measurement of Rancidity of Fats other than Butter. A. Scala. (Stuz. Spin. rly. Itnl., xxviii., 733.)--Finding that the determination of the free acid in oils and fat was not an absolute measure of rancidity, the author proposes the use of the Reichert-Wollny method for this purpose ; Bornemann, Arata, and himself have previously called attention to the invariable presence of volatile acids in rancid fats. Lard, olive-oil, and stearin were exposed in flat basins, covered by large dishes, to the action of air and sunlight ; every 15 days a determination of the total volatile acids by the Reichert-Wollny method, and the free volatile acids by distillation with water (5 grainmes fat + 140 C.C. water ; 110 C.C.distilled) were determined. Fresh ... 15 days ... 30 1 , . . . 45 7 , ... 60 1 , 75 ,) . . . 90 7 , ... Laan. Total vol. Free vol. acids. acids. 0 0 0-6 0 0.8 0.2 2.5 1.5 4.0 1.6 5.2 2.3 7-8 4-6 Ormw-OIL. Total vol. Free vol. acids. acids. 0 0 0 2 0 1.0 0 1.5 0 2.8 0.4 3-2 0.8 3.3 1.1 STEARIN. Total vol. Free vol. acids. acids. 0 0 0.8 0 0 -9 0 1.s 0 -4 2.0 0% 9.3 0.8 2.5 1 -8THE ANALYST. 299 All results are expressed as C.C. of -& alkali for 5 grainines. H e proposes t o call a fat rancid which contains volatile acids, and suggest’s that a liniit of 2 C.C. be fixed, beyond which the fat should be considered no longer edible. IT. D. R. Examination of Linseed-Cake Oil. 13. A. van Ketsl and A.C. Aiitusch. (Xcit. n?igczr. C ’ / i m i ~ . , 1896, 581-5S3.)-The results obtained by Williams (ANALYST, ss.. 276) led the authors to examine the oil extracted by themselves from pure Iins& and froiii linseed-cake as sold in Holland. 111 every instance the Hiilul so1uti:in \YCL nllnwed to act for twenty-four lionrs 011 the fat before being tlitrutecl. Tix figuyes obtained with various oils extracted froni pure linseed confiri:ied those givm lo;, Williams, the mean iodine value being 1% With the oil froin linseed-cakc, however, tlie results were considerably lon (A; . only one saiiiple giving ’ztn iocline nuijiber of 184, whilst the others were 166, 167, 1 W. etc. None of the oi! eatracted fi-oiii tile linseed-cake was raiicid or solnbie to an: cxtent in acetic acid, so that alteration of the oil was I;ot the cauSe of the IOW figures.I n order to decide whether the preseiicc of foreign seeds lomexd the iouiiie ii~ii:iI?ei-, the oil was cxtractcd froin mixtures of pure linseed \i ith the foi.eign seeds usually iiiet with in linseed, and the iodine nuinloer detel-inined. Linseed, 101) per cent, . . . ... ... . . . ... IZa,pr: seed ( 7 1 ~ - a s s i c ~ ~ c(/ wimf r i s ) 100 per cent. Cameline seed (CumJlZin(i s[Ltira) 100 per cent. ... ... 90 per cent. linseed miti 10 por cent. caiiieline seed 85 ,, ,, 15 , l 1 , I ... SO 9 1 , l 80 ), 9 1 7 , ’ . . 90 10 ,, rape wed ... ... 35 9 , 7 9 11 2 , ), and 4 per cent. 90 J 1 1 ) 7 9 9 11 9 , 3 1 , ... ... ... ... ... 1 1 I ? 1uCiii:e SI . . . 1 :cr 1 0 1 . . . 1 4 t i ...179 ... 17-52 . . 170 . . . 17:j canielinc seed 17-1 ,, 9 , 176 The iodine nunib::rs of the mixtures were higher than those of the oils extracted froiii thc linseed-cake, and microscopical examination of the latter showed that. in every case less than 10 per cent. of foreign seeds were present. TTence the authors considered that the low iodine values were not due to this cause. Filially they tested tlie oil froiii tlie cakes with alcoholic ~ i l ~ e r nitrate solution (73rullk’s test), and with several obtained au unuiistaltahle reaction which they ascribed to the presence of cotton-seed oil. M7ith the oil from one of the cakes the reagent produwd a peculiar fatty niass xnlike anything obtained with p r c linseerl- oil or with oil froin the above-described mixtures. The “ o i l ” froiii another cake was stiff at the ordinary teiiiperature and had a wliite, horn-like appearance.The conclusion arrived a t was that;, in addition to the inicroscopical examination of linseed-cake the iodine number of the estracted fat should always be determined, and where this is low, and a t t8he same time the amount of foreign seeds sniall, special search should be niacle for cotton-seed oil and other oils. c. A. 8’1.300 THE ANALYST. The Composition of ‘‘ Driers.” M. Wager. (Zek anyyezii. Chem., 1896, 531- j36.)-The author considers that Amsel has based too much on incomplete theory in his recent communication on this subject (ANArJYST, xxi., 261). The formula? for the colophony acids are not yet settled, and the adoption of one or the other makes a difference of 2 per cent.in the amount of lead required by theory for the lead salt. Although Maly once found a stated percentage of abietic acid, etc., in a sample of colophony, a hundred samples might be examined without finding one of a precisely similar composition. Even in one and the same specimen the author has found considerable difference between the upper and lower portions in the proportion of the different acids and the degree of anhydride formation, as well as in the amount oi water and ethereal oil. Moreover, variations in the amount of metal may be pro- duced during the manufacture, and in the case of melted manganese rdsinate it is doubtful whether the metal is present as inanganous or manganic oxide, or as a mixture of both.I n precipitated ‘‘ driers ” the possibility of thp, formation of basic salts is to be taken into account. The requirements for a soluble ‘‘ drier ” in practice are that it must be completely soluble, and that the metal must be in combination and not partially suspended as oxide. The estimation of the total amount of metal is therefore no criterion of the value of a product, since the suspended matters in many commercial siccatives (PbO, Mn,O ~, CaO, etc.) are not only valueless, but are distinctly harmful to the varnish. The best solvents for testing a preparation are ether and (in the case of lead resinate) chloroform, the solubility of a siccative in these corresponding with its solubility in linseed-oilJ with the difference that no heat is required.Therefore when a product is insoluble in cold ether or chloroform, it is also insoluble in moderately hot linseed-oil, and is worthless. Only lead and manganese are used for ‘( driers,” although zinc, calciuiii and barium resinates are mixed with copal in commerce, but if no lead or manganese be present the preparatians are of no use in varnish manufacture. The higher the amount of soluble lead or manganese, in the absence of insoluble matter, in a siccative, the less is required to be added to a linseed-oil. Lead siccatives are hardly used, the ordinary preparations being manganese resinate, lead and manganese resinate, manganese holeate* and lead and manganese linoleate. As regards their composition, the author, froiii the examination of hundreds of samples, finds that the soluble manganese in fused resinates seldom exceeds 3.2 per cent.(manganic oxide), whilst in precipitated resinates it is seldom over 6, or in exceptional cases 7, per cent. (manganous oxide). Good preparations of fused manganese linoleate have from 9 LO 9.5 per cent. of soluble manganese, though the author has found as much as 11 per cent., an amount which points either to a deep- seated change during the heating or to the formation of basic salts. Precipitated manganese linoleate does not occur in commerce. The preparations most used are the fused lead-manganese resinates, and in these the most suitable relation of lead to manganese appears to be as 5 : 1. The products of one of the best-known firms are fairly concordant in this respect, having 8 to 9 per cent.of soluble lead, with 1.5 to 2 per cent. of soluble manganese. Lead-manganese linoleate, which is not much used, comes into the market with very varying composition. Higher percentages of soluble -X Linoleate here means the metallic compound of the mixed linseed-oil acids.THE ANALYST. 301 metals than the above-mentioned are invariably accompanied by insoluble metallic compounds, which are, in fact, only completely absent in very few preparations. The fact that many samples contain a considerable quantity of imoluble matter (Mn,O:,, MnCO:,, etc.) does not prevent free resin and linseed-oil being present, and most of the fused preparations in the market contain both. Falsification of resinates with resin is practically non-existent, notwithstanding Amsel's supposition, nor could rriuch profit be derived from the practice ; but the case is otherwise with linseed-oil siccatives, where the addition of resin would pay, although the author has nct yet met with it.With regard to the use of soluble siccatives, the quantities required for the preparation of a good varnish are: melted manganese resinate 2 to 3 per cent. ; melted lead-manganese resinate 2 to 3 per cent.; melted iiianganese linoleate 1 per cent. ; precipitated manganese resinate 1 to 13 per cent. The siccative is either put directly into the linseed-oil heated to about 120" C. (not higher than 150"), or preferably 1 part of the siccative is dissolved in 2 parts of linseed-oil at 120°, and the mixture stirred into the main bulk. The oil can be oxidized either before or after the addition of the '( drier." For clear varnish lead-manganese resinate is used, and where all separation is to be avoided, iiielted manganese resinate.For the preparation of turpentine-oil siccatives melted manganese resinate, manganese linoleate, and lead - manganese linoleate are employed dissolved in the turpentine-oil in the proportion of 1 : 2 or 2 : 3. In the analytical examination of soluble siccatives the organic matter is first burnt off and the lead and manganese in the ash determined. I t is useless to weigh the total ash, since resiiiates often contain sand. If, after the removal of lead, calciuni be present to any extent, the manganese and calcium are deteriiiined together in neutral solution as carbonates, the manganese titrated and the calcium found by difference.The insoluble lead and manganese are then deterinined Ly dissolviug a fresh portion of the siccative in ether or chloroform, filtering, washing, igniting, etc. The soluble manganese is determined by the difference between this result and that) of the total manganese, and the result may be controlled by determining the soluble manganese in an aliquot part of the filtrate. The soluble lead must be determined by difference, since the chloroform cannot be completely evaporated from the resinate solution, traces remaining except at red heat, when iiiost of the lead volatilizes with it as lead chloride. c:. A, x. The Estimation of Phenol i n Soaps and Disinfectants. H. Preseaius and C. J. S. Makin. (%(!it. a i i c t l .L'/iewi., 1896, xxxk., 325-334.)-The estimation of phenol in aqueous solutions, or in crude carbolic acid, presents no special diflficulty, but the case is often otherwise when the phenol is inixed with soap. Of the methods hitherto employed, the authors prefer that of Low, in which the fatty acids are liberated and the phenol determined in the filtl*ats either gravimetrically, as tri-bromo-phenol, or volumetrically by lioppeschaar's process (Zeit. n m l . Clreiiz., xv., 233). The method now described is based on the fact that phenol is volatile with steam, and can be determined in the distillate, preferably by Tilth's modification of Koppeschaar's process (Zeit. anal. Ckcm., xxv., 160).:302 The solutions rcqnircd are : (1 ) Sodium tliiosulphate containing 9.763 qraiiiines per litre.Tiiis is standardized on iodine, and from the result the equivalent of broininf> calculated. ( 9 ) A bromine solution containing 2-040 grnmmes of sodium broniate and 6.959 grttmines of sodinin bromide p'r litre. (3) Clear starch solution. (4) -1 solution of potassium iodide containing 1.25 grammes, which is freshly prepared for each determination. The bromine solutior, is standardized on tlie thiosulphate solution by shaking 25 C.C. of the former with 5 C.C. of hydrochloric acid for a few minutes in a stoppered flask, adding 1-2.j grnmnies of potassium iodide, ant1 titratmirig wit 11 the tliiosulphate. The ;imount of bromine contained i n 1 C.C. is thus determined. In determining the quantity of phenol i n a solution an excess of the bromine solution is added with 5 C.C. of hydrochloric acid, and the stoppered flask shaken €or 30 iiiinutes. A freshly-prepared solution of potassium iodide (1.25 gratnmes in 30 c.c ) is then added, and after standing for 12 hours the liberated iodine titrated with stundard thiosulpliate. The amount of hroniine used is thus obtained, and from that the equivalent qiiantity of phenol by the proportion 6Br : C,,Hr,OH A solution of phenol of kiiown strength was titrated directly by this method, and after distillation cither over a Bunsen flame or by means of a rapid current of steam : concortl~tnt results were obtained i n each case. Next, mixtures of the phenol solutioii and soap were prepared, the fatty acid separated froin the latter by means of dilute snlyliuric acid and tlie phenol distilled in a current of steani. In this case the results were about 1 per cent. too high, which was attributed to the action of the broiiiine on traces of fatty acids in the distillate. I3lauk experiments were therefore made with soap containing no phenol under ex Actly similar conditions, and the results beiiig deducted froiii the previous figures, gave the ainount of phenol required by theory. Several carbolic soaps were tested in this way, and in one there was found ( ( I ) 1.503, ( h ) 1.665 per cent'. ; and in another ( ( I ) 3.38, ( b ) 3 5 1 per cent. of phenol. 111 a sample of phenol soap which, according to the preparation formula, contained 1.738 per cent. of phenol, the analysis gave 1.633 per cent. 1 n exmiining disiufecting powders, about 0-5 granime is taken, water added, with about 50 C.C. of concentrated hydrochloric acid, and the phenol distilled over by means of a wipitl current of steaiu, and titrsted in the distillate as described above. C. A. hf. (479.70 : 94).

ISSN:0003-2654    

DOI:10.1039/AN896210293b

出版商:RSC    

年代:1896

数据来源: RSC

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:302 INORGANIC ANALYSIS. The Determination of Sulphurie Acid, or of Barium. J. Edmunda. (CIlici~L. News, lxxiv., 187.)-The author proposes to estiiiiate sulpliuric acid by precipitation with an excess of barium nitrate, the residual barium being precipit'ated by excess of neutral potassiuiii chroiuate, and the residual chroinate by silver nitrate in excess, the mixture being ell shaken after each addition. It is the I filtered, and an aliquot part of the filtrate titrated for its residual silver nitrate, potassiuni chromate being uszd as indicator. The tot,al of the residual silver nitrate, deducted froin the silver nitrate originally employed, gives the equivalent of thp_ snlphnric acid.THE ANALYST. 303 Each precipitate is thrown down in the presence of an ample excess of precipi- tant, and the minute quantity of silver chromate whichlwould remain in solution in a filtrate charged with certain salts is compensated for by using the potassium chromate indicator in the titration of the residual silver.Haloid radicles and other precipitants of silver are best estimated by a preliminary titration and allowed for in the final titration. A preliminary volume of the solution is shaken with i% silver nitrate in excess, the precipitate filtered off, and the residual silver titrated by means of thiocyanate with ferric sulphate. I n determining barium the solution is shaken with an excess of neutral sulphate, the amount of the excess being afterwards ascertained by the process above described. Freedom from other substances, such as lead or strontium, which precipitate sulphuric acid, is presupposed.C. A. M. General Method for the Estimation of Mercury. G . Deniges. (BUZZ. SOC. Chim., 1896, 862-871.)-The method is based on the facts that when an excess of potassium cyanide is added to the solution of a mercuric salt, the compound Hg(CN),2KCN is formed, and that on adding ammonia and running in silver nitrate solution, this donble salt is decomposed : A solution of potassium iodide is used as indicator, and the completion of the reaction is shown by a permanent opalescence due to silver iodide. The solutions required are deciuorrnal silver nitrate, an equivalent solution of potassium cyanide, and a 20 per cent. solution of potassium iodide. I n making an estimation, 10 C.C. of ammonium hydrate are added to the solution of the mercuric salt, then an excess of potassium cyanide solution, and after the addition of a few drops of potassiutn iodide, the silver nitrate run in until the opalescence remains permanent.The diflference between the number of C.C. of potassium cyanide taken, and the number of C.C. of silver nitrate used, gives the amount a of decinormal silver nitrate corresponding to the mercury in the solution. I n practice the reaction is never completed according to the equation, a small quantity of the double cyanide remaining undecomposed, and for very accurate work a correction must be made. This may be calculated by the following rules : (1) When a is between 0 and 5.5, the true value, x, =a x 0.96. (2) When cc lies between 5.5 and 9.5, x= (a x 1.04) - 0.45. The amount of mercury is obtained by multiplying IC by 0.020 grammes. It is stated that the estimation may be made in the presence of strong mineral acids, that alkalies do not affect it, and that it is capable of very general application. Hg(CN),SKCN + AgNO, = Hg(CN), + AgCN.KCN + KNO,. C. 8. M.

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DOI:10.1039/AN8962100302

出版商:RSC    

年代:1896

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304 THE ANALYST. APPARATUS. An Improved Hydrometer. T. Lohnstein. (Chem. Zeit., 1896, xx., 559.)- This instrument is essentially a form of the old Fahrenheit hydrometer, so modified as to obviate the disturbing influence of capillarity. The principle is as follows : If a glass tube, loaded in the usual manner so as to float vertically, is cut off at the level of the liquid in which it is iniinersed at right angles to its major axis, the effect of some considerable addition to its weight is simply to alter the meniscus from concave to convex without causing the instru- ment to sink. If the instrument does not float quite vertically, the true position will be when the con- cavity of the meniscus on the one side is equalled by the convexity on the other, while the two points midway are absolutely at the level of the liquid.The general form of the apparatus is shown in the figure. G is the hydrometer bulb, of such a size as to displace 50 C.C. of water at 15” C. h is a glass rod ground and cemented into the aperture of G, while at the other end it slips loosely into the tube H of the brass scalepan B-S. t and 771. are parts of an ordinary releasing gear to prevent overloading. The machine is adjusted so that with the pan in position and empty G assumes its “Archimedean position” (as shown in the enlarged plan) in a liquid having the specific gravity 0.7 at 15” C. Seventeen bras3 weights are provided corresponding to increases of density (over 0.7) of 0.5, 0.3, 0.2, 0.1, 0.05, . . . 0.0001, so that by adding together the values of all the weights required to make G float normally, the specific gravity Of the liquid under examination is given directly. When only small variations of density are expected, the apparatus m y be simplified by removing the stirrup-pan and substituting the flat table of Fahrenheit ; or the vessel may be constructed in the form of an inverted cone, loaded at the apex to give it a still greater range, with a table on the top for small weights, and two or three riders equal to 0.3, 0-6, and 0.9 respectJively. The author claims to get figures exact to the fifth place of decimals if proper care as to temperature, etc., be taken. 3’. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8962100304

出版商:RSC    

年代:1896

数据来源: RSC

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THE ANALYST. 305 L E G A L . IMPORTANT DECISION WITH REFERENCE TO MILK CERTIFICATES. QUEEN’S BENCH DIVISION. (Bqfow MR. JUSTICE GRAXTIIAJI aid MR. JUSTICE KENNEDY.) (Repiizted .fi.ort$ tlie ‘‘ Yirtaes ” of October 29, 1896.) 1:RIDCE V. KOIYARD. This was a special case stated by two justices for Middlesex in regard to a milk adulteration case, and raised a point as to the snfficiency of the analyst’s certificate. Mr. EARLE appeared on behalf of the appellant, the Public Analyst, and said the case arose in consequence of the decision of the Divisional Court i n Foduize v. Huizson (189G, 1 Q.B., 203), when a certificate was held bad which stated only that the sample “contained the per- centage of foreign ingredients as under 5 per cent. of added water.” The certificate in this case was in the following words : “ I, the undersigned, Public Analyst for the county of Middlesex, do hereby certify that I received on March 26, 1896, a sample of new milk (E.M.159) for analysis (which then weighed 6 oz.), and have analysed the same, and declare the result of my analysis to be as follows : I am of opinion that i t contains the parts as under-milk, !)-I per cent. ; added water, 6 per cent. This opinion is based on the fact that the sample contained 7.97 per cent. solids-not-fat, whereas genuine milk contains not less than 8.5 per cent. solids-not-fat. The sample had undergone no change which would interfere with the analysis.” A t the hearing of an information on April 24 against the seller of the sample of milk, this certificate was tendered by the appellant, but it was objected, on behalf of the reBpondent, that it was inadmissible on the ground that it did not state specifically, as the result of the analysis, the parts contained i n the sample analysed.The hearing was then adjourned, and on the rehearing the appellant contended that the certificate was valid and sufficient, and also tendered the oral evidence of the Public Analyst, who was present, as to the constituent parts of the Ram+, and as t o the inutility of stating specifically the amount of the water and other con- stituent parts of the milk, having regard to the usual and scientific method of analysis, and a8 t o the proper manner of analysiug milk. The respondent objected, on the ground that proceedings for the recovery of penalties can only be maintained when a Certificate in com- pliance with the statute has been given, and that the analyst could not by oral evidence supplement his certificate. The justices, being of opinion that the certificate was insufficient, as not setting out specific quantities of all the constituent parts of the sample, and also that the proceedings could not be maintained in the absence of a certificate setting out the said quantities specifically, declined t o hear the oral evidence, and dismissed the information.Mr. EARLE contended that the certificate was sufficient, as it gave the analyst’s reasons for saying that a certain proportion of water had been added. The justices bad the materials afforded them t o enable them to say whether they adopted the conclusion arrived a t by the analyst, and in this respect there was a difference from the certificate in I7o~tu7zc v.Hu7zson. It was proved that there was a certain deficiency of solids in the sample. Therefore a certain quantity of foreign ingredient must have been added ; and inasmuch as the sample had under- gone no change, the foreign ingredient must be water. The analyst had made an analysis on a different principle t o that contemplated in the case referred to, and he considered that i t would serve no useful purpose t o state the total amount of water in the milk, both natural and added. On the second point-namely, the refusal of the justices t o hear evidence-he admitted that if the certificate was not in accordance with the Act they were justified i n refusing evidence.The point was, therefore, the same as to that part of the case as in the other. The COURT upheld the validity of the analysis (certificate).306 THE ANALYST. Mr. JUSTIC'K GHANTJIAJI said the justices were wrong in rejecting the certificate. The analyst here had done enough in setting nut the amouiit of solid substance which he found in the sample, and basing his decision thereon. It was hopeless to go into the question of how much water there was in the milk altogether. I n some cases rich milk which had been adulterated with added water contained less water than perfectly pure milk of a poor class. The analyst had stated the principle on which he came t o his conclusion. It was simply a rule of three sum, and, i n fact, he had rather understated mztters when he gave 6 per cent. as the iimoun t of added water. Mr. JUSTICE: KENNKDY, having been one of the Judges in Fortuiie v. H ~ t i ~ o i z , desired to add that he was still entirely of opinion that a similar Certificate to the one in that case would be bad It merely contained a statement of opinion that a certain percentage of water had been added, and it did not give the ground for that opinion so as t o enable the justices or the party accus?d to test the accuracy of it. He thought it fairer that the proportionate parts should be set out, and as water was an ingredient in all milk, more was required thal: a state- ment that there was water added. Here the analyst not only stated tLat ti per cent. of water had been added, but he gave scientific reasons for that statement. That made the difference between the certificate i n this case and in the other. H e concurred in thinking that this cer- tificate was sufficient. (For report of the rase of ForftinP v. Haizsoii see tbe AS~LYST, this volume, 1). 53.)

ISSN:0003-2654    

DOI:10.1039/AN8962100305

出版商:RSC    

年代:1896

数据来源: RSC

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306 THE ANALYST. R E V I E W S . -4LIMENTOS Y BEHIDAS, INVESTIGACION DE SUS ALTEHACIOSEY Y FALSIFICACIONES, por el DIL C~SAH. CHICOTE. THIS is a goodly octavo of 734;pages, from the pen of the principal of the municipal laboratory at San Sebastian, and probably forms a good outline of what was known in Spain at the end of 1893 on the subject of the adulteration of food and drink. I t is modelled very niuch on the French style, and ignores all direct reference to the German, English and American literature on adulteration. Indeed, in the three appended pages of bibliography only one English work, Sutton’s “ Manual of Volu- metric Analysis,” is directly quoted, and this in the French translation. French, Portuguese and Italian works are freely quoted. Subject to these reservations, the iuformation is copious, and, as might be expected, wines are treated of in an elaborate nianner.The illustrations-mostly French-are excellent, and we congratulate our Spanish confrkre on his creditable production. T. S. T H E BOOK O F THE DAIEY, TBANSLATED FROM THE GERMAN OF PROFESSOR FLEISCH- 31.4~. BY C. 91. AIKMAX AXD R. P. WRIGHT. (London, 1896: Blackie and Son.) xsiv+344. Price 10s. 6d. “The Book of the Dairy” difl’ers from most works on milk, in that it partakes inore of the nature of a monograph than of a coiiipilation; though the author has no6 hesitated to make judicious use of the researches of others, the groundwork of the book is solid fact, the result of his laborious investigations. To say that the author is Fleischniann is very nearly a, sufficient critique ; yet the translation has faults.Of what practical use is it to the British dairy farmer to know the profit yielded by dif’ferent treatments of milk in pfennige per kilo? Why should dairy utensils inTHE ANALYST. 307 use in Germany only be mentioped in the text, while the illustrations refer to those of British make, which are otherwise ignored ? Why are centigrade degrees, kilos, and litres used in a book designed for men who think and work in Fahrenheit degrees, pounds, and gallons? Had the translators but seen their way to Anglicize to a greater extent, the book would have been really useful, instead of merely in- s t ruc t ive . The chemical portion of the book is clearly and concisely written, and ou the whole very exact, but is distinctly behind the times; this is perhaps due to the delay of translation, the work appearing simultaneously with that of a second and enlarged German edition.The analytical part is somewhat weak ; for example the Adams’ method is given second place to the process of extraction of fat with sand ; the essential point of this beautiful method is missed, when it is directed to place as much as 8 to 10 gramines of milk on a coil, The method for total solids, too, is distinctly inferior to that used in England. I t is greatly to be regretted that analyses have been ‘‘ cooked ” to make t,hem add up to 100.00 ; for instance, on page 269, an analysis of I ‘ curd-whey ” duly adds up to this figure, and includes 4-87 per cent. milk-sugar; in the original analysis, which added up to 99.506, the milk-sugar was returned as 4.377 per cent.I t is surely time that the analyses of condensed milk on pp. 284,285, which date from 1868-1878, were replaced by figures showing the composition of the modern product. The same applies to Gerber’s analyses of comniercial milk-sugar (made in 1878), which show only 92 and HT, per cent. of milk-sugar ; to-day 99.7 per cent. is a more usual figure. One of Dr. Gerber’s analyses is remarkable for adding up to 99-99 per cent. Among errors which are misleading, the apparent contradiction between the statement (page 16) that the specific gra,vity of perfectly fresh milk is Iiiglici. than that of milk after standing, and that on page G 8 that it is lowe?., and the statement that the lacto-butyrometer cannot be used for niilk containing 11207-e than 1.339 per cent.fat (instead of less), may be mentioned ; also the use of the terms “ absorptive capacity for heat,” ‘‘ latent heat” (page 13), and specific heat” (page 117), as identical in meaning. We find in the directions that after filtering “ in the presence of a weak diluted atmosphere” a glass tube is to be stretched and bent on a holder downwards “ (page 85), and the confusion between of the terms “cheese-milk ” (Kiise milch) ana There is a quite unintelligible passage on page 28, referring to the amount of phosphoric acid derived from the casein, where the translators do not seem to have grasped the author’s meaning. The bulk of the information is very correct ; figures that are ustlally misstated, p.g., the density of solid milk-sugar 1.545 (page 95), are here correctly given.Despite the fact that much of the information is out of date, and much essentially Teutonic, this work can be highly reconimended to public analysts’ and consulting chemists as affording an insight in to dairy practice. whey ” (molken) (page 2 0 ) does not reflect credit on the translators. H. D. 1%.308 THE ANALYST. A SYSTEMATIC HANDHOOK OF VOLUMET~~IC ANALYSIS. Seventh edition, enlarged and improved. By & ” l t a ~ u ~ s ~ U T T O N , F.1. c., London, J. and A. Churchill. F.C.S. All analysts will welcome the appearance of the new edition of Mr. Sutton’s well-known work, which brings the subject with which his name has been so long associated well up to date. Among the sections which are either entirely new, or have been altered and added to, are those on the Calibration of Instruments, the Kjeldahl Process, Boric Acid, Hydrofluoric Acid and Fluorides, Cyanogen and Cyanides, Phosphoric Acid, Sugar, Tannin, Zinc, [Jrine, etc.In his preface the author states that, as respects the volumetric method as applied to any organic substances, and the action of modern indicators in such work, nothing has been attempted, mainly because the subject comes specially within the scope of Allen’s L‘ Commercial Organic ilualysis.” Mr. Sutton states that he has availed himself in some instances ‘‘ of the excellent abstracts of original papers now being published in THE ANALYST, which reflect great credit on the present manage- ment in this department.” In the case of a work which has been so long known and highly appreciated as that under review, and which has reached its seventh edition, there is little room for criticism.The arrangeineut of the subject-matter is familiar to every chemist, and at worst any particular article wanted can be found by the aid of the index. Throughout, one is struck with the author’s remarkable powers of assimilation, pro- cesses of all kinds being described in their proper place, and in Mr. Sutton’s well- known terse and lucid style. The article on Cyanides cont,ains the most recent processes for exarnining the cyanide liquors of gold works. Amongst collaborators, the author makes mention of, and expresses his thanks to, Mr. W. B. Giles for an original article on the Estimation of Hydrofluoric Acid, and for the benefit of his long practical experience in the examination of sulphur compounds aud phosphoric acid; to Mr. J. W. Westmoreland for great services rendered in the articles on Copper, Iron, and Manganese ; aqd to Dr. James Edmunds for suggestions on Urinary Aualysis which the author believes to be of considerable practical value. The section on Water Analysis has been added to in various respects, and is now one of the most complete treatises on the subject in the language; while in the chapter on the Volumetric Analysis of Gases the author has placed on record a number of recent improvements. The whole work now covers 487 closely-printed pages, and is a monument of carefully-collated information. I ‘ Sutton ” has long been one of the most constant companions of aualytical chemists of every class, and the new edition fully main- tains the reputation of the author for excellence of work in every respect. The nomenclature adopted is mainly the same as in previous editions. -4. H. A.

ISSN:0003-2654    

DOI:10.1039/AN8962100306

出版商:RSC    

年代:1896

数据来源: RSC