then dipped into very dilute ammonia, become dirty green if the wine be pure, but blue if indigo be present. Indigo being often used to mask the too bright colours of cochineal and fuchsine, these should always be sought for after the removal of the indigo by clarification with albumen. Indigo very rapidly separates from wines, and it may frequently be found in the lees, even when the wine itself gives no indication of its presence. Except in such cases as indigo and cochineal, it is only upon a series of concordant reactions that the presence of an artificial colouring-matter should be affirmed. § 285. Mineral Substances, or Ash.-The ash of a great many wines, and especially of sherries, imported into this country, consists nearly entirely of sulphates.* This is due either to sulphuring or plastering. It is found absolutely necessary to charge many wines slightly with sulphurous acid, some of which becomes sulphuric acid; and in such a case the chlorides and carbonic acids are diminished in the ash, and the sulphuric increased, but the total weight of the ash itself is not materially increased. On the other hand, plastering (by which is meant the addition of plaster of Paris to the grapes before they are crushed) has the effect, by its reaction on cream of tartar, of producing a soluble sulphate of potassium, which may very materially increase the ash of the wine.† *The sulphuric acid in sherries ranges from 1.5 to 8 grms. per litre (equal to from 19.0 to 93 8 grains per bottle of gallon). + A plastered wine contains more potash than one not plastered, for in the latter there is a deposition and separation of the hydro-potassic tartrate, but in plastered wines from double decomposition calcium tartrate is formed and deposited, whilst potassic sulphate passes into solution. According to Hilger, a plastered wine always contains more than '06 per cent., SO3, and shows a notable increase of the ash constituents. The general view of the reaction which occurs on the addition of calcic sulphate is that some tartaric acid is also set free according to the following equation : 2C4H KOε+SO4Ca=C4H4CaO6+SO4K2+C4H6O6· This free acid again acts on the potassic sulphate, forming SO4HK and CH KO. R. Kayser, on the other hand, considers that free phosphoric acid is formed-SO4Ca + C4H5K06=SO1HK+C4H4CâО6, and then SO HK+P04H2K=SO4K2+P04Hз, and that it is this free phosphoric acid which gives the lively tint to red wines. Plastering clears a wine rapidly, because the calcic tartrate quickly separates. The main chemical changes, therefore, which can be traced are, briefly, a decrease in the tartaric acid and an increase in potash and sulphates. The standard in use in the Paris Municipal Laboratory is 2 grins. per litre of potassic sulphate; should a wine contain more than this quantity, it is considered plastered. The maximum amount of potassic sulphate found by M. Marty in genuine wine was 6 grm. per litre. A preliminary examination of the wine is effected as follows:-A solution of 5-608 grms. of baric chloride and 100 cc. of HCl is made up to a litre with water. Two Under absolutely normal conditions, the ash consists of carbonate, sulphate, phosphate, chloride of potassium, chloride of sodium, phosphate and carbonate of calcium, with very small quantities of magnesia, iron, silica, and frequently lithium and manganese. The ash from a litre of wine examined by Boussingault contained Potash,* Phosphoric Acid, Sulphuric Acid, Chlorine, Carbonic Acid, Sand and Silica, Grms. 0.842 0.092 0.172 0.412 0.096 a trace 0.250 0.006 1.870 With regard to the analysis of the ash, &c., see p. 117, et seq. § 286. Detection of Fluoborates and Fluosilicates.-Alkaline fluoborates and sometimes alkaline fluosilicates are used as antiseptics in the manufacture of wine. Their detection is as follows:-100 cc. of wine are treated with an excess of calcium hydrate and evaporated to dryness and ignited. Should fluoborate have been used the borate of lime is soluble in acetic acid, while both fluoride and silicate of lime are insoluble in acetic acid. Therefore, after ignition the ash is treated with acetic acid and filtered. On evaporating the acetic acid solution to dryness the residue is tested for boric acid as described on p. 312. Silicates are determined in the insoluble portion of the ash remaining on the filter, and fluorides are detected by heating the ash so as to render it anhydrous, and, after mixing with a little sand, transferring it to a test-tube, then adding sufficient strong sulphuric acid to form a paste and closing the mouth of the testtube with a cork carrying a small U-tube, a single drop of water having been put in the bend. On now heating the test-tube, fluoride of silicon is evolved; but immediately decomposes on passing through the drop of water; hence there is a characteristic deposit of gelatinous silica in the U-tube. If, therefore, by these processes silicon and fluorine are detected, the amount of silica being in excess of what is usual in the ash, a silicofluoride has been added; or, if fluorine and boracic acid have been found, this denotes the presence of a fluoborate. tubes are charged, each with 20 cc. of wine, and to the one is added 5 cc. and to the other 10 cc. of the barium of chloride solution. If, after the precipitate has subsided, the clear liquid from the 5 cc. tube gives no precipitate, the wine is not plastered; or, if it gives a precipitate, whilst the second tube gives no precipitate, the plastering is beneath the standard; but if the second tube gives a precipitate, the wine is plastered, and the usual methods of estimation must be adopted. The rule is that nearly half the ash of a natural wine consists of K,O in combination. BIBLIOGRAPHY. BATILLIAT.-"Traité surs les vins de la France." BERTHELOT et DE FLEURIEN.-Journ. Chim. Méd., 1864, t. x., p. 92. CHANCEL, G.-Comptes Rendus, lxxxiv. 348-351. CHEVALLIER.-Ann. d'Hyg., 1856, t. v.; 1857, t. vij.; 1870, t. xxxiii. ; 1876, t. ij., &c. DUCLEAUX, E.-Ann. Chim. Phys. [5], ij., pp. 233-289. DUPRÉ, A.-Proceedings of Soc. of Analysts, i., 1876; Analyst, i., 1877, 26, 186. FERRIÈRE, SANGLE.-Art. "Vin" in Ch. Girard and A. Dupré's “Analyse des Matières alimentaires." Paris, 1894. GAUTIER.-Bull. Soc. Chim. [2], xxv. GRIFFIN, J. J.-"The Chemical Testing of Wines and Spirits." London, 1872. HAGER.-Pharm. Central Halle, 1872, No. 27. HASSALL."Food and Air," 1874. JACQUEMIN. Bull. Soc. Chim. [2], xxvj., 68-71; Analyst, i., 1877, 148. LASSAIGNE. Journ. Pharm. et Chim., 4e sér., 1870, t. xi.; Ann. d'Hyg. [2], 1831. MAUMENÉ, E. J.-"Traité théorique et pratique du travail des vins." 2e éd., Paris, 1874. MONAVON, MARIUS.--"La coloration artificielle des vins." Paris, 1890. ODEPH, ALP.--Journ. Chim. Méd., 4e sér., 1860, t. vj. NEUBAUER, C.-"Ueber die Chemie des Weines." Wiesbaden, 1879. PASTEUR. "Nouvelles observations sur la conservation des vins." Svo, Paris, 1868. POGGIALE.-Journ. Pharm. et Chim. [3], 1859, t. xxxvj., p. 164. SCHMIDT, CONRAD.-" Die Weine des Herzoglich Nassauischer Cabinetskeller." Berlin, 1893. THUDICHUM, J. L. W., and DUPRÉ, A.-"A Treatise on the Origin, Nature, and Varieties of Wine." Svo, London, 1872. VOGEL, H. W.-Deut. Chem. Ges. Ber., ix., 1900-1911. PART VII. VINEGAR. $287. Constituents of Commercial Vinegar.-Vinegar is a liquid resulting from the acetous fermentation of a vegetable infusion or decoction; it contains acetic acid, acetic ether, alcohol, sugar, gum, extractive matter, alkaline acetates, and tartrates, a variable amount of salts (depending on the substances from which it has been produced), and legally not more than 1.85 parts by weight of pure sulphuric acid per 1,000 of vinegar. Varieties of Vinegar.-The chief varieties of vinegar are as follows: : (1.) great majority of commercial vinegars in this country are derived from the acetous fermentation of a wort, made from mixtures of malt and barley. Malt-vinegar is of a decided brown colour, in specific gravity varying from 1.017 to 1019; it is of various degrees of strength, the manufacturers distinguishing different kinds as Nos. 18, 20, 22, and 24, respectively, the last being the strongest, and containing about 4.6 per cent. of acetic acid. That made by one of the largest firms in this country will be found to contain from 1 to 16 per cent. of combined sulphuric acid, and from 04 to 08 per cent. of chlorine, as chlorides. (2.) Wine- Vinegar is the chief vinegar in Continental commerce. It is prepared from grape-juice and inferior new wines; that made from white wine is most esteemed. The wine-vinegars vary in colour from pale yellow to red; they have nearly always an alcoholic odour; specific gravity from 1014 to 1022. A litre of Orleans vinegar (according to Chevallier's* analyses of actual samples) saturates from 6 to 7 grms. of dry carbonate of soda. The extract from pure wine-vinegar varies from 1:38 to 3.2 per cent., the average being 1.93 per cent., and usually contains 25 grm. of tartrate of potash (see Table XLVa.). Vinegars of limited use are-Glucose-vinegar, recognised chiefly by the presence of dextrin, which may be precipitated by alcohol; beer-vinegar, from sour ale; cider vinegar, made both from apples and pears; crab-vinegar, made from the crab apple, and used nearly all over Wales and Monmouthshire; spirit-vinegar made from alcohol; and various artificial vinegars. * Journ. d'Hyg., 1877, No. 45. TABLE XLVa.-THE COMPOSITION OF VARIOUS KINDS OF VINEGAR. The above table contains results reduced and collated from Sanglé Ferrière, Allen, Hehner, and others. § 288. Adulterations.-The adulterations of vinegar are— (1.) Water. (2.) Mineral acids, especially sulphuric, more rarely hydrochloric, and still more rarely nitric acids. (3.) Metallic adulterations, or rather impurities; such as arsenic (derived from sulphuric acid), copper,† lead, zinc, and tin, from the solvent action of the acid on any metallic surfaces with which it may have come in contact. (4.) Pyroligneous acid. (5.) Various organic substances, such as colouring agents, and capsicum. $289. Analysis of Vinegar.-(1.) Water.-Vinegar should contain at least 3 per cent. of acetic acid (C2HO2); a lower per "The observations of M. Deschamps induced us to analyse a vinegar sold by a certain Sieur C. The presence of arsenic in this vinegar was ascertained, and the Sieur C. was compelled to confess that the vinegar had been mixed with wood-vinegar. On resorting to the person who furnished the latter product, the whole of the wood-vinegar in his possession was found arsenical, and seized, in order to be employed only for industrial use.”--“ Le Vinaigre," Chevallier, Journ. d'Hyg., No. 46, June, 1877. + Seven out of twelve samples of vinegar sold in Paris, and analysed by Altred Riche, contained copper varying from 5 to 15 mgrms. per litre. Journ. Pharm. Chim. [4], xxvj. 23-28. Acetic Acid. Calculated Relation be tween Acid, and Extract. Ash. |