The methods adopted by the "Union of Bavarian Chemists" differ considerably from the above in many particulars, so they are given also, together with the methods adopted by the same body for the examination of beer1 in somewhat condensed form.

Methods Of Investigation

I. Determination of specific gravity. - This is to be done by means of a Westphal's balance or a picnometer, and always at 15° C.

II. Determination of extract. - Ten to 50cc. wine at 15° C. are evaporated in a platinum dish on the water bath to the proper consistence and then dried in a drying oven at 100 C. to constant loss of weight. Constant loss of weight is assumed when three weighings, with equal intervals between the first and second and second and third give equal differences between the successive weighings.

Weighings are to be made at intervals of fifteen minutes.

III. Inorganic matter. - This is the incombustible ash obtained by burning the extract. Repeated moistening, drying, and heating to redness are advisable to entirely get rid of all organic constituents.

IV. Acidity. - After shaking vigorously, to drive off carbonic acid, the wine is to be titrated with an alkali solution and the acidity expressed in terms of tartaric acid.

V. Glycerine. - (1) This is determined in dry wines as follows : The alcohol is driven off from 100cc. wine, lime or magnesia added, and the mass evaporated to dryness The residue is boiled with 90 per cent. alcohol, filtered, and the filtrate evaporated to dryness. This residue is dissolved in 10-20cc. alcohol, 15-30cc. ether added, and the mixture allowed to stand until it is clear. It is then decanted from the sticky precipitate into a glass-stoppered weighing bottle, evaporated to constant loss of weight, and weighed.

(2) The following method is employed for sweet wines: l00cc. wine are measured into a porcelain dish and evaporated on the water bath to a sirupy consistence, mixed with 100-150cc. absolute alcohol, poured into a flask, ether added in the proportion of 1 1/2 volumes to each volume of alcohol used, the flask well shaken, and allowed to stand until the liquid becomes clear. This is then poured off and the residue again treated with a mixture of alcohol and ether. The liquids are mixed, the alcohol and other driven off, the residue dissolved in water, and treated as in (1).

(3) In all glycerine determinations it is necessary to take into consideration the loss of glycerine due to its volatility with water and alcohol vapor, and accordingly to add to the glycerine found 0.100 gram for each l00cc. of liquid evaporated.

(4) It is necessary to test the glycerine from sweet wines for sugar, and if any is present it must be estimated by Soxhlet's or Knapp's method and its weight subtracted from that of the glycerine.

VI. Alcohol. - The determination must be made by distillation in glass vessels and the results stated as follows: 100cc. wine at 15° C. contain x grams or cubic centimeters alcohol.

VII. Polarization. - 1) The wine is decolorized with plumbic subacetate.

Hilger, Vereinbarungen u. s. w., p. 154.

4450 - No. 13, pt. 3 ---- 9

(2) A slight excess of sodic carbonate is added to the filtrate from (1). Two cubic centimeters of a solution of plumbic subacetate are added to 40cc. white wine and 5cc. to 40cc. red wine, the solution is filtered and 1cc. of a saturated solution of sodic carbonate added to 21 or 22.5cc. of the filtrate.

(3) The kind of apparatus used and the length of the tube are to be given, and results estimated in equivalents of Wild's polaristrobometer with 200mm. tubes.

(4) All samples rotating more than 0.5° to the right (in 220mm. tubes, after treating as above), and showing no change, or but little change, in their rotatory power after inversion, are to be considered as containing unfermented glucose (starch sugar) residue.

(5) Rotatory power of less than 0.3° to the right shows that impure glucose has not been added.

(6) Wines rotating between 0.3° and 0.5° to the right must be treated by the alcohol method.

(7) Wines rotating strongly to the left must be fermented and their optical properties then examined.

VIII. Sugar. - This is to be determined by Soxhlet's or Knapp's method. The presence of unfermented cane sugar is to be shown by inversion, etc.

IX. Potassic bitartrate. - The determination of potassic bitartrate as such is to be omitted.

X. Tartaric, malic, and succinic acids. - (1) According to Schmidt and Hiepe's method.

(2) Determination of tartaric acid according to the modified Berthelot-Fleury method.

(3) If the addition of 1 gram finely powdered tartaric acid to 100 grams wine produces no precipitate of potassic bitartrate, the modified Berthelot-Fleury method must be employed to determine free tartaric acid.

XI. Coloring matter.-(1) Only aniline dyes are to be looked for.

(2) Special attention is to be paid to the spectroscopic behavior of rosaniline dyes, as obtained by shaking wines with amyl alcohol before and after saturation with ammonia.

(3) A qualitative test for alumina is not sufficient evidence of the addition of alum.

XII. Nitrogen. - To be determined according to the ordinary method.

XIII. Citric acid. - Presence to be shown by a qualitative test, as baric citrate.

XIV. Sulphuric acid. - To be determined in the wine after adding hydrochloric acid.

XV. Chlorine. - To be determined in the nitric-acid solution of the burnt residue by Volhard's method.

XVI. Lime, magnesia, and phosphoric acid. - These are determined in the ash fused with sodic hydrate and potassic nitrate, the phosphoric acid by the molybdenum method.

XVII. Potash. - Either in the wine ash, as the platinum double salt, or in the wine itself, by Kayser's method.

XVIII. Gums. - Presence shown by precipitation by alcohol; 4cc. wine and 10cc. 96 per cent. alcohol are mixed. If gum arabic has been added, a lumpy, thick, stringy precipitate is produced; whereas pure wine becomes at first opalescent and then flocculent.