(_a_) Roccelline affords a violet colour. (_b_) Bordeaux, R. and B. „ blue „ (_c_) Panceau R., R.R., R.R.R. „ scarlet „ (_d_) Panceau, B. „ red „ (_e_) Biebrich red „ green to violet colour. (_f_) Tropeoline, O.O.O. „ red colour. (_g_) Tropeoline, O., and Chrysoidine „ orange-yellow colour. (_h_) Tropeoline, O.O. „ violet-red „ (_i_) Eosine „ yellow „ The method employed in the Paris Municipal Laboratory for the detection of dried fruit wine, or of added commercial glucose, is substantially the following:--A little beer-yeast is added to 300 c.c. of the suspected wine, and the mixture is allowed to undergo fermentation at a temperature of about 30°. When the fermentation is completed, the filtered liquid is introduced into a dialyser, the outer water of which is automatically renewed. The process of dialysis is continued until the outer water ceases to show a rotary effect when examined by the polariscope, after which it is neutralised with calcium carbonate and evaporated to dryness over the water-bath, with constant stirring. The residue obtained is treated with 50 c.c. of absolute alcohol and filtered, the insoluble matters being twice washed with 25 c.c. of alcohol. The alcoholic filtrates are next decolorised by means of animal charcoal, and evaporated to dryness, and the solid residue is dissolved in 30 c.c. of water and polarised. Genuine claret, when tested in this manner, fails to exhibit a rotary power, or is but slightly dextrogyrate, whereas fruit wines, and those containing artificial starch sugar, strongly rotate respectively to the left or to the right. The following are some of the conclusions arrived at by a commission, appointed by the German Government, to inquire into uniform methods for wine analysis, and establish standards of purity for genuine wine.[109] (_a_) After deducting the non-volatile acids, the extract in natural wine should amount to at least 1·1 gramme per 100 c.c.; after deducting the free acids, to at least 1 gramme per 100 c.c. (_b_) Most natural wines contain one part of ash to every 10 parts of extract. (_c_) The free tartaric acid should not exceed 1/6th of the total non-volatile acids. (_d_) The relation between the alcohol and glycerine varies in natural wines between 100 parts alcohol to 7 parts glycerine, and 100 parts alcohol to 14 parts glycerine. These proportions do not apply, however, to sweet wines. (_e_) Genuine wines seldom contain less than 0·14 gramme of ash, nor more than 0·05 gramme of sodium chloride per 100 c.c.