340 FOOD AND FOOD ADULTERANTS. 



offices in Germany, decided upon by the "Berlin Commission ; " third, 

 the methods adopted by the Bavarian chemists. 



It would seem that in France and Germany, where wine analysis 

 has been carried on for so many years, and to so large an extent, the 

 methods in use would be as well denned and exact as is possible in such 

 work; nevertheless, none of the methods have been accepted without 

 a thorough trial of their accuracy, unless otherwise indicated. 



The estimation of several of the constituents of wine is so similar to 

 the same determination in beer, that it will be necessary simply to refer 

 to the part on beer analysis, thus avoiding unnecessary repetition. 



SPECIFIC GRAVITY. 



This is taken with the picnometer, in the same manner as with beer. 



ALCOHOL. 



The estimation of the alcohol can be made in the same manner as in 

 beer, with a few precautions. Thus, in the distillation method it is bet- 

 ter to neutralize the sample taken with carbonate of soda, or standard 

 alkali, and a slight addition of tannin will generally be found necessary 

 to prevent frothing. If the indirect method is used, more accurate re- 

 sults will be obtained by neutralization of the sample taken by shaking 

 up with magnesia before the specific gravity is taken. In the present 

 work I have made use of the distillation method exclusively, weighing 

 out the sample taken, about 50 grams, making up to about lOOcc., and 

 distilling off 50ce., which is also weighed. Tables for the calculation 

 of alcohol content from the specific gravity have already been given 

 page 285). 



EXTRACT OR TOTAL SOLIDS. 



The determination of the extract in wine presents the same difficul- 

 ties as with beer on account of the content of glycerine, which is greater 

 in the former than the latter. For this reason the indirect method would 

 seem especially applicable, but the difficulty here is that there is a larger 

 amount of volatile acid present, which is only partially driven off with 

 the alcohol, and the solution density of the solids of wine have not been 

 so well established as that of malt extract, so that different tables and 

 factors vary widely. 1 



For the direct estimation the French method is to evaporate 25cc. 

 in a flat-bottomed dish, with vertical sides, and dry the residue to a con- 

 stant weight in a water bath. The Berlin method is as follows: 



EXTRACT. 



Fifty cubic centimeters of wiue are measured (at 15 C.) into a platinum dish (K">mm. 

 in diameter, 20mm. in height, and of 75cc. capacity, weight about 20 grams), evap- 

 orated on the water bath, and the residue heated 2.} hours at 100 C. Of wines rich 

 iu sugar, i. e., containing over 5 grams sugar in lOOcc., a smaller amount should bo 

 taken, so that the weight of extract shall not exceed 1, or at most !.."> grams. 



1 P.aiimrrt found in his work on California wines that the tables of Schul/c (/eit 

 Anal. Chcm., 1880, KM) intended for beer extraets ave results in Hie indirect estima- 

 tion \vliidi approximated much more closely to the results by direct estimation than 

 figures obtained from I lager's tables (Cheiu. Cent.. 1H7*. !!.>), which wero intended 

 especially for wine extract. 



