mine its specific gravity and refractometer reading at a suitable 

 temperature, obtaining from tables x the corresponding percentages of 

 alcohol. If the refractometer reading and the specific gravity both 

 correspond to the same percentage of alcohol, it is almost a certainty 

 that it is ethyl alcohol that is present, and that the substance under 

 examination contains the percentage of ethyl alcohol equivalent to 

 these constants. To render this an absolute certainty, the ethyl 

 ester of paranitrobenzoic acid is prepared from this distillate with 

 paranitrobenzoyl chlorid by the Baumann-Schotten method. 2 To the 

 solution containing the alcohol is added a slight excess of acid chlorid 

 and an equivalent amount of sodium hydroxid. Shake until the 

 odor of the acid chlorid disappears. This ester is a beautifully 

 crystalline solid which may be readily identified by its melting point 

 of 57 C. 3 This ester may be weighed, and while the yield obtained 

 is not quite quantitative (70 to 90 per cent of the theory when work- 

 ing with small quantities of alcohol), its weight serves as another 

 check on the percentage of alcohol present in the solution. If para- 

 nitrobenzoyl chlorid is not available the benzoic acid ethyl ester may 

 be prepared as just described, using benzoyl chlorid. The benzoic 

 acid ethyl ester may be weighed (yield practically quantitative) , and 

 identified by its odor and its boiling point, 212 C., using for the latter 

 purpose the convenient method for determining the boiling point of 

 very small quantities of liquids recently proposed by Smith and 

 Menzies. 4 



As to the qualitative detection of ethyl alcohol, two tests used 

 together, the formation of iodoform and the formation of ethyl 

 benzoate would render the presence of ethyl alcohol probable, for 

 the only benzoic ester whose odor is similar to that of the ethyl ester 

 is the methyl ester, and methyl alcohol does not give the iodoform 

 reaction. 5 A little careful consideration of the question, however, 

 will make it evident that for an absolutely unassailable result, when 

 ethyl alcohol is present in small amounts, some such method as that 

 just outlined for the determination of this substance must be used. 

 After the alcohol is concentrated as described, other confirmatory 

 tests, such as the determination of the freezing point, the boiling 

 point, the capillarity constant, the electrical conductivity, or the 

 preparation of other esters, may be applied to the liquid. 



It has been attempted to describe in a general way such tests as 

 can be easily made and which prove absolutely that an aqueous 

 liquid contains a definite quantity of ethyl alcohol. It is realized, 



1 Tables of Ackermann and Steinmann, Zts. gesam. Brauwesen, 1905, 28: 259; Doroszewski and Swor- 

 zanczyk, J. Russ. Phys. Chem. Soc., 1907, 40: 101-125. 



2 Ber. d. chem. Ges., 1884, 17 : 2445 ; 19: 3219. 

 Ber. d. chem. Ges., 1905, 88 : 620. 



J. Amer. Chem. Soc., 1910, 32 : 897. 



6 The limit of these reactions is about 0.1 per cent of ethyl alcohol. 



