Dr. A. Dupre on the Elimination of Alcohol. 



271 



denser in connexion with a receiver, and finally escapes into the air. The 

 experiment is conducted as follows : — The bag being empty, the water in the 

 flask is heated to boiling, and the breath is blown into the apparatus for a 

 quarter to half an hour. The breath is first deprived of most of its moisture 

 by the chloride of calcium, and next enters the bag dry, or nearly so. From 

 the bag it passes, at considerably reduced speed, through the flask, where 

 it becomes mixed with steam, into the condenser. In this last the steam is 

 condensed, and with it the greater part of the alcohol vapours present. 

 The alcohol will therefore be found in the distilled water collected in the 

 receiver. When the breath has been blown into the apparatus during the 

 desired length of time, the blowing is discontinued, the tube is closed by a 

 clamp, and the air collected in the bag is allowed to pass gradually 

 through the retort and condenser. The chloride of calcium is now dissolved 

 in water, the solution is added to the distillate collected, and the alcohol 

 therein contained is estimated by repeated distillations, oxidation, &c, as 

 described in the case of urine. If it is desired to blow for a greater length 

 of time than half an hour, it is necessary, with a bag of the above size, to blow 

 it up twice, each time of course allowing all the air collected to pass out 

 through the retort and condenser. At first it is difficult to keep up the 

 ordinary rate of respiration while blowing into the bag ; but with a little 

 practice this "becomes easy, and a bag holding about 4 cubic feet will then 

 suffice for half an hour's breathing. At the end of this time about 4 cubic 

 feet of air should be in the bag, while 2 cubic feet have passed through the 

 apparatus ; the bag will then take one hour more to become empty. The 

 bag has thus to serve both as a reservoir and regulator, reducing the 

 velocity of the air-current to about one third. The desired velocity is 

 readily obtained by a proper adjustment of the weights on the pressure- 

 boards. The boiling of the water in the flask is regulated so as to give about 

 half a litre distilled water for every 12 cubic feet of air passing through. The 

 breath was blown through the apparatus for half an hour. The fol- 

 lowing quantitative experiments, made under precisely the same condi- 

 tions as the experiments with the breath, will serve to show that the greater 

 part of the alcohol carried by the air is condensed with the steam. A 

 given quantity of alcohol was evaporated in a current of air, which was 

 afterwards passed through the apparatus at the same speed as the breath. 

 In the distillate obtained, the alcohol was estimated as described. The 

 amount of air taken was 12 cubic feet, equivalent to about one hour's 

 breathing, and necessitated the filling of the bag twice. 



First experiment. — Amount of alcohol evaporated 004 gramme ; 

 acetic acid obtained neutralized 0-67 cub. centim. d. n. soda, equivalent to 

 0*031 gramme alcohol. 



Second experiment. — Amount of alcohol evaporated 0*008 grm. ; acetic 

 acid obtained neutralized 1*25 cub. centim. d. n. soda, equivalent to 

 0*0058 grm. alcohol. 



Third experiment, — Amount of alcohol evaporated 0*0415 grm. ; acetic 



