PRODUCTION OF ACIDS FROM ALCOHOLS, ETC. 91 



in the incubator and the following observations made 

 (Th. Smith): 



1. If cloudiness occurs only in the open limb, then one 

 is dealing with an aerobic variety; if only the fluid in the 

 closed limb becomes cloudy, while that in the bulb re- 

 mains clear, then an anaerobic variety is present. 



2. One notes the daily gas-formation by an ink mark, 

 and, if the tubes are graduated, in four to six days, after the 

 gas production has ceased, the percentage of gas formed on 

 each day can be determined. 



3. A rough analysis of the gas is made. With this 

 object in view, after indicating the quantity of gas pro- 

 duced by means of a mark, the open bulb is completely 

 filled with 10% solution of caustic soda and closed tightly 

 with the thumb. The fluid is shaken thoroughly with 

 the gas and allowed to flow back and forth from bulb to 

 closed branch and the reverse several times. Finally, the 

 gas is allowed to again rise in the closed limb, and after 

 removing the thumb, the new volume of gas is read. The 

 part removed consists of CO 2 ; that remaining consists of 

 nitrogen, hydrogen, and marsh-gas. For quantitative 

 analysis of these gases it is best to employ Hempel's gas 

 pipet. (Compare Cl. Winkler, Lehrbuch der techn. Gas- 

 analyse, Freiberg, 1892. ) The principle of the method is 

 that hydrogen mixed with oxygen carried over red-hot pal- 

 ladium asbestos is converted into water, thus disappear- 

 ing; marsh-gas in a red-hot platinum capillary is burned 

 up to carbonic acid, and as such is determined; what is 

 left is nitrogen. With some practice the investigation is 

 easy and accurate. 



15. Production of Acids from Alcohols and from Other 

 Organic Acids. 



The transformation, in weak solutions, of ethyl alcohol, 

 under energetic consumption of oxygen, into acetic acid 

 by the Bact. aceti or its nearest relatives has long been 

 known (compare p. 66 and special part) : 



CH 3 + 2 =:CH3 + 

 CH 2 OH COOH 



