ARTHUR ISAAC KENDALL 239 



of glucose, are found to be quite rich in formic acid even after forty-eight hours' 

 incubation. 



According to Frankland and Frew,' the decomposition of formic acid is more 

 complete under conditions where oxygen is rigorously excluded. It is worthy of note 

 that the equation involving the cleavage of formic acid to carbon dioxide and hy- 

 drogen does not involve the interreaction of H and OH ions; nearly all true enzymic 

 processes do. 



Butyric acid fermentation. — Mention has already been made of Pasteur's dis- 

 covery^ that certain anaerobic "vibrios" could produce butyric acid from lactates. 

 This involves a synthetic process, whereby the four-carbon-atom chain of butyric 

 acid is formed from the three-carbon-atom chain of the lactic acid. Neuberg and 

 Arinstein^ have studied the butyric acid fermentation induced by Bacillus butylicus 

 fitzianns, and find by the Anfangverfahren procedure that both butyric acid and butyl 

 alcohol are produced if sulphites are added to the slightly alkaline cultural media. 

 Acetaldehyde was also detected in these cultures, and it seems probable that a syn- 

 thetic process is involved much like that noted by Pasteur more than sixty years ago. 



Acetic acid fermentation. — The industrial production of acetic acid from alcohol 

 has long been practiced, but the process has not been very well understood other than 

 that there was an oxidation of the alcohol to the acid. Recently Neuberg and Win- 

 disch^ have brought forward evidence which seems to show that the process is some- 

 what more intricate than a mere addition of oxygen to the alcohol molecule, thus: 



C,H30Hv C.H.OH. C.H5OH. 



CH3 . CHO*<' CH3 . CHO*<' CH3CHO,* etc. 



CH3 • COOK CH3COOH 



*Cannizzaro reaction. 



It is of great interest to recall that Liebig,^ over fifty years ago, showed that the 

 change of alcohol to acetic acid took place in two steps: (i) removal of hydrogen from 

 the ethyl alcohol molecule to form acetaldehyde, and (2) the addition of oxygen to 

 the acetaldehyde molecule to form acetic acid. 



Glycerol fermentation. — Glycerol is fermented by many bacteria; some, like the 

 Shiga type of dysentery bacillus, produce acid from this triatomic alcohol, while 

 many members of the mucosus capsulatus group of bacteria evolve gas during its fer- 

 mentation. Very little is known as yet of the chemical change involved. 



Voges-Proskauer reaction. — The three equations discussed above represent, as well 

 as available information affords, the course of fermentation of simple sugars by the 

 majority of ordinary bacteria, with and without gas production. Nevertheless, they 

 apparently do not provide a complete summary of the products of fermentation 



• Frankland, P. F., and Frew, W.: loc. cit. 



^ Pasteur, L. : loc. cit. 



3 Neuberg, C, and Arinstein, B.: Blochem. Zlsckr., 117, 269. 1921. 



"i Neuberg, C, and Windisch, F.: Biochcm. Ztschr., 166, 454. 1925. 



5 Quoted by Hofmann, A. W.: Faraday Lecture for 1S75, p. 112. Macmillan and Co., 1876. 



