28 SCIENCE PROGRESS 



of acetic acid from acetylene and the significance of these was 

 pointed out in view of the possible shortage of the usual sources 

 of supply. The question is evidently occupying the minds of 

 French chemists as well, since a French patent (No. 479,656) 

 has recently been granted. It is claimed by the patentee that 

 the mercury salt required for bringing about the combination 

 between acetylene and water should be dissolved in acetic 

 acid. The oxidation of the acetic aldehyde to acetic acid is 

 effected by adding oxidising agents such as hydrogen peroxide, 

 perborates, permanganates, percarbonates, dichromates, ozone, 

 etc., or by means of oxygen or air in the presence of catalysts 

 such as cerium salts, vanadium pentoxide and other sub- 

 stances. A continuous production of acetic acid is obtained 

 by passing 130 parts of acetylene and 80-100 parts of oxygen 

 into a mixture of 400 parts of glacial acetic acid, 100 parts of 

 water, 50 parts of mercuric nitrate, and 10 parts of cerium 

 oxide at 50-1 oo°. From time to time the acetic acid is drawn 

 off and distilled, the residue being returned to the reaction vessel. 



The catalytic dehydrating action of alumina at high 

 temperatures has been known for some time and the property 

 has recently been employed by C. D. van Epps and E. Emmet 

 Reid (/. Amer. Chem. Soc. 1916, 38, 2128) for the preparation 

 of acetonitrile by passing acetic acid vapour mixed with a 

 moderate excess of ammonia over alumina heated at 500 . 

 The yield may be as high as 85 per cent., but is influenced by 

 the activity of the catalyst and the rate of flow of the gases, 

 and is lowered by the presence of water in the acetic acid. 



Reference has already been made in these columns (Science 

 Progress, October 1916, No. 42, p. 280) to the possibility of 

 the purine ring being synthesised in the animal body from 

 the two degradation products of protein, arginine and histidine. 

 Further evidence in support of this view is furnished by a paper 

 by H. Ackroyd and F. G. Hopkins (Biochem. J. 19 16, 10, 551). 

 It has already been observed that the removal of arginine and 

 histidine from the diet of rats was accompanied by a rapid 

 fall of body weight and a diminished excretion of allantoin, 

 the end point of protein metabolism in rats ; it is now found 

 that the removal of either one of these two acids does not 

 cause a loss of body weight, or in other words that equilibrium 

 can be maintained in the absence of one of these acids, but 

 not of both. This is explained by assuming that in meta- 



