68 Effect of Tem2)eratures at or above 100° C. upon Vitamines. 



2. At temperatures in the neighbourhood of 120° C, however, there was a 

 swift destruction of anti-neuritic properties. This fact has an important 

 bearing where diets are largely composed of preserved and tinned foods 

 previously sterilised at temperatures above 100° C. 



[Addendum received August 2, 1917. — Since the above paper was written 

 the experiments with yeast extract alluded to on p. 65 have been completed 

 and the results set forth in Table II, above. 



The material used was a soluble yeast extract, made up to a solution of 

 convenient strength ; it contained about 35 per cent, of solids and 65 per 

 cent, of water. As before, the heating was done in a steam autoclave ; the 

 sohxtions to be heated were placed in large-sized test-tubes, in quantities not 

 exceeding 100 c.c. With this volume of liquid it was , found that there was 

 no significant delay in acquiring the temperature of the autoclave, if the test 

 tube were placed in position while the latter was still cool. 



The results obtained offer an interesting comparison with those of Table I 

 above, where the substance heated (wheat germ) was comparatively dry 

 (water content 10 to 14 per cent.). When due allowance is made for the 

 large margin of error inherent in this type of experiment (see preceding paper, 

 and p. 65, above), the results of Tables I and II are found to be in reasonable 

 accord with one another. After exposure to 100° C. for one hour, slight loss 

 of vitamine is evident in the yeast extract, a greater loss apparently than took 

 place with the wheat embryo at this temperature, see Table I, Expts. 2 and 3. 

 This may possibly be due to the excess of water contained in the extract. 

 In the neighbourhood of 120° C. destruction of the vitamine was rapid in 

 both cases.] 



BIBLIOGEAPHY. 



Chick, H., and Hume, E. M., ' Eoy. Soc. Proc.,' B (preceding paper). 

 Cooper (1913), 'Journal of Hygiene,' vol. 12, p. 436. 

 Eijkman(1906), 'Archiv f. Hygiene,' vol. 58, p. 150. 

 Grijns(1901), ' Geneesk. Tijdsclirift v. Ned. lud.' 

 Hoist (1907), 'Journal of Hygiene,' vol. 7, p. 619. 



