VITAMIN C 183 



they found that while fuller's earth and dialyzed iron adsorbed almost 

 all of the antineuritic vitamin, such treatment did not affect the anti- 

 scorbutic activity. Similarly, orange juice did not lose its activity on 

 filtration through a Berkfeld candle. 



Harden and Zilva (1918d) also studied the susceptibility of the 

 antiscorbutic substance to alkalinity by experiments upon guinea pigs 

 receiving oats, bran and autoclaved milk with measured addenda of 

 orange juice which was fed in some cases fresh and unchanged, in 

 other cases neutralized immediately before feeding, while in still other 

 cases the juice was made alkaline and allowed to stand for some time 

 before being fed. Of freshly expressed orange juice, from 3 to 5 cubic 

 centimeters was always sufficient to keep guinea pigs in good con- 

 dition and free from any symptoms of scurvy. Three guinea pigs 

 receiving respectively 3, 5, and 7 cubic centimeters of orange juice 

 which had just been rendered neutral to phenolphthalein were also 

 protected from scurvy. On the other hand, doses of 3, 5, and 7 cubic 

 centimeters of an orange juice which had been made twentieth-normal 

 alkaline by addition of sodium hydroxide and then allowed to stand 

 24 hours in a cold room before feeding did not protect. That this was 

 due to destruction of the antiscorbutic vitamin and not to any effect 

 of the alkali upon the animal was shown by the fact that the results 

 were unchanged when the juice which had been thus treated was re- 

 acidified immediately before being fed. In a final experiment to test 

 the effect of less drastic treatment, the juice was made fiftieth-normal 

 alkaline by addition of sodium hydroxide and later in the same day 

 fed in doses of 3, 5, and 7 cubic centimeters respectively to three guinea 

 pigs. All died of scurvy, though not so quickly as those receiving the 

 basal diet only, showing that a considerable part but not all of the 

 antiscorbutic vitamin was destroyed by this treatment. 



Hess (1918) reported that orange juice, boiled and slightly alka- 

 linized, constitutes an excellent antiscorbutic agent for intravenous 

 use in infantile scurvy, but that in such cases the juice should be used 

 immediately and not kept in the alkaline condition. 



Hess and Unger (1918a) in a study of guinea pig scurvy reported 

 that orange juice lost some of its antiscorbutic power after storage in 

 a refrigerator for three months, that the antiscorbutic substance of 

 orange juice could be extracted with 95 per cent alcohol, and that 

 orange peel after being dried and kept dry for three months still showed 

 antiscorbutic properties. Prunes seemed, in their experiments, to have 

 no value as an antiscorbutic, and the question naturally suggests itself 

 whether the practice of dipping prunes in alkaline solution in connec- 



