198 proceedings: chemical society 



these cultures. It was iound that the character of the medium did not 

 affect the results. The presence of a few parts per million of calcium 

 enabled the plants to overcome to a large extent the injurious effect of 

 the alkali, altho the plants absorbed as much alkali in the presence of 

 lime as they did in the control cultures. (Author's abstract.) 



Discussion: Cameron questioned first whether the beneficial action 

 of clay might not have been due to absorption, second whether sodium 

 chloride found in the ash might not have been present in sap streams. 

 In reply to an inquiry by Sosman, LeClerc stated that petroleum coke 

 was the form of carbon used in the absorption experiments. C. C. Moore 

 inquired as to the bearing of these experiments on the toxic excreta 

 theory. Johnston suggested that the absorption of sodium chloride was 

 a chemical reaction in the case of clay, and a surface effect in the case of 

 carbon. Salant inquired concerning the effect of calcium salts alone, 

 and Cameron stated that calcium chloride was toxic in high concen- 

 tration. 



H. C. Gore, of the Bureau of Chemistry: The estimation of tartaric 

 and malic acids by the use of uranium acetate and ammonium molyhdate. 

 The effect was shown of increasing amounts of uranyl acetate added to 

 solutions of free and neutralized malic and tartaric acids respectively. 

 Excessive amount of uranyl salt were found to cause depressions in the 

 very high optical rotations observed. In case of malic acid the depres- 

 sions were slight and the maximum activity could be restored by adding 

 optimum amounts of acetic acid; in case of tartaric acid the depres- 

 sions due to excess of uranyl salt were much larger and the readings were 

 only slightly increased by addition of acetic acid. Ammonium molyb- 

 date caused very large increases in specific rotatory power of the two 

 acids. In the case of malic acid the maximum polarizations were much 

 less for the neutralized than for the free acid; small additions of acetic 

 acid stimulated the polarizations very greatly, and in presence of suitable 

 amounts of acetic acid and ammonium molybdate the relation between 

 the malic acid present and the polarizations was found to be linear. 

 With tartaric acid the rotations shown when the free acid was treated 

 with ammonium molybdate were higher than when the neutralized 

 acid was used. The stimulating effect of acetic acid, while large, was 

 smaller than with malic acid. Conditions were not found under which 

 the relation between the polarizations and amounts of tartaric acid 

 present were linear, but the specific rotatory power increased with 

 increasing concentration. (Author's abstract.) 



Discussion: Hillebrand suggested the use of the method inversely 

 for the rough estimation of uranium and molybdenum in ores. 



Robert B. Sosman, Secretary. 



