816 EXPERIMENT STATION RECORD. [Vol.43 



College, London, are reported in which it was found that the ordinary organic 

 manures, which are generally applied to soils in agricultural and horticultural 

 operations, namely, leaf mold and fresh and well-rotted stable manures, contain 

 water-soluble substances in varying proportions which are effective as plant 

 growth-promoting substances or auximones. Such ingredients were also found 

 in well-manured fertile soil. 



A comparison between fresh and well-rotted stable manures showed that in 

 all cases, in whatever proportions the materials were used, the extract of 

 rotted manure was more effective than that of the fresh material, while an ex- 

 tract of peat, which had been artificially subjected to bacterial decomposition, 

 was more effective than either. The increase in growth following the addition 

 of these materials to the culture solutions was such as could not be attributed 

 to the purely nutritive value of the materials added, and all these composts 

 are, therefore, assumed to contain growth-promoting substances. The amount 

 of these substances varied directly with the extent of the bacterial decomposi- 

 tion of the material, which was found to be an important factor in determining 

 the practical effectivenss of the composts. 



Microscopic examinations showed that the various auximones have a marked 

 influence on the size and contents of the cell, especially on the nucleus. A de- 

 tailed examination was, therefore, made of well-manured soil, leaf mold, and 

 fresh and well-rotted stable manures to determine their content of derivatives 

 of nucleic acid. It was found that all these materials contain appreciable 

 quantities of nucleic acid and its derivatives in various stages of decomposition. 

 The greater the extent of the decomposition, the more effective was a water ex- 

 tract of the material when added to a culture solution. Assuming that the 

 whole effect is due to nucleic acid or its derivatives, it appeared that the free 

 bases, individually or collectively, are of more value as growth-promoting sub- 

 stances than the nucleic acid. It is considered evident, therefore, that part 

 at least of the beneficial effect of organic manures must be due to the direct 

 value of these substances to plants. 



The catalytic oxidation of ammonia to nitric acid, B. Neumann and H. 

 Rose {Ztschr. Angew. Chem., Aufstazt., 33 (1920), Nos. 14, pp. 41-44; 16, pp. 45- 

 48, figs. 5; 18, pp. 51-55, figs. 6). — A series of experiments on the oxidation of 

 ammonia to nitrates with different contact substances, such as platinum and the 

 oxids of iron, chromium, copper, and vanadium are reported, and the results 

 compared with the findings of other investigators. 



The possible and actual reactions entering into the process are discussed, and 

 the influence of ammonia concentration, current speed, and temperature studied. 

 The best results were obtained with platinum with a 96 per cent transformation 

 at 500" C. iron oxid with 90 per cent transformation at 670°, and iron bismuth 

 oxid with 95 per cent transformation at 600". 



Diagrams showing the gas composition for these three catalyzers for tem- 

 peratures of from 300 to 700' are given. On the basis of the gas compositions 

 established, the temperatures of reaction for certain gas mixtures are computed, 

 showing that under determined conditions the transformation of ammonia to 

 nitrates is possible without further additions of heat. 



Relative value of acid phosphate and rock phosphate on North Carolina 

 soils, C. B. Williams, W. F. Pate, E. C. Blaib, S. C. Clapp, and F. T. Meacham 

 {Bui. N. C. Dept. Agr., 41 (1920), No. 6, pp. 22, figs. S).— Experiments on the 

 relative value of acid phosphate and rock phosphate conducted on several 

 experimental farms in North Carolina are reported. 



At the Buncombe farm, acid phosphate was found to give larger crop yields 

 than rock phosphate when both were used (1) with nitrogen and potash, 

 (2) with stable manure, and (3) with potash and legumes turned under. On 



