196 



SCIENCE. 



[N. S. Vol. XXIY. No. 607. 



The amount of ammonia depends on the 

 nature of the soil. The question arises as 

 to the reason why one soil will lead to the 

 formation of more ammonia than another 

 soil under the same conditions. Are the 

 differences due to the numbers or kind of 

 bacteria or are they due to variations in the 

 chemical composition of the soil 1 Experi- 

 ment has demonstrated that the bacterio- 

 log:ical factor has been found to play the 

 predominant role in the ammonification of 

 soil nitrogen and that it is itself directly 

 affected by the chemical composition of the 

 soil. 



The detailed results of these studies will 

 be rep6rted in the Journal of the American 

 Chemical Society. 



Compositimi of the Drainage Waters of 

 'Some Alkali Tracts: F. K. Cameron. 

 It was shown how the analysis of a drain- 

 age water could be used in interpreting 

 the changes taking place in alkali soils 

 under drainage. Illustrations were given, 

 on the one hand, showing that the same 

 salts present in the soil remain, though 

 the total amount had been diminished, and 

 on the other hand, illustrations were given 

 where not only the amount of salts, but the 

 particular kinds of salts, had changed. 



Nutrition Investigaiion of the Office of Ex- 

 periment Stations, and the Results of 

 Some Recent Work: C. F. Langwortht. 

 The purpose and scope of the human 

 nutrition investigation carried on under 

 the auspices of the Office of Experiment 

 Stations of the Department of Agriculture, 

 were briefly outlined, particularly the work 

 -of the fiscal year 1905-6, and the results 

 of some dietary studies with aged men and 

 women were summarized. From the data 

 presented and a summary of similar work, 

 the factor nine tenths was proposed as rep- 

 resenting the amount consumed by a man 

 past middle life, as compared with a man 

 in full vigor at moderate muscular work. 



Keeping of Tohacco: J, M. Bell, 



This article has been published in full 

 in Science, June 16, 1906, 



A Method for the Determinaiio^i of the 

 Lead Numiber in Maple Syrups and 

 Maple Sugar: A, L. Winton and J. 

 Lehn Kreideb. 



The method proposed is based on the 

 well-known fact that lead subacetate pro- 

 duces a voluminous precipitate in genuine 

 maple products, whereas in products 

 adulterated with refined cane sugar the 

 amount is deficient. A solution of 25 

 grams of the material is precipitated with 

 25 c.c. of standard lead subacetate, made 

 up to 100 cc, filtered, and the lead deter- 

 mined in 10 cc. of the filtrate. The amount 

 of lead consumed in forming the precipitate 

 is found by difference. This expressed as 

 per cent, of the material is the 'lead num- 

 ber.' The lead number in samples of 

 maple syrups of known purity was not less 

 than 1,20, but in adulterated samples it 

 ranged from 0.02 to 0.92. 



The Application of Colorimetric and Other 

 Delicate Analytical Methods to the Study 

 of Agricidtural Problems: Ostwald 

 ScHREiNEB and J. F. Breazeale. (By 

 title.) 



Legume Bacteria and Soil Fertility: Karl 

 Kellerman. (By title.) 



Toxicity of Some Ammonium Salts on 

 Wheat Seedlings in Solution Cultures: 

 Charles A. Jensen, (By title.) 



A Preliminary Study of the Combinations 

 of Acids with Casein as determined l>y 

 Co7iductivity Measurements: L. L. Van 

 Slyke. 



For more than half a century there has 

 been at issue a question as to whether or 

 not the coagulum formed when milk sours 

 or is acted on by acids is a combination of 

 casein and acid. As the result of work 

 carried on in the Geneva Station Labora- 



