358 



SCIENCE. 



[N. S. Vol. II. No. 38. 



Eecent investigations have clearly shown 

 that atmospheric nitrogen plays an impor- 

 tant part in the nutrition of plants. The 

 assimilation of nitrogen from the atmos- 

 phere can only result from the activity of a 

 microbe which is present in the soil. Fer- 

 tility of the soil is, in case of certain plants, 

 largely dependent upon the existence of 

 this bacterium. It is probable that a study 

 of the part played by the bacteria in the 

 soil will prove of gi-eat importance. The 

 results already obtained in introducing 

 bacteria into the soil have been most 

 encouraging in the case of certain plants. 



The paper was discussed by Profs. G. E. 

 Patrick, J. L. Howe and W. O. Atwater. 

 Prof. Atwater described the experiments 

 which are being conducted in this countiy 

 and abroad to determine comparative values 

 of foods and the quantities of food required 

 by people of different classes and occupa- 

 tions. 



A paper by Prof. Milton Whitney, on 

 ' Recent Progress in the Analysis of Soils,' 

 was omitted owing to the absence of the 

 author. Mr. J. T. Morehead read a paper 

 on ' Calcium Carbide.' The author de- 

 scribed the process of manufacture in an 

 electric farnace. The furnace is con- 

 structed of ordinary brick and is covered. 

 Vertically supported carbon rods, 4 inches 

 thick, constitute the positive electrode. A 

 plate of iron at the bottom of the furnace, 

 covered by a layer of carbon, forms the neg- 

 ative electrode. The charge consists of a 

 mixture of ground lime and coke. 



A current of 100 volts and 1700 amperes 

 produces <S0 pounds per hour of calcium car- 

 bide. The product is a hard crystalline 

 substance having the composition Ca Cg. 

 Immersed in water it is decomposed with 

 violence but \\ath very little heat, and yield- 

 ing slacked lime almost white in color. 

 Five cubic feet of acetylene gas are pro- 

 duced l)y one pound of carbide. Large 

 quantities of the carbide are now being 



manufactured by the Wilson Aluminum 

 Company La their works situated at Spray, 

 IST. C. After a tribute of thanks to Dr. Wm. 

 McMurtrie, Vice-President of the Section of 

 Chemistry, the Section adjourned. 



SECTION D. MECHANICAL SCIENCE AND EN- 

 GINEERING. 



The chairman of Section D, William 

 Kent, of Passaic, N. J., and the secretary, 

 Professor Henry S. Jacoby, of Ithaca, N. 

 Y., were both present throughout the meet- 

 ing of the Association. The Vice-President's 

 address, which is published on page 321 of 

 Science, was delivered on Thursday after- 

 noon, August 29th, and excited more than 

 usual interest outside as well as in the Sec- 

 tion by its able exposition of the work of 

 the engineer as related to economic pro- 

 gress. 



The papers were read on Friday. That 

 of H. N. Ogden, of Ithaca, N. Y., treated 

 of the ' Economics of Engineering Public 

 Works.' After an introduction referring to 

 the extravagance of the American people, 

 and to the influences which favored individ- 

 ual action and rendered unnecessarj' the 

 combination of interests by cooperation un- 

 til recently, instances were given of cor- 

 porations seeking advantage at the expense 

 of the public good. The tearing-up of city 

 streets, and digging one trench for gas 

 pipes, another for water pipes, and others 

 for sewers and steam pipes, without any 

 mutual ai-rangement, was given as an illus- 

 tration of the most common lack of econ- 

 omj' in municipal affairs, as the jieople ulti- 

 mately pay for all the trenches and suffer the 

 loss incident to breaking up the streets so 

 frequently, interfering with traffic and often 

 ruining the paving. Similar extrav.agance 

 is seen in the conduct of elections and the 

 assessment and collection of taxes. Nu- 

 merous instances of the ability of our peo- 

 ple to adapt means to ends, to devise new 

 methods to changed conditions, give hope 



