564 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



American Institute Polytechnic Association, ) 



March 30, 1865. } 

 Prof. Samuel D.. Tillman in the chair. Benjamin Gurvey, secretary. 



Starting Railroad Cars. 



Mr. Lawton exhibited a model of his plan for assisting horses to start 

 cars. The most severe labor and consequent injury to horses on railroads 

 arises from the violent straining in their efforts to start a heavily loaded 

 car, particularly on an up grade. This plan consists of a ratchet-wheel 

 fixed on the center of the axle, into which a lever having a short and long 

 arm catches when the car is stopped. On starting again, the horses pull 

 on the long arm of the lever, which turns the wheels a short distance, just 

 enough to give the car a start. The contrivance is simple, and acts on 

 well known mechanical principles. 



The chairman read the following items of scientific news : 



Influence of Soils in the Production of Ammonia from Air 



AND Water. 



M. Decharme, of France, in order to determine whether arable soil under 

 ordinary conditions is capable, simply by virtue of its porosity and the in- 

 fluence of humidity, of transforming part of the atmospheric nitrogen which 

 penetrates and traverses it, into ammonia or ammoniacal salts, made the ' 

 following among other experiments: 



He passed 200 litres of air (at the rate of ten litres per hour) freed from 

 its natural ammonia, over 250 grammes of ordinary vegetable earth pre- 

 viously calcined and washed or estimated relatively as to its total of nitro- 

 gen, then restored to its usual state of humidity, and raised progressively 

 from lO^'to about 50"* C. He found that part of the nitrogen of this air 

 had been transformed into ammonia, into carbonate and nitrate of ammonia. 

 The total amount of ammonia produced by what is distinguished as the 

 catalytic force of the earth used, averaged 139 gr. A small amount, but 

 relatively large when coniparing the ammonia of the atmosphere to that in 

 rain water. The result explains the good effect of airy drainage, plowing 

 and fallowing ; the formation of nitrates in the soil ; cultivation without 

 manure, and the presence of nitrogen in plants growing in artificial soil, 

 deprived of nitrogenized matter and watered with pure water. It also 

 shows how natural causes, winds, rains, temperature and pressure of the 

 air, assist in bringing about more rapidly the contact of air and soil which 

 results in the production of ammonia. 



Slow Oxidation. 



Schonbein has lately given to the public new facts in proof of the exist- 

 ence of oxygen in two opposite states of chemical polarity, and that in 

 cases of slow oxidation the ozonized atom and the autozonized atom act 

 simultaneously. For instance; in the slow oxidation of lead the oxygen is 

 halved and as much is taken up by the metal as by the water. He finds 

 the best amalgam to employ in order to get the greatest amount of the 

 peroxide of hydrogen is composed of 200 parts of mercury to one part of 

 lead. Rich amalgams give too little of the peroxide. The water used 



