THE NITRIC ACID OF THE SOIL. 



273 



in abundance. Observe that in exps. A and C the crop 

 attained but 4 to 5 times greater weight than the seed, 

 and gathered from the atmospliere during 86 days but 2^ 

 milligrams of nitrogen. The crop, supplied with nitrate 

 of potasli, weighed 200 times as much as the seed, and 

 assimilated 6G times as much nitrogen as was acq;iired by 

 A and C from external sources. 



2. That nitric acid of itself may furnish all the nitrogen 

 requisite to a normal vegetation. 



In another series of experiments (Ar/ronomie, etc., I, pp. 

 227-233) Boussingault prepared four pots, each containing 

 145 grams (about 5 oz. avoirdupois) of calcined sand 

 with a little pliosphate of lime and ashes of stable-dung, 

 and planted in each two Sunflower seeds. To three of 

 the pots he added weighed quantities of nitrate of soda — ■ 

 to No. 3 twice as much as to No. 2, and to No. 4 three 

 times as much as to No. 3 ; No. 1 received no nitrate. 

 The seeds germinated duly, and the plants, sheltered from 

 rain and dew, but fully exposed to air, and watered with 

 water exempt from ammonia, grew for 50 days. In the 

 subjoined Table is a summary of the results. 



N=Nitrogen. 



In the first Exp. a trifling quantity of nitrogen Avas 

 gathered (as air.monia?) from the air. In the others, and 

 especially in the last, nitrate of soda remained in the soil, 

 12* 



