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 atmosphere during 86 days but 24 
milligrams of nitrogen. The crop, supplied with nitrate 
of potash, weighed 200 times as much as the seed, and 
assimilated 66 t:mes as much nitrogen as was acquired by 
A and C from external sources. 
2. That nitric acid of itself may furnish ad/ the nitrogen 
requisite to a normal vegetation. 
In another series of experiments (Agronomie, etc., I, pp. 
227-233) Boussingault prepared four pots, each containing 
145 grams (about 5 oz. avoirdupois) of calcined sand 
with a little phosphate 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. 38; 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. 
ea er ed eee $3 |S8s [SS3s_ 
Sg S ara = = 2g ,j@a. s 
2). 2 bee = San a © | 8Sss |$es~ 
> ae a : a wdso SSN SSS 
S z Se, > a S+ SRxe |e wele~=s 
Ss = Ss LE SS SS & Sos RD 
Ba a Ss 83 8 SS | SSe | S88 lSS eee 
= S xs | S82 [S888 rs SES 
S| os zs S& S | 288 | SES |SESs Sakae 
| grms. grms. grms.,. grms. | grms. corms. anme grms. 
— a —_——_—— — —_—— 
1..! 0.0033 | 0.0000 | 0.0033 | 0.0053 | 0.0020+ | 0.397 1 1 
2..| 0.0033 | 0.0033 | 0.0066 | 0.0063 | 0.0002 | 0.720 1.8 2 
3..' 0.0033 | 0.0066 | 0.0099 | 0.0097 | 0.0002t | 1.130 2.8 3 
4..| 0.0038 | 0.0264 | 0.0297 | 0.0251 0.0046¢ | 3.280 8.5 9 
* N=Nitrogen. 
In the first Exp. a trifling quantity of nitrogen was 
gathered (as ammonia?) from the air. In the others, and 
especially in the last, nitrate of soda remained in the soil, 
12* 
