THE NITRIc AvID OF THE SOIL. 271 
Nitric Acid as Food to Plants.—Experiments demon- 
strating that nitric acid is capable of perfectly supplying 
Sih vegetation with 
SS Pee nitrogen were 
= f a first made by 
aa UNG Boussingaul t 
! oe (Agronomie, 
Mt _ Chimie Agri- 
cole, etc., 1, 210). 
_ We give an ac- 
count of some 
of these. 
Two seeds of 
adwarfSunflow- 
er (L7elianthus 
argophyllus), 
were planted in 
each of three 
pots, the soil of 
which, consist- 
ing of a mixture 
of brick - dust 
and sand, as well 
as the pots them- 
selves, had been 
thoroughly 
freed from all ni- 
trogenous com- 
pounds by igni- 
tion and wash- 
ing with distill- 
Fig. 9. ed water. To 
the soil of the pot A, fig. 9, nothing was added save the 
two seeds, and distilled water, with which all the plants 
were watered from time to time. With the soil of pot 
C, were incorporated small quantities of phosphate of lime, 
yy AY 
NAN 
NG WN 
NEW 
S 
\ 
r IA 
WS Waiting 
WANE 
\\\ VN \ 
ANY Ri 
Qn \\) A) 
