ATMOSPHERIC AIR AS THE FOOD OF PLANTS. 77 
slowly than that which is produced by lightning, must 
really oxidize much more nitrogen to nitric acid than the 
latter, because its action never ceases. 
Formation of Nitrogen Compounds in the Atmosphere, 
—b. From free nitrogen (by ozone?) in the processes of ,) 
combustion and slow oxidation. 
At high temperatures.—Saussure first observed (Ann. 
de Chimie, 1xxi, 282), that in the burning of a mixture of 
oxygen and hydrogen gases in the air, the resulting water 
contains »mmonia. He had previously noticed that nitric 
acid and nitrous acid are formed in the same process. 
Kolbe (Ann. Chem. u. Pharm., cxix, 176) found that 
when a jet of burning hydrogen was passed into the neck 
of an open bottle containing oxygen, reddish-yellow va- 
pors of nitrous acid or nitric peroxide were copiously pro- 
duced on atmospheric air becoming mingled with the 
burning gases. 
Bone Jones (Phil. Trans., 1851, il, 399) discovered ni- 
tric (nitrous ?) acid in the ie oe from the burn- 
ing of alcohol, hydrogen, coal, wax, and purified coal-gas. 
By the use of the iodide-of-potassium-starch test (Price’s 
test), Boettger (Jour. fiir Prakt. Chem., \xxxv, 396) and 
Schénbein (ibid., lxxxiv, 215) have more recently confirm- 
-ed the result of Jones, but because they could detect 
neitlier free acid nor free alkali by the ordinary test-pa- 
pers, they concluded that nitrous acid and ammonia are 
simultancously formed, that, in fact, nitrite of ammonia 
is generated in all cases of rapid combustion. 
Meissner ( Untersuchungen tiber den Sauerstoff, 1863, p. 
283) was unable to satisfy himself that either nitrous acid 
or ammonia is generated in combustion. 
Finally, Zabelin (Ann. Chem. u. Ph., xxx, 54) in a 
series of careful experiments, found that when alcohol, il- 
luminating gas, and hydrogen, burn in the air, nitrous said 
and ammonia are very frequently, but not always, formed. 
