ATMOSPHERIC AIR AS THE FOOD OF PLANTS. v7 
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, \xxi, 282), that in the burning of a mixture of 
“oxygen and hydrogen gases in the air, the resulting water 
‘contains smmonia. 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. 
Bence Jones (Phil. Trans., 1851, ii, 399) discovered ni- 
tric (nitrous?) acid in the water resulting from the burh- 
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, Ixxxiv, 215) have more recently confirm- 
ed the result of Jones, but because they could detect 
neither 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 conbastion: 
Meissner (Untersuchungen tiber den Sauerstoff, 1863, p. 
283) was unable to satisfy himself that either nitrous ack 
or ammonia is generated in combustion. 
Finally, Zabelin (Ann. Chem. u. Ph., cxxx, 54) in a 
series of careful experiments, found that when alcohol, il- 
luminating gas, and hydrogen, burn in the air, nitrous acid 
and ammonia are very frequently, but not always, formed, 
