DISSERTATION ON THE ATMOSPHERE. 261 
The local nature of coal-beds seems to show that variety of 
climate prevailed formerly, as now. During the primary 
era we may also suppose temperature to have varied, and 
with it the power to produce carbonated limestones. 
But in addition to carbonic aeid, ammonia must have been 
present in primordial air. The aluminous and ferruginous 
matter affords proof of it. Some years ago Dr. Faraday 
exposed white clay, that had been heated to redness, to the 
atmosphere for one week. After the lapse of which time it 
was found to contain ammonia in appreciable quantity, 
which it evolved on the application of heat. In this case 
the immediate source of the ammonia in the clay, was in- 
disputably the air. Now, precisely the same proof may be 
drawn from primary earths as to the existence of ammonia in 
coeval air. 
The alumina, or clay, of primary days, liberates ammonia 
under precisely the same conditions as Faraday’s clay did, 
and further, moistened mica-schist emits a characteristic 
ammoniacal smell. These statements claim for ammonia a 
primordial place in atmospheric air, and suggest an inorganic 
origin from its elements. 
Dr. Charles Daubeny doubts this, but admits an inorganic 
origin. Sagacious doubts may arise from inability to com- 
prehend such peculiar unions as that of nitrogen and hydro- 
gen happening on the earth’s surface ; but we are apt to 
contract our view by forming too low an estimate of the part 
which matter may play in such reactions. More especially 
is this the case when we recall the true marvels of chemical 
power that have been shown to be inherent in earth and 
porous media. Moreover, moistened iron-filings, at ordinary 
temperatures, in contact with free nitrogen or atmospheric 
air, induce, according to Austin and others, the formation of 
ammonia. Saussure also maintained that the free nitrogen 
of the air contributes to the ammonia of the same. Mulder’s 
experiments also go far to substantiate this opinion. Some 
interesting researches of Schonbein also strongly support 
this opinion. To chemists it has long, indeed, been familiar 
that minuteness of division in certain bodies, as in platinum, 
enabled them to induce combination in elements otherwise 
most averse to union. Schonbein shows this property to 
belong, in various degrees, to all substances. 
However much the above reasoning may be questioned, it 
can scarcely be doubted that electric influence would gene- 
rate large supplies of nitrogen compounds in the air during 
the mighty convulsions that throbbed in the bosom of young 
nature. 
