ON CHEMISTRY. 
149 
it therefore lias been deprived of one of the essential qualities of pure 
atmospheric air; and that it has been so deprived, will be ascertained 
by another concomitant proof; for there will be an absorption of wa¬ 
ter as soon as the air within shall become somewhat cool. In other 
words, the external air, pressing by its incumbent weight upon the 
surface of the water in the dish, will force a portion of it into the bell- 
glass; and as therein, it will meet with diminished resistance, owing 
to the abstraction of the oxygen, the water will make its mark at a 
level above the one at which it stood at the commencement of the 
experiment. If both their levels were marked, and the total capacity 
of the bell-glass ascertained by filling it with water, a comparison 
might easily be made between the total bulk, and that of the air con - 
sumed. In experiments of the above nature, great accuracy, how¬ 
ever, must not be expected, but, they suffice to evince that a consider¬ 
able portion of the air has been abstracted. The Azot remaining, 
could not be breathed; it would be fatal to any small animal. Its 
nature, however, has for the present been sufficiently described; and 
with respect to the oxygen, I refer the horticultural reader to an ex¬ 
periment for its production more pleasing and germain to his profes¬ 
sion, which he will find by reperusing the three first paragraphs in 
page 8, of the article upon water. 
I shall have occasion to revert to this experiment again, as involv¬ 
ing phenomena connected with the agency of solar light. 
Azot is lighter than atmospheric air, and still more so than oxy¬ 
gen gas. 
The specific gravity of the last is about 1,1. That of azot about 
,983 decimal parts, taking atmospheric air as the standard of unity, 
or at 1,000. One hundred cubical inches of azotic gas, according 
to Henry’s table, weigh about 30,5 grains (30i). 
The foregoing chemical facts are not new; they are, or may be, 
familiarly known to every practical and reading chemist; I therefore 
lay claim to nothing approaching to discovery in all that I have as 
yet adverted to. But I do not write for chemists ; my object is to 
introduce the young gardener to the knowledge of a few leading 
principles, and thereby to rouse a spirit of inquiry, a love of reading, 
and above all, a determination to reason, reflect, and draw conclu¬ 
sions by his own mental powers, uninfluenced by servile deference 
to the dicta of authority. 
Chemists are nearly agreed in the proportions they assign to the 
two essential components of air, Azot and Oxygen; but they are at 
variance in respect to the volume o( other fluids which are found to 
exist in it. Carbonic acid is one of these fluids, and it is estimated 
