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GARDENING AS A SCIENCE. 
No. IX. 
It having been proved that atmospheric air consists of two gases (airs), 
possessing very opposite and distinct qualities, we must turn our attention to each 
of those gases, individually. The nature of the union by which they are held 
together in order to constitute the air we breathe, is suspected to be that of simple 
mixture ; it may be so, though we find it difficult to suppose that it is not effected 
by some powerful attraction. Without, however, dwelling upon a phenomenon 
which defies complete elucidation, we shall endeavour to investigate the nature 
of azote. 
Azote^ or, as it is now generally termed, nitrogen^ from being the base of nitrous 
acid, was first pronounced a distinct air, or gas, by Dr. Rutherford in 1792, who 
called it mephitic air. By Dr. Priestley it was submitted subsequently to minute 
examination. Its general qualities are thus described by Professor Brande : — " it is 
a colourless gas, with neither smell nor taste, having no action upon vegetable 
colours or upon lime-water ; neither is it absorbed by water, except that fluid has 
been deprived of its ordinary portion of air by long boiling, when it takes up about 
one and a half per cent. Its refractive power in regard to light, is to that of 
atmospheric air, as 1'0340 to 1*0000. It is rather lighter than atmospheric air, 
compared with which, its specific gravity is 0*976. It is contained in almost 
every form of animal matter : in the strictest sense of the word, azote is a non- 
supporter of combustion, for all burning bodies are immediately and perfectly 
extinguished by it, and its electro-chemical relations are still obscure." 
The reader is now in possession of pretty nearly all that is known of its abstract 
quality, for so far as concerns the inquiries that have been entered into as to its 
simple or compound nature, they are of no moment whatsoever, being utterly 
vague and inconclusive. 
All that is essential to our present object, is this. If, so far as our knowledge 
extends, azote is found to be entirely incapable of decomposition, and it be claimed 
that whatever cannot be analysed or decomposed is elementary^ then we must 
admit that azote is an element. But if we perceive that when it enters into com- 
bination with other bodies or substances it manifestly assumes a liquid or solid 
form, we may be permitted to hesitate in our opinion. Thus, azote by union with 
hydrogen produces ammonia, which exists either as a gas, a liquid, or a solid salt. 
Again, with carbon and iron, it constitutes the dry, pulverulent substance which 
we call Prussian blue. 
Now we claim, that any substance whatever which can assume a variety of 
forms and conditions, must be, to a greater or less extent compound ; for to enable 
VOL. IX. NO. CV. D D 
