CHEMISTRY OF HORTICULTURE. 
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air ; Condorcet, vital air ; Lavoisier — consistently with the principles of the French 
nomenclature — gave it the title of oxygen. This term was obtained from the Greek noun, 
oxus, acid, and the verb gennao or genein, to generate, of which gen is a contraction. 
Chemistry, as an inductive science, was then in its infancy ; but, under the guidance and 
industry of the great men of that period, it made surprising advances. Lavoisier consi- 
dered oxygen to be the sole cause of acidity; and as by direct and incontrovertible evidence 
it was proved that numerous .substances were converted to acids by being united with 
oxygen gas, he was so far justified in his theory. Eecent discoveries have equally proved 
that acid properties are not wholly dependent upon oxygen, since it is known that the 
muriatic among several other acids contains no oxygen whatever. Nevertheless, so far as 
knowledge of chemical affinities then extended, Lavoisier was justified in his opinion, 
and to this day the name of oxygen is retained. 
It will now be essential to appeal to the best authorities we possess, in order to put 
the student in possession of the opinions generally entertained by philosophers of this 
surprising agent ; after the citation of which it may be useful to extend our theoretical 
views, especially as a vast unexplored field appears open to legitimate inquiry. 
Oxygen is more abundantly diffused throughout nature than any of the other 
elementary bodies : it forms eight-ninths of the weight of water; about one-fifth of the 
weight of the atmosphere, and a large relative proportion of the earthy and mineral bodies 
which form the solid matter of the globe. 
The properties of oxygen-gas most immediately noticeable are these : It is devoid of 
colour, taste, and odour; and being transparent, it is likewise invisible; “ It possesses the 
mechanical qualities of atmospheric air, and therefore can be compressed or expanded by 
heat and rarefaction ; It is heavier than common air, for 100 cubic inches, at a mean 
temperature and pressure, weigh 34-^-ths grains, whereas an equal volume of atmo- 
spheric air weighs 31 grains ; It is but slightly soluble in water, that is, to the extent of 
one twenty-seventh part of that fluid in volume.” 
Oxygen gas, we have seen, was at one time called vital air, and indeed it can be 
respired ; but vitality could not be long sustained under its stimulus. All the vital 
functions of the lungs would, for a time, be highly and most fatally excited ; and life 
would be destroyed as by a process of spontaneous combustion. More will suggest itself 
on this very important fact when we arrive at the consideration of atmospheric air ; it 
will suffice now, in proof of the fact, to state that a most remarkable property of the gas, 
and that on account of which it was called Jire air, is the rapidity and splendour with 
which iron wire, steel filings, charcoal, &c., previously ignited, burn in it. The intensity 
of the light emitted by burning phosphorus in oxygen gas, is barely tolerable. A light 
of still greater intensity can be excited by means of the oxyhydrogen blow-pipe, when a 
stream of each of these water-forming gases is made to meet on a small piece of lime. 
The experiment is one of extreme delicacy and considerable risk; but, if skilfully 
performed, exhibits the most magnificent display of elementary illumination that can 
possibly be conceived. 
When powerfully compressed, by a piston forced suddenly upon it in a glass tube, 
oxygen appears for a moment to become luminous. M. Thenard, however, believed that 
this luminosity was connected with the presence of some oily or fatty matter, heated by the 
sudden compression ; but this — if the previous phenomenon be of constant occurrence — 
must be little better than conjecture ; and indeed, atmospheric air, diluted as it is bv a 
preponderance of azotic gas, produces a luminous flash when forcibly and suddenly 
compressed. If then the simple fact be worthy of credit, we may register it among many 
others, as among the evidences which may be adduced in support of the electrical theory 
which it will be the object of these articles to advocate. 
Professor Brande, when treating on the properties of oxygen, says, “ that in all cases 
of combustion in oxygen, the combustible and the oxygen combine, and the product con- 
sequently manifests an increase of weight proportionate to the quantity of oxygen with 
which it has united.” Thus combustion is not a process of destruction, but of the combi- 
nation of two or more bodies, the product of which always exceeds in weight that of the 
