132 
CHEMISTRY OF HOETICULTURE. 
the pot to support the shoots as they grow, and also a liberal supply of water should be given 
to the roots. In autumn, when the wood is ripened, remove to a lower temperature, until 
the plant is required to produce its bloom. Any time from February to May remove it into 
an increased heat, and flowers will be produced in great abundance, the racemes issuing 
from the axil of every leaf in succession for several months. Cultivation is effected by 
cuttings of the half-ripened wood planted in pots of sand, and placed under a glass in heat." 
The generic name is given in honour of Arthur Henfrey, Esq., a distinguished 
botanist. 
CHEMISTRY OF HORTICULTURE. 
By John Towers, Esq. 
(Continued from Page 103.) 
must advance methodically, in order to obtain some consistent view of the nature 
and operation of agents. 
Assuming, as I have done, a position which I hope the student will bear in mind, 
that every phenomenon in Meteorology has its origin in the decomposition of the sun's 
rays, when three great elements are developed, the specific agency of which produces 
definite effects. Now I propose to enter upon the investigation of water, and for this 
particular reason ; namely, that its constitution is very simple, and its elements more 
readily determinable than those of any of the other great natural agents with which 
science has made us acquainted. 
One of the elements of solar light is, unquestionably, Electricity ; and by that element 
water has been most completely decomposed, its two elements distinctly and palpably 
liberated, and in proportions so exactly precise, as to enable a skilful operator to produce 
again, by recombination, the very same quantity of water as that from which the said 
elements had been obtained. 
Here we must pause for a while, in order to justify our pretension of rendering every 
chemical term familiar to the uninitiated. 
1st, Analysis and Decomposition, in chemical language, are terms which convey the 
same meaning ; the former is of Greek origin, and expresses the tearing to pieces of 
any substance not destructively, but so as to dissever and clearly reveal its component 
elements. 
2nd. As antagonist to the process of decomposition, Synthesis, a Greek word also, 
is employed to express the re-union of those principles which have been so separated. If 
water is exposed to the analytic energy of electricity, its elements are separated, and may 
be very easily collected and measured, when it will appear that they consist of two aerial 
fluids or gases, to which have been assigned the terms — hydrogen and oxygen. These 
words were introduced by the celebrated French chemists, who, near the close of the 
eighteenth century, framed the then new and illustrative chemical nomenclature. The 
former — hydrogen — was founded upon two Greek words, which, written in English letters, 
are iidor, water, and gennao, to generate or produce. I venture, however, to suggest that 
it would be more correct to invert the terms, and thus to consider water as the fountain 
and principal source of the gas hydrogen, which as Dr. Fownes correctly says, "is always 
obtained for experimental purposes, by the deoxidising of water, of which it forms the 
characteristic component." 
Oxygen, one of the most potent agents of nature, exists in pure water, in a state of 
electric union with hydrogen. It was first discovered by Dr. Priestley, on the 1st of 
August 1774, who gave it the name of dephlogisticated air. Three celebrated chemists 
had detected oxygen much about the same period, as will appear from the following 
passage taken from "Lavoisier's Elements of Chemistry :"-—" This species of air was 
discovered almost at the same time by Mr. Priestley, Mr. Scheele, and myself;" but the 
palm of priority has been accorded to our English philosopher, Scheele called it empyreal 
