1816.] during the Year 1815. Dy 
far from intimate. Why should the supporters of combustion not 
have the property of uniting with each other? It has been long 
known that the simple combustibles have that property. Sulphur 
unites to copper with such violence as to produce both light and 
heat in abundance ; yet nobody on that account has thought proper 
to class sulphur among the supporters of combustion. Neither is it a 
sufficient reason to class chlorine and iodine along with sulphur, 
that all the three unite with hydrogen and form an acid. 
The only exclusive privilege which remains to oxygen is, that it 
alone, or its compounds, are fit for the respiration of animals, and 
necessary indeed to preserve life. The breathing of the other sup- 
porters of combustion is almost instantly fatal to animal life. © 4 
2. Chlorine is now pretty generally admitted to be a simple sup- 
porter of combustion. Almost the only chemist of eminence who 
adheres to the old opinion is Berzelius, His opposition is founded 
on the supposed inconsistency of Davy’s theory with the chemical 
canons, which he has established by a vast number of uncommonly 
accurate analyses. But this inconsistency, | am persuaded, he 
will find on a closer examination to vanish entirely. If this were 
the proper place, I think I could show that the doctrine of Davy 
and the canons of Berzelius agree perfectly with each other. 
In Schweigger’s Journal for May 1815 (vol. xiii. p. 72) there is 
a long paper by Professor Hildebrandt, stating several objections to 
Davy’s theory of chlorine. I was extremely surprised on reading 
this paper to find that all the objections it contained had been 
examined and answered long ago, and that all of them were 
founded on mistakes. Chlorine, he says, converts nitrous gas into 
nitric acid, and therefore it must contain oxygen. This was the 
first experiment that I tried when Davy published his theory. I 
found that the change here stated actually took place; but on 
examining my chlorine it was mixed with common air; and upon 
preparing pure chlorine I found that it produced no change on 
nitrous gas. Davy afterwards made the same experiment and pub- 
lished it, and the fact is now well known to all chemists of pre- 
cision. Another objection is, that when common salt is decomposed 
by the galvanic battery the chlorine appears at the positive wire. 
This, so far from being an objection, is a strong argument in favour 
of Davy’stheory. Oxygen and iodine are likewise attracted by the 
positive pole; so should chlorine, if it be a simple supporter of 
combustion. 
Another objection is that, when metals are burnt in chlorine gas, 
they are converted into oxides. The fact is not so, unless water be 
present in the vessel ; they are converted into ehlorides, a variety of 
which have been describew by Dr. John Davy. The other objec- 
tions of Hildebrant are all ef a similar nature, and do not appear 
to me to be worth mentioning, as they have all been refuted long 
ago. 
It is amusing to observe the efforts which the French chemists 
have made to deprive Davy of the honaur of this theory. There is 
