118 On definite Proportions in Chemical Affinity. 
pendix to the Second Part of his work, appealing to his own ex- 
periments and those of the most ealebeated chemists, that gases 
do not unite in, measures proportionate to their volume. 
After haying cited particular cramps that many of them do 
not unite in a according to any determinate proportion, he 
concludes, ‘‘ that gases in 2o instance combine in equal or exact 
measure.” This, Mr. Murray thinks, might be perhaps properly 
extended to the whole doctrine of definite proportions. 
Sir H, Davy, in his Elements of Chemical Philosophy, advances 
an immense number of proofs that the theory of definite pro- 
porticns is not founded upon hypot hetical reasoning. He, as is 
already observed, rejects the doctrine of atoms, and founds his 
calgulations on the result of actual experiment, By this, ong 
of the very great ebjections to Mr. Higgins’s and Mr. Dal ton’s 
theory is removed ; namely, thar qabstaieee uniting in one pro- 
pertion only form a binary compound, for we haye no grounds upon 
which we can form such an opinion in the language of Mr. Dal- 
ton; it is merely an assumption. He supports, contrary to what 
Mr. Dalton has said, the theory advanced by Gay- Lussac, re- 
specting the union of gases ; which he beautifully illustrates by 
the combinations that are formed by azote and oxygen, carbon 
and oxygen,&e. And Mr. J, Davy, in his paper published in the 
Philosophical Transactions, On the gaseous Compounds of Car- 
bonice Oxide aud Chlori ine, i as given some very decisive examples. 
He observes, ‘‘ the proportions in which bodies unite appear to be 
etermined by fixed laws, which are exemplified in a variety of 
instances, and particularly in the present compounds, Oxy gen 
corabiies with twice its volume of hydrogen, and twice its volume 
of carbonic oxide, to form watrand carbonic ‘acid; and with double 
its volume of chlorine to form euchlorine ; and chlorine reclpro- 
cally requires its own volume of hydrogen and its own volume of 
cafe oxide to form muriatic acid and the new gas.” 
Sir H. Davy in his work has noticed several of the experiments 
upon which Berthollet founded his views of affinity, and has 
pointed out the source of some errors. According to Berthollet’s 
views, precipitates could not be thrown down in a state of purity, 
but must retain a portion of the substance with which the pre- 
cipitate was previously combined: of this we have many examples 
to the contrary, as when one metal in solution is precipitated by 
nother; and in the precipitation of magnesia, &c. 
Sir H. Davy also observes, “‘ that there is no difficulty in re- 
conciling the doctrine of proportions with the influence of quan- 
tity. None of th :¢ experiments of M. Berthollet can be considered 
as strictly contrary to the doctrine, and some of the most im- 
portant results of this sagacious chemist afford its confirmation.” 
From the above quotations and observations, I think it will 
clearly 
