1815.) On Iodine. 125 
ordinary only because it was in opposition toa manner of thinking 
fortified by long habit and by many good experiments. It was 
making a great step towards the knowledge of the real nature of 
oxymuriatic acid, to have questioned the received opinions respect- 
ing the nature of this acid: for it is much easier to find a new truth 
than to detect an old error. And we claim it as our own property, 
that we first perceived that oxymuriatic acid might be considered as a 
simple body. Davy, in adopting the conclusion which we had 
drawn from our experiments, has added nothing to its certainty ; 
but we must admit that he has illustrated it at great length, and by 
the influence of his great abilities, has contributed very much to 
propagate it. I ought to observe, however, that M. Dulong and 
M. Ampere had adopted it long before Davy, and that I myself 
had always stated it as the most probable opinion, in the courses of 
chemistry which I delivered at the Polytechnic School. At present 
the discovery of iodine appears to have fixed the opinion of the 
French chemists on the nature of oxymuriatic acid. I shall there- 
fore refrain from all discussion on the subject. 
Admitting then that oxymuriatic acid is a simple body, it be- 
comes in the first place necessary to introduce a modification into 
the proportions of the muriates. But as this does not follow imme- 
diately, from oxymuriatic acid being a simple substance, it may 
be necessary to justify it. Admitting a muriate to be a combina- 
tion of muriatic acid and an oxide, it is possible that the hydrogen 
of the acid and the oxygen of the oxide may not form water; but 
may yemain in the salt. I exposed in succession barytes, strontian, 
lime, and oxide of zinc, to the action of dry hydrochloric gas, in 
a glass tube, toa temperature approaching to a red heat, and I 
always obtained a great deal of water. To verify the same fact on 
potash, I put about a gramme of potassium in a platinum crucible, 
melted it, and plunged it into a glass vessel filled with hydrochloric 
gas. Whenthe combination appeared complete, I weighed the 
crucible exactly, and then poured water on the salt, which occa- 
sioned no effervescence. The salt beeng dried in a low temperature, 
was found not to have increased in weight, nor after being fused 
was it found to have lost any thing. We ought then to admit it as 
a certain fact, that the muriates are all changed into chlorurets 
when melted, or even dried, and some of them even by being 
erystallized. We may suppose, as we have done for the iodurets, 
that the chlorurets dissolve in water without undergoing decompo- 
sition, and that when we unite hydrochloric acid with an oxide, 
the hydrogen of the acid and the oxygen of the oxide form water.* 
Whether this be the case or not, nothing but chlorurets exist at a 
red heat. It is therefore of these compounds that it is necessary to 
determine the proportions. 
I have found (Mem. d’Arcueil, ii. 168) that 100 parts of silver 
take 7°6 of oxygen. Berzelius instead of that number gives 7°44, 
Though it be difficult to say which is most exact, I shal] adopt this 
* See Note A, 
