METALLIC OXIDES. 
first, a su’phuret, which was decomposed at a temperature Oxides 
sufficient to melt it, so that the melted mass consisted of a satu- 
rated sulphuret of tin*. 
The undermentioned experiment, in which the sulphuret of 
tin produced an almost equal quantity of oxide of tin at a max- 
imum, proves that the relation between the oxides and the sul- 
phuret of this metal, is precisely the same as that which I 
found long ago with regard to lead — that is to say, the sul- 
phuret of tin must be composed as follows • 
Tin ... . 79 - 6 100 000 
Sulphur . . 21 ‘4 27 234 
Proust, in a very interesting memoir, has endeavoured to 
prove, that aurum musivum is a combination of sulphur with 
the oxide of tin, but oxided to a degree which does not exist 
in any other case, and he has adopted his conclusion from the 
circumstance, that this preparation, decomposed by fire in a 
closed vessel, produces sulphur, sulphuret of tin, and sulphu- 
reous acid j and I myself have actually verified, that aurum 
musivum, prepared in the usual manner, always produces, on 
this occasion, a small quantity of sulphureous acid. I have 
very just reasons, however, to consider this sulphureous acid 
as the product of matters different from the composition of 
aurum musivum. 
Three grammes of sulphuret of tin, reduced to fine pow- 
der, and mixed with lj grammes of pure sulphur, were ex- 
posed to a cherry red heat in a little glass ball with a narrow 
neck, closed at the mouth by a piece of charcoal. The ball 
was half filled. When the excess of sulphur had passed off, 
I took it out of the fire. The three grammes now weighed 
3*33 grammes, and was converted into a greyish yellow mass, 
which, except the deep colour, had all the characters of aurum 
musivum, which, in consequence of the method of its prepa- 
ration, cannot contain oxigen. I considered it, at first, as in- 
complete aurum musivum, which, if heated more with sul- 
* I tried, before I found this method, several others, which answered 
my purpose very imperfectly. Amongst others, T made an amalgam of 
five parts of tin with one part of mercury. I then reduced them to 
powder, and mixed them with sulphur. This mixture I exposed to the 
fire in a glass phial. The combination was made instantaneously, 
and broke the phial with an explosion. 
M 2 phur. 
