248 On definite Proportions: 
by any difect experiment related in these Essays to form a cotiz 
clusion respecting crystallized minerals, there is however no 
doubt of its validity; for why should marble, fluor spar, and pon- 
derous spar, be formed according to a law which is not ap- 
plicable to other minerals? Such a diversity is scarcely con<- 
eelyable. |. 
On the other hand; the application of the rule will obtain for 
mineralogy a degree of mathematical certainty, and afford to. 
chemists, who are engaged in the analysis of minerals; a ready 
mode of satisfying themselves; how far their operations are cor- 
rect ; while, without some such means, these analyses can never 
be brought te a sufficient degree of accuracy. It is true that, 
aecording to this view of the subject, the greater number of such 
analyses, eve when performed by the greatest, masters, can only 
be considered as approximations, which in many eases searcely 
come at all near to the truth; but such is the ordinary course of 
human labours: Since Bergmain’s analyses of salts, which were 
so masterly for his time; 30 years are scartély elapsed, and yet 
many of them can at present hardly even be called approxima- 
tions. And the numerical determinations of the proportions of 
mixture of various substances, which I have attempted to obtain 
with the greatest care, and with the utmost possible accuracy, 
and which I have inserted in this Essay, will certainly not be 
sufficient for the future ; and it will be possible; with the assist- 
ance of the laws here developed, to correct them, and to bring 
them nearer to the truth. But I am confident that our succes- 
sors will pardon the imperfections of my experiments; as it must 
be allowed that chemistry, in its present state of advancement, 
must still bée grateful for the valuable labours of Klaproth, Vau- 
quelin, and others, although most of their analyses are become 
insufficient for its putposes of progressive investigation. 
4, 
Lastly, when several combustible substances, which we cons 
sider as simple, unite with each other, the proportions, in which 
these combinations are possible, are determined by their capacity 
for oxygen, the combinations taking place in such a manner, thats 
if they were oxidated in a certain degree, the oxygen taken up by 
one of the substances, would lea multiple by 1, 2,3... of the 
quantity taken up by the other. ‘Thus sulphur; phosphorus, and 
arsenic, unite with metals in such proportions, that a salt may 
be produced by the oxygenization of the compound, or at least 
would be produced according to the general rule, 
The same is also true of other metallic compounds, which are 
separated from mixtures in a state of fusion, by chemical causes, 
- such as erystallization or heat: for instance, of crystallized amal+ 
gams, 
2 
