Combinations of different Metals and Chlorine. 1 93 
quarter of an hour, a substance like enamel in appearance, 
being semi-fused, and which appeared to be a mixture of mag- 
nesia and the true compound of magnesium and chlorine, for 
heated with water magnesia was separated, and a muriat of 
magnesia formed. 
5. On the Relation between the Proportion of Oxygene and Chlo- 
rine in Combination with several Metals. 
Errors being very common in chemical analyses, even in 
those conducted most skilfully and carefully, all possible means 
should be taken to discover them ; and no means, I think, pro- 
mise to be more effectual for this purpose, than the general 
analogy of definite proportions. From a great variety of facts, 
it appears that oxygene and chlorine combine with bodies in 
the ratio of 7.5 to 33.6. With 1 part by weight of hydro- 
gene, for example, 7.5 of oxygene unite to form water, and 
33.6 of chlorine unite with the same proportion to produce 
muriatic acid gas. To judge therefore of the accuracy of the 
analyses of the preceding combinations of the metals and 
chlorine, it is only necessary to compare them with the ana- 
lyses of the oxides of the same metals. If the two agree, there 
will be reason to consider them both correct, but should they 
disagree, there is equal reason for supposing one or both of 
them to be wrong. 
Thus, as the orange oxide of copper is analogous to cuprane 
and the brown oxide to cupranea, the oxygene and chlorine 
should be to each other in these compounds as 7.5 to 33.6. And 
from comparison of my analysis, with those of Mr. Chenevix 
and M. Proust, it appears, that in the two first, copper being 
as 6 o, the oxygene is to the chlorine as 7.79, instead of 7.5 to 
MDCCCXII. C c 
