Combinations of different Metals and Chlorine. 181 
proportion of muriatic acid in the submuriat of copper is appa- 
rently half of that which exists in the muriat; hence, supposing 
the composition of the submuriat of tin to be similar, 100 of it 
will consist of 
70.4 gray oxide 
19.0 muriatic acid 
10 .6 water 
100.0 
Probability alone can be attached to this estimate. I have 
not given the calculations by which it was made, as their data 
are liable to objection. 
3. On the Combinations of Iron and Chlorine. 
As there are two oxides of iron, so there are also two dis- 
tinct combinations of this metal and chlorine. One may be 
directly formed by the combustion of iron wire in chlorine 
gas ; it is that volatile compound described by Sir Humphry 
Davy in his last Bakerian Lecture, which condenses after 
sublimation in the form of small brilliant iridescent plates. 
The other, I find, may be procured by heating to redness, in 
a glass tube with a very small orifice, the residue which is 
obtained by evaporating to dryness the green muriat of iron ; 
it is a fixed substance requiring a red heat for its fusion ; it is 
of a grayish but variegated colour, of a metallic splendour, 
and of a lamellar texture. As it absorbs chlorine when heated 
in this gas, and becomes entirely converted into the volatile 
compound, and as the volatile compound may likewise be 
obtained by heating in a glass tube nearly closed, the residue 
from the evaporation of the red muriat, it is evident that the 
