OXALATES, NITRATES, PHOSPHATES, SULPHATES, AND CHLORIDES. 
49 
of the salt contains (P2656 magnesia. A salt constituted with two atoms of water 
should contain CP2759 magnesia, of which the specimen analysed falls a little short, 
probably from containing some hygrometric moisture. 
The oxalate of manganese lost nothing at 212°, and was found by analysis to contain 
0 - 2416 water, which approaches very closely the quantity equivalent to two atoms, 
namely, 02474 water in one hydrated oxalate of manganese. 
In regard to several other oxalates of this class, namely, the oxalate of the prot- 
oxide of iron, of oxide of nickel, of oxide of cobalt, and of oxide of copper, I believe 
it is impossible to obtain them in a state of sufficient purity for analysis. They appear 
to cany down with them portions of the precipitating salts ; and they alter mani- 
festly in appearance and composition during the progress of the washing, to which 
they must be submitted for the purpose of purification. In the case of oxalate of 
copper, which was examined most particularly, the results were so anomalous that 
no inference whatever could be drawn from them. 
It will appear, however, that a neutral oxalate of copper with two atoms of water 
can exist but in combination with oxalate of potash, or with oxalate of ammonia, as 
a double salt. 
None of the oxalates of the magnesian class of oxides is more soluble in oxalic 
acid than in water, and none of them combines with that acid to form a binoxalate. 
The crystals, which are obtained on mixing together solutions of binoxalate of potash 
and sulphate of magnesia, and which have been supposed to be a binoxalate of mag- 
nesia, are really a mixture of oxalate of magnesia and of quadroxalate of potash. 
Hence there is no combination of oxalate of magnesia with oxalate of water ; which 
illustrates the fact that bodies of the same class, such as these two oxalates are, have 
no disposition to enter into union and form a new compound. 
4. Oxalate of Lime. 
Ca CC H 2 . 
The oxalate of lime contains two atoms of water, like the oxalate of magnesia, but 
parts with its water more freely than that salt. Thus 12’06 grains of the hydrated 
oxalate of lime were found to lose 1*6 grain of water at 212° Fahr. in the course of 
two days, T68 grain in three days, T84 grain in six days, and nothing more in nine 
days. The salt originally consisted of 100 oxalate of lime united to 27'85 water, of 
which last it has lost 19‘53 parts, and retained 8'32 at 212°. It is probable therefore 
that the constitution of hydrated oxalate of lime is the same as that of hydrated oxa- 
late of magnesia, that oxalate of lime forms only one definite hydrate, containing two 
atoms of water, but that it parts with the whole of its constitutional water at a mo- 
derate temperature. 
MDCCCXXXVII. 
H 
