Dr. Thomson on Oxalic Acid . 
73 
But for practical purposes, it is more convenient to consider 
the acid as a constant quantity. The following table is con- 
structed upon that plan. 
Acid. 
Base. 
Weight of 
Salt. 
Oxalate of Ammonia 
IOO 
34.12 
134.12 
— Magnesia 
100 
3571 
135-71 
— Soda 
100 
. 57- 1 4 
157-14 
*- Lime - 
100 
bo. 00 160.00 
— - Potash 
IOO 
122.86 
222.86 
Strontian 
IOO 
I 251-51 
— — Barytes 
IOO 
142.86 242.86 
9. In the preceding statement, no account has been taken 
of the water of crystallization which might still remain at- 
tached to the salts, notwithstanding the heat to which they 
were exposed. There is reason to believe, however, that in 
most of them this water must be so small, that it may be over- 
looked without any great error. Oxalates of soda and of 
ammonia, I have reason to believe, lose all their water of 
crystallization at a moderate heat. This is the case also with 
oxalates of lime and barytes, and I presume that the oxalates 
of strontian and magnesia are not exceptions ; but oxalate of 
potash retains its water much more obstinately. I believe 
that in that salt the weight of acid and of base are nearly 
equal, and that when dried in the temperature of 212 0 , it still 
retains nearly 10 per cent, of water ; but I have not been able 
to establish this opinion by direct experiment. 
The composition of oxalate of strontian in the preceding 
table, was so different from what 1 expected, that I repeated 
MDCCCVIII. L 
