50 
PROFESSOR GRAHAM ON THE CONSTITUTION OF 
5. Oxalate of Barytes. 
Ba CC H. 
This oxalate differs from all the preceding 1 , and contains only one atom of water. 
It was formed by digesting an excess of oxalic acid upon carbonate of barytes, and 
afterwards washing the resulting oxalate with cold water. 20 , 60 grains of the oxa- 
late, calcined by a low red heat, left 16*45 grains carbonate of barytes, equivalent to 
12*77 barytes. Hence it follows that the oxalate consisted of 
Composition of Ba CC H. 
Barytes 100 100 
Volatile matter .... 6! *32 59*08 
161*32 159*08 
Before being washed this oxalate had a sour taste, and the volatile portion of it 
amounted to 67*01 parts instead of 61*32; but it was evidently the neutral oxalate 
with a little free oxalic acid. It was not a binoxalate ; nor did such a salt present 
itself on digesting the neutral oxalate in oxalic acid, so that I am constrained to 
deny the existence of a binoxalate of barytes. Indeed it is scarcely a matter of doubt 
that no supersalt whatever exists of barytes, strontian, lime, or of the magnesian class 
of oxides. 
6. Oxalate of Potash. 
K CC H. 
Oxalate of potash is known to crystallize from solution with one atom of water, 
and with no other proportion. The crystals speedily become white and opake at 
212° Fahr., from the loss of water, but cannot, I believe, be made quite anhydrous 
at that temperature ; at least a portion of the salt, which had been exposed to 212° 
for four days, still retained water, consisting of 100 oxalate of potash and 3*4 water, 
which is rather less than a third of the water which the salt originally contained 
(10*8 parts). The oxalate of potash becomes quite anhydrous when dried at 300°. 
Of salt so dried 100 parts reabsorbed 10*63 water in a damp atmosphere with the 
greatest avidity. The oxalate of potash has therefore a certain attraction for a single 
atom of water, and this is an important feature of the salt. 
7. Binoxalate of Potash. 
K CC + H CC H 2 . 
This salt has hitherto been supposed to contain only two, but it certainly contains 
three atoms of water. 
21*37 grains of the salt, calcined by a full red heat, which is necessary for complete 
