116 
REPORT ON SOLUBLE CITRATE OF MAGNESIA. 
Equivalent portions of the crystallized acid reduced to pow- 
der, and calcined magnesia, were thoroughly triturated together, 
moistened with water into a paste, and heat applied until the com- 
bination ceased, and it was nearly dry. In this way a neutral ci- 
trate may be prepared, by mixing about 34 parts of magnesia with 
100 parts of citric acid, adding enough water to make the mixture 
pasty, and drying immediately in the evaporating dish over the 
fire, constantly stirring. This method, with the observance of cer- 
tain precautions which will be indicated by experience, will pro- 
bably be found most convenient in practice. In our experiments, 
however, though sometimes succeeding, it frequently failed. "When 
the water is added to the mixed powders heat is generated, and fre- 
quently the water appeared to combine immediately with a portion 
of the powder, which became hard and lumpy, making it impos- 
sible to moisten the whole of it, without adding considerable 
additional water; when this occurred, the resulting citrate was al- 
ways more or less insoluble. 
One difficulty in the preparation of the soluble salt is the neces- 
sity of properly regulating the heat; as a water bath heat is insuf- 
ficient, recourse must he had to a direct application of heat, or to 
a sand bath, in either of which the heat is liable to be too high, 
and without great care will decompose the citric acid, and spoil 
the salt. Neither is it desirable to prolong the application of heat 
to the acid after it is fused, before adding the magnesia, as it then 
loses a portion of its water of crystallization. Care should be 
taken to remove the mass from the fire before it is in any degree 
decomposed, and yet it should be so dry as to pass in a few minutes 
into a hard and rather brittle condition. 
A specimen is herewith presented of citric acid deprived of its 
water of crystallization, which we prepared by the long continued 
application of a carefully regulated heat to the crystallized acid. 
There is great danger of decomposition in this process. 
The acid thus prepared is a nearly white amorphous pulverulent 
soluble substance, supposed to possess the chemical affinities of 
of the acid in an increased degree. It was mixed with an equiva- 
lent portion of magnesia and thrown into water with a view to the 
formation of the salt extemporaneously, but without success. A 
specimen of this mixture is presented. 
