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REPORT ON SOLUBLE CITRATE OF MAGNESIA. 
cess has been published for obtaining citrate of magnesia solid 
and perfectly soluble. We present one which is our own, and 
which is perfectly successful. It is very simple. 
Take of Crystallized Citric Acid, 100 parts. 
Calcined Magnesia, 29 " 
Water, 10 " 
Dissolve the acid with the water, then gradually add the magnesia; 
or better, omit the water, and on a sand bath melt the acid in its 
water of crystallization, and thoroughly incorporate the magnesia 
with it. In either case we obtain a mixture of a pasty consist- 
ence, which soons hardens, and may be pulverised for use. 
" The citrate thus prepared is neutral, and yet very soluble 
even in twice its weight of water. But from so concentrated a 
solution it soon precipitates as a hydrate, which is insoluble even 
in a large quantity of water. Dissolved in a certain quantity 
(say 8 or 10 times its weight) of water, its solution is permanent. 
We call it Citrate de Magnesia officinal.* 
" The 29 parts of oxide of magnesium may be replaced by 64 
parts of hydro carbonate of that base. In this case the reaction is 
accompanied by a disengagement of carbonic acid, and the pro- 
duct is light, porous, white, and has the aspect of bicarbonate of 
soda before being powdered. It is rather insipid; if an agreeable 
acidity is desired, the proportion of acid as above should be aug- 
mented 4 parts." 
Your Committee have prepared the salt by the above processes, 
and submit samples of it herewith. It will be remarked, that in- 
stead of being neutral and insipid as described they have a more 
or less acid taste, and a decided acid reaction with litmus. The 
solution which is made from it by a formula to be given presently, 
is about as acid as that usually sold in the shops and directed by 
the Pharmacopoeia. 
The formula does not agree exactly with the proportion gener- 
ally employed to form a solution of the neutral salt. Viewing citric 
acid as a tribasic acid, containing 1 equivalent of water of crystal- 
lization, (C 12 H 5 On, 3HO,) HO, its combining number would be 
201 ; while that of magnesia is 20 ; hence the salt (3MgO, Ci,) 
* The term officinal in French is equivalent to our word permanent or ready- 
made, as contradistinguished from extemporaneous. 
