ON SOLUTION OF CITRATE OF MAGNESIA. 
215 
parently ceased about the fifth day, occupying then about half 
the height of the bottle. The contents of the bottle were thrown 
on a filter, washed with water and dried. The dry precipitate 
weighed 120 grains. The washings, which were neutral, were 
then evaporated to dryness, and yielded a white residue, weighing 
25 grains. Twenty grains of the precipitate, after ignition 
in a platina crucible, left a residue ot 2.88 grains of mag- 
nesia. 
Twenty grains of the same precipitate were dissolved in half an 
ounce of water by aid of a sufficient quantity of muriatic acid ; 
ammonia was then carefully added, until the acidity of the solution 
was neutralized, and afterwards a solution of chloride of calcium was 
dropped in until it ceased to cause a precipitate. This, when col- 
lected, washed, dried and weighed, amounted to fifteen grains of ci- 
trate of lime, equivalent to 9.61 grains of citric acid. The precipitate 
which forms in a neutral solution of citrate of magnesia is there- 
fore composed of 3MgO, Ci,+ 14HO. 
Thirty grains of a deposit in an ordinary bottle of citrate of 
magnesia, after being washed and dried left, after ignition, 5.8 grs. 
of magnesia. 
Twenty grains of anhydrous magnesia were dissolved in a solu- 
tion of 100 grains of citric acid in 700 grs. of water, and after 
standing two weeks, no precipitation occurred. 
Twenty-two and- a-half grains of the same magnesia were dis- 
solved in the same bulk of solution of citric acid. At the expira- 
tion of a week precipitation commenced, but ceased after it had 
accumulated to one fifteenth of the bulk of the solution. 
The conclusions deduced from these experiments are : 1st, That 
the neutral salt, 3MgO,Ci, though at first very soluble, has a ten- 
dency to assume the crystalline state, and will separate from 
its solution although it may be mixed with a portion of the acid 
citrate. 
2d, That the salt 2MgO, HO, +Ci, will keep a longer time 
without precipitating, and in proportion as the quantity of magne- 
sia is increased above two equivalents, the tendency to precipita- 
tion increases. 
3d. It would also appear, when the process of precipitation is once 
established in the solution by the separation of the tribasic salt, that 
under certain circumstances that salt continues to be formed and 
