ON DIFFERENT KINDS OF MAGNESIA, ETC. 
273 
and therapeutical observations concerning the varieties of 
oxide of magnesium found in pharmacy, which I now make 
public. 
The following is the formula in question: — 
Bruise the magnesia carefully with a little syrup, and, 
when the mixture is perfectly homogeneous, add the re- 
mainder of the syrup and the orange-flower water. 
Four months after the publication of this formula, M. 
Gobley, our colleague, was led to prove a chemical phe- 
nomena with which I was partially acquainted, but to 
which chemists had not called attention, namely, the pro- 
perty which recently calcined, that is to say, anhydrous, 
magnesia possesses of remaining liquid when in contact with 
a certain quantity of water, and of afterwards becoming, in 
the hydrated state, solid after 24 hours' contact. 
The consistence which the potions had acquired was due 
to the solidification of the water by the magnesia, or rather 
to the hydralation of the magnesia. 
However, I would observe that the two magnesian po- 
tions which have served for the text of M. Gobley's pub- 
lication, had been prescribed with a smaller quantity of sy- 
rup than that I have indicated in my formula, which ren- 
dered their solidification more easy and more prompt. This 
fact was, moreover, proved by the author. 
Although, says he, in this potion the magnesia is in con- 
tact with only six parts of water, there was no solidification 
in 24 hours; this is owing to the large proportion of sugar 
in the mixture. Indeed, if we diminish the syrup, and re- 
place it by an equal quantity of water, the mixture solidifies 
in 24 hours. 
From this, M. Gobley concludes that it will be necessary 
Medicine of Magnesia. 
J$ — Calcined magnesia, 
Simple syrup, 
Orange-flower water, 
8 
80 
20 
