280 ON THE DIFFERENT KINDS OF MAGNESIA, ETC. 
pears to me to combine all the desirable conditions, that 
which especially, is most convenient for preparing purga- 
tive draughts of magnesia, well lies, and very homogeneous, 
is that formed of four parts of oxide of magnesium, and one 
part of water. This hydrate will, therefore, be designated 
under the name of magnesia hydrated to one-fifth, as mag- 
nesia slaked with one-fifth. 
The hydrate of magnesia of which I speak is, I repeat, 
best suited for the preparation of the medicine of magnesia; 
and, as in this respect, I give it an exclusive preference over 
all other varieties of calcined magnesia. The following is 
rny formula for this kind of medicine: — 
Medicine of Magnesia , or White Medicine. 
|& Magnesia hydrated to l-5th, 8 
This medicine should be taken at one dose in the morn- 
ing, fasting, and immediately after its administration half a 
glass of cold water should be drunk, but not more, experi- 
ence having taught me that taking too much liquid weakens 
its purgative action, which is owing to a portion of the 
magnesia passing the pylorus, and, consequently, escaping 
the solvent action of the acids of the gastric juice and the 
lactic acids, produced by the stomachal digestion of the 
sugar. 
The medicine of magnesia prepared according to my for- 
mula, is more active than that obtained by the following, 
the formula which M. Gobley has proposed to substitute 
for it, as I have ascertained by chemical experiments, which 
is, doubtless, owing to the latter containing an infinitely 
smaller quantity of sugar. 
These effects of the medicine of magnesia are constant ; 
it is only in a few subjects enfeebled, and incapable of sup- 
porting any nourishment, that I have known it necessary ; 
it is the purgative of people who digest. This purgative 
Sugar syrup, 
Orange flower water. 
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