458 
PHARMACEUTICAL MEETING. 
occasion to examine various samples of the “ fluid magnesia of pharmacy. 
The results are embodied in the accompanying table. The analyses are now 
brought under notice, by way of aiding the present discussion respecting the 
proposed strength of liquor magnesiae carbonatis of the next .British ±har- 
m The^fficial “ Solution of Carbonate of Magnesia ” is a solution of the salt 
in distilled water, charged with carbonic acid gas. It is stated to contain 
“about 13 grains of carbonate of magnesia in a fluid ounce. ±5y carbo¬ 
nate of magnesia” is evidently intended the ordinary article ol the 
shops, a hydrous mixture of true carbonate and hydrate of magnesium 
(3 MgC0 3 , Mg2 HO, 4H 2 0). The strength of the Pharmacopoeia solution 
is given also in terms of oxide of magnesium, or magnesia (MgO) ; thus, A 
fluid ounce of it, evaporated to dryness, yields a white solid residue, which, 
after being calcined, weighs not less than 5 grains.” _ If the solution contain 
13 grains of “ carbonate ” per ounce, the calcined residue will weigh 5 2 grams. 
Speaking exactly, we may say that the official liquor, if of full strength, 
contains, in 1 fluid ounce, 19 grains, or not less than 17^ grains, of pureAn¬ 
hydrous carbonate of magnesium (MgCO a , 3H 2 0)—for this is the salt which 
crystallizes from the solution by spontaneous evaporation at any ordinary 
temperature. . „ a 
The table shows the strength of seven different specimens ot fluid mag¬ 
nesia.” They were ordinary trade samples, selected so as to represent the 
products of the six chief makers of this preparation. The amount ot salt 
dissolved, the amount deposited in crystals in the bottle or jar, and the total 
amount per fluid ounce, before any deposition occurred, is given or eac 
sample. This information is repeated in three forms ; the first indicates the 
number of grains of oxide of magnesium yielded by 1 fluid ounce ; the 
second gives the amount of official “ carbonate of magnesia, from which 1 
fluid ounce was prepared; the third shows how many grains of crystalline 
carbonate of magnesium are contained in 1 fluid ounce. Taking the centre 
columns we see, that if much more than 9 grains of “ carbonate of magnesia 
be dissolved in one ounce, a portion of the salt will be deposited, sooner or 
later, and the medicine thereby be weakened. Specimen No. 3 had also lost 
a portion of its salt by crystallization, but this was probably due to insuffi¬ 
cient treatment with carbonic acid in the first instance, for the bottle was we 
corked. 
The analyses indicate that if liquor magnesise carbonatis be made by dis¬ 
solving 8 grains of “ carbonate of magnesia" in 1 fluid ounce of water (by 
aid of "carbonic acid), the product may be expected to be stable. . A stronger 
solution is liable to become w r eak by deposition of crystals within the con¬ 
taining vessel. 
The Chairman said this subject was one well worthy of consideration, but 
in his opinion it was just one of those preparations, like effervescing carbonade 
of soda, which might very well have been omitted from the Pharmacopoeia. 
Although it was desirable that a standard should be fixed, it was not a,t all 
likely that pharmaceutists in general would prepare it, as they were not likely 
to have the convenience for it, and therefore it must be left in the hands of 
skilled manufacturers. If they could settle the most desirable strength, it 
might be left in their hands. There was a gentleman present who manufac¬ 
tured it on a large scale, and perhaps he could give them his opinion with re¬ 
spect to it. ...... ,, 
Mr. Carteighe (of Messrs. Dinneford and Co.) was of opinion that the 
alteration proposed by Professor Redwood in the formula for fluid magnesia 
