455 
ON LIQUOR MAGNESI2E CARBONATIS. 
BY C. UMNEY, F.C.S. 
At the last meeting of this Society, its members were invited by the Presi¬ 
dent to discuss certain amendments then proposed by Professor Redwood, to be 
made to various processes and formulae of the British Pharmacopoeia, prior to 
the publication of the next edition. 
It must have been most gratifying to those present, to have received the 
thanks of their Professor, on behalf of himself and the Medical Council, for the 
great help which he acknowledged had been rendered to them when compiling 
the Pharmacopoeia, not only by individual members of the Society, but by the 
results of the discussions that have from time to time taken place within these 
walls. 
In commencing this evening’s discussion, it is undoubtedly out of order not 
to take the subjects as they were enumerated, and as they appear in the present 
Journal; as some of these, however, have been previously discussed, it will be 
excusable to depart from the accustomed rule, and take a subject which, to my 
knowledge, has been little commented upon here. 
In making various experiments, in connection with the manufacture of Liq. 
Magnesia Carbonatis , shortly after its introduction into the Pharmacopoeia, I 
was induced to examine the fluid magnesias of pharmacy, of professedly B. P. 
strength ; the results obtained showed that the strongest were about two-thirds, 
and the weakest but one-third the strength, of the officinal solution. 
On a large scale, I found, I could with ease produce a solution that would, 
when filtered, and with carbonic acid in excess, retain an equivalent of at least 
5 grains of calcined magnesia in the fluid ounce, the minimum quantity indicated 
by the British Pharmacopoeia in its “ characters and tests” for Liq. Magn. Carb., 
a quantity which would have been expressed with more accurate comparison, 
when stating the equivalent of carbonate present, as nearly 12 grains (11’93) 
instead of 13 grains in the fluid ounce. 
But with this solution I found, unless the greatest precautions were taken to 
ensure considerable excess of carbonic acid, being retained in the vessels in which 
it was stored, and that even under slight pressure, considerable quantities of the 
terhydrous carbonate of magDesia would always be precipitated. The determina¬ 
tion to strictly adhere to the Pharmacopoeia, I must confess in this case, resulted 
in disappointment and often vexation, for after the magnesia solution had been 
supplied to pharmacists but a short time, complaints reached me that the fluid 
was so nauseous that children refused to take it, and that it would not keep as 
well as the solution supplied on former occasions before the formula was given 
in the Pharmacopoeia. 
The substance of the explanation generally offered was, that the compilers of 
the Pharmacopoeia, in their wish to make a preparation of almost the greatest 
saturation, in order to increase its activity, had exceeded the strength at which 
such solution could advantageously be presented as a commercial article ; and 
to its excessive strength alone was the nauseous taste, and its liability to deterio¬ 
ration due, and not to a defect in manufacture. 
The suggestion therefore of Professor Redwood, that the solution should be 
decreased in strength to 10 grs. carbonate to 1 fl. oz. will, I am sure, be gladly 
received by the manufacturer and pharmacist, and doubtless most willingly 
adopted by the profession. 
It is to be feared, however, that this strength will rarely be attained in com¬ 
merce, if one may give an opinion from the solutions of town and country manu¬ 
facturers obtained in December last (a table of which I have appended), for, 
with the high standard of the present Pharmacopoeia, but half of these ap- 
