4G0 
PHARMACEUTICAL MEETING. 
was, it was run off, in the process he had referred to, into large pits, where it 
was'allowed to deposit; and, if any one liked to buy the waste product, of course 
they were able to do so. He certainly was of opinion that thirteen grains to 
the ounce was an unfortunate strength, for, though it was quite possible to make 
it even as high as eighteen or even twenty grains, there would be great difficulty 
in keeping it. They must bear in mind that fluid magnesia was a preparation 
taken largely by the public, and was not one which was always ordered in pre¬ 
scriptions with three or four ounces of water. Generally a bottle of it was or¬ 
dered to be taken ; and the public, when using such a preparation, did not think 
so much of the necessity of putting the cork tightly into the bottle, as a chemist 
would ; and therefore in every respect it was desirable, in his opinion, to have 
the standard strength not higher than ten grains to the fluid ounce. It could 
be made at that strength to keep very well the greater part of the year; but, as 
he had before stated, it required the greatest nicety, and then it was an almost 
unsolved problem whether it would keep during certain states of the atmosphere. 
Mr. Corder Clayton said be had made some experiments on this prepara¬ 
tion ; but with regard to what Mr. Carteighe had said about a by-product, he 
had made inquiries, and he could not find in any case—and he had been up 
and down through the kingdom a great deal—that the fluid magnesia came 
from Newcastle. The bulk of it seemed to come from Jenning s, of Cork, and 
having examined it, he must say that he found it as near as possible of the Phar¬ 
macopoeia strength. Almost the first specimen which he had made, he had made 
too strong, and his customer wrote back to say that when he ordered carbonate 
of magnesia, he meant it, and did not want a mixture of bicarbonate of potash 
and sulphate of magnesia, and he triumphantly pointed to a small quantity of 
sulphuric acid which there was in the solution. He had then examined several 
specimens of dry carbonate of magnesia, and he found they did contain traces of 
sulphuric acid in them, and, therefore, all the fluid magnesia made from them 
was not perfectly free from this acid. He should be glad to know from Professor 
Redwood whether it were possible to wash recently precipitated carbonate so 
thoroughly as to remove all trace of sulphuric acid. 
Professor Redwood said that not only in reference to that precipitate, but 
other precipitates obtained under similar circumstances, as, for instance, preci¬ 
pitated oxide of iron, he had repeatedly endeavoured to obtain them free from 
every trace of sulphuric acid, but he had not been able to do so. He was ra¬ 
ther disposed to think with the gentleman who had first spoken, some of the 
sulphuric acid was retained in the state of a basic insoluble compound, and that 
that accounted for the great difficulty, if not impossibility, which there was in 
washing out the whole of the sulphuric acid. 
Mr. Martindale (of University College Hospital) said he might add one re¬ 
mark with regard to the Linimentum Potcissii Iodidi cum Sapone. He believed 
the only improvement required in the Pharmacopceia process was that to the 
solution of iodide of potassium a small quantity of water should be added pre¬ 
vious to the mixture with the solution, and that they should be careful not to allow 
much evaporation of water. If there were much evaporation, it should be re¬ 
placed at the end of the process. If it were made in a bottle well corked, and 
the materials were mixed at equal temperatures, a semi-transparent jelly 
would be produced ; but if they mixed one hot and the other cold, the result 
would be an opaque jelly. He had noticed that if it were shaken, and it was 
allowed to become cool, you then got an opaque jelly which was quite natu¬ 
ral, because particles of air got mixed up with it, and that accounted in most 
cases for the opacity which was frequently found. He always used the white 
Castile soap of commerce, but he had been told it could be made from the ordi¬ 
nary white curd soap, and probably this would be so if precautions were taken 
as to mixing the ingredients when both were at about equal temperatures. 
