196 
BRITISH PHARMACEUTICAL CONFERENCE. 
Acid. Citric. . . . 
Sugar.4- 
Magnes. Sulph. . . 0- 
Sodse Bisulpli. Cryst. 
Acid. Sulph. . . . 
Ess. Limonis. . . c 
On the Mode of Preparation. 
The ingredients are mixed in the usual manner by sifting, and thrown on 
to a hot metal plate to a depth of not more than half an inch. In a few mi¬ 
nutes the mixture becomes spongy, -when it is worked about and turned over 
with a scoop or other convenient instrument, to prevent any particles be¬ 
coming too dry.. 
In a minute or two more (this is the most delicate part of the operation, but 
impossible to describe on paper) it should be thrown on a cold slab, and put 
through a sieve of 4-6 meshes per inch, again heated and sifted through a 
rather finer sieve, the dust separated, and finally heated till desiccation is 
complete. It is well to watch it at first,- to see that the newly-made 
granules do not adhere to each other; but during the latter part of the final 
drying this is unnecessary. 
The metal plate may be of tin, enamelled iron, zinc, or tin, and I know all 
these are used, and very likely copper may do, but I have never heard of its 
use on the large scale. I would recommend zinc,, from its cheapness; 
plates that have been in nearly constant use for two years are but slightly 
bulged,—the original cost being 39s., thus showing a great advantage over 
tin, and I know of nothing against it. En passant, a manufacturer with whom 
1 was acquainted dried his preparation in a warm closet on skins of white 
leather, but the reason I know not. 
The modus operandi above described may not be universal, but I have found 
it answer well, and seen it employed by other parties. It is best to sift the 
dust out before the article is dry, as the dust then works in well with the next 
batch. A batch should not be more than 30 lbs. to be well attended to, and 
the loss in making is from 10 to 12 per cent. 
In conclusion, I must just refer to Sodse Citro-tart., B. P. If this article 
is introduced on its own merits, I have nothing to say about it; but if as a 
substitute for granular citrate of magnesia, it is a decided failure, because it 
is too alkaline, and contains no sugar. 
Birmingham , August, 1868. 
The President agreed with those who condemned the use of the term “ Citrate of 
Magnesia ” for such a compound as was now sold under that designation. On the Con¬ 
tinent this name was applied to a true citrate of magnesia that was sold in the shops. 
Mr. Groves said that the dose of the true citrate of magnesia was very large, being 
about two ounces. 
8 oz. 
8 oz. 
4 oz. 
1- s- 
fl. 
SENNA. 
BY THOMAS B. GROVES', F.C.S. 
What I bhve to say about this interesting article of Materia Medica will be 
confined to its chemical history, ancient and modern, and will include an 
account of some attempts I have recently made to set at rest disputes as to the 
nature and properties of its active principle. 
