66 
THE CODEX AND THE BRITISH PHARMACOPEIA. 
BY A. F. HASELDEN. 
{Continuedfrom p. 16.) 
CHAPTER VH. 
IODIDES. 
This chapter contains iodide of potassium, iodide of iron crystallized, iodide 
of lead, protoiodide of mercury, deutoiodide or biniodide of mercury, and iodide 
of sulphur. 
78. Iodube de Potassium*. KI = 166T. 
Ioduretum Potassicum. 
Iodide of Potassium. Potassic Iodide. 
Iodine.One hundred grammes, 100. 
Iron turnings or filings. . . Thirty grammes . . 30. 
Distilled water.Five hundred grammes, 500. 
Carbonate of potash ... A sufficiency. 
This is prepared by decomposing a solution of iodide of iron with carbonate 
of potash, in the same manner as formerly directed in the Pharm. Lond., 1836, and 
when made for small consumptions is preferred, as it possesses, according to 
some, the advantage of not forming iodate of potash, which is produced when 
prepared without the intervention of iron, and by the direct combination of 
iodine and potash, necessitating the fusing of the salt in a crucible, to convert 
the iodate into iodide. 
Iodide of iron, or ferrous iodide, is prepared as ordered in the P. B., only 
that less iron is ordered in the Codex, but there can be no advantage in that, 
as by exposing a larger surface of the iron, the iodine is more quickly converted 
into iodide and the process sooner completed. 
80. Iodide of lead, or plumbic iodide, was left out of the original P. B., 
but is now restored ; the formula for its preparation is that of the Codex, and 
as follows:— 
Nitrate of lead .... One hundred grammes, 100. 
Iodide of potassium . . „ „ 100. 
Dissolve the nitrate of lead, cold, in a sufficient quantity of water, and on 
the other hand prepare a saturated solution of iodide of potassium. Pour 
the solution of iodide of potassium cold, and by small quantities, into that of 
the nitrate of lead, until a yellow precipitate is no longer produced; wash the 
deposit of iodide of lead with cold distilled water and dry in a stove. 
81. The Protoiodide of Mercury, or hydrargyrous or mercurous iodide, 
green iodide of mercury of the P. B., and the deutoiodide of mercury, or hydrar- 
gyric or mercuric iodide, being the red iodide of mercury, are prepared by pro¬ 
cesses similar to our own. 
83. Iodide of Sulphur is a combination of ten parts of sublimed sulphur 
and forty parts of iodine. They are to be well rubbed in a glass or porcelain 
mortar until thoroughly mixed, then transferred to a flask placed upon a sand- 
bath, and at first gently heated, augmenting the heat when the colour of the 
upper portion of the mixture has gradually become deeper, so as it were to fuse 
the iodide ; all being melted, the flask should be inclined in different ways, so 
as to introduce into the mass the portions of iodine condensed in the upper 
sides, and, when cold, break the vessel, and keep the iodide in glass-stop¬ 
pered bottles. Iodide of sulphur was not in the P. B., but has now been intro¬ 
duced, seemingly taken from the Codex. These iodides are all interesting to 
