THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS 
[March 18,1871 
741 
together till the colour of the iodine has disappeared; 
the solution is then filtered into a clean iron dish, 
and rapidly evaporated till a drop removed on the 
end of an iron wire solidifies on cooling. It is then 
poured out upon a porcelain dish, and, when solid, 
broken up and put into a bottle. 
Ferrous iodide forms a greenish solution, which 
gives the usual reaction of ferrous salts with red 
prussiate of potash, resulting in the formation of a 
deep blue precipitate. 
3FeI 2 -f K 6 Fe 2 Cy I2 
= 6KI -{- Fe f, 3 Fe 2 Cy l2 . 
Iodide of iron is a deliquescent substance and 
soon absorbs oxygen from the air, giving a brown 
mixture of iodine and a ferric hydrate-iodide, which 
is insoluble in water. In tliis state, particularly if 
it shows signs of containing uncombined iodine, it is 
unfit for use in medicine, but should be digested 
with water and iron wire, and when the brown colour 
of the liquid has disappeared, filtered, and once more 
evaporated to dryness. 
The syrup is an important preparation. In 
making it, it is essential to follow closely the in¬ 
structions of the Pharmacopoeia and to employ the 
purest sugar. 
BISMUTHI SUBCARBONAS. 
BY T. P. BLUNT. 
It may not be generally known that the commer¬ 
cial “ subcarbonate of bismuth” (Bismutlii Carb. 
P. B.) contains an appreciable quantity of silver, in 
the form of chloride. 
I have been in the habit for some time of prepar¬ 
ing liq. bismutlii by the solution of the above salt in 
nitric acid, and though samples from various sources 
have been used, there has always appeared a heavy 
and very finely divided sediment, which passed with 
readiness through a filter, and could only be removed 
by subsidence and decantation; as this proved a source 
of some annoyance, I determined to ascertain the 
nature of the insoluble matter, when it was found as 
above stated, to consist of chloride of silver. 
The amount was ascertained as follows:— 
1000 grains of the subcarbonate of bismuth were 
dissolved in nitric acid, the sediment allowed to sub¬ 
side, and the supernatant fluid decanted off as closely 
as possible, the residue was washed with nitric acid 
by decantation, and a large excess of strong am¬ 
monia was then gradually added, the precipitated 
oxide of bismuth was thrown on a filter and re¬ 
peatedly washed with ammonia water. 
To the filtrate a slight excess of nitric acid was 
added, the precipitate collected on a filter in the 
usual way, dried, ignited in a porcelain capsule, 
treated with nitro-liydrocliloric acid, and again gently 
ignited; it weighed 13 grains, representing 0’98 
grain metallic silver, or about 0T per cent. This 
proportion is obviously of no importance from a the¬ 
rapeutic point of view; it might, however, be worth 
while for large makers to separate it in the course of 
manufacture, as might readily be done by some such 
process as that given above, without any loss of 
bismuth. 
THE PRECIPITATION OF QUINIA BY 
IODIDE OF POTASSIUM FROM ACID 
SOLUTIONS.* 
BY J. M. MAISCH. 
Some time ago the following prescription was 
received:— 
fb Quinise Sulpliatis gr. xv 
Potassi Iodidi 5 i 
Tinct. Ferri Chloridi 5i 
Aquoe $iv 
Syrupi Zingib. 51 . 
M. 
The quinia salt was dissolved in the tincture of 
iron, the potassium iodide in the •water, and the so¬ 
lutions mixed; a brown precipitate was at once 
formed. The quinia salt was now dissolved in the 
water with the addition of a little dilute sulphuric 
acid, the iodide added, and after solution had taken 
place, the tincture of iron; the same result was pro¬ 
duced. 
It was now supposed that the iodide might contain 
some iodate, that on the addition of an acid, iodine 
was liberated, which, with the excess of iodide, •would 
form biniodide of potassium, and that the precipita¬ 
tion occurred in consequence of the presence of tliis 
compound. But when the solution of the iodide 
(Atkinson and Biggar’s) was acidulated with muri¬ 
atic acid, a reddish colour was not produced, nor 
would starch paste brought in contact with the liquid 
acquire a blue colour ; iodic acid was therefore not 
present. 
Righini stated ( Journal cle Chim. Med. vol. xiii. p. 
110) that bisulphate of quinia produces with iodide 
of potassium a red pulverulent precipitate. 
A considerable quantity of iodide of potassium -was 
dissolved in a solution of one part of sulphate of 
quinia in twenty of water, the solution of the latter 
salt having been effected with just enough dilute 
sulphuric acid. A white precipitate was the result, 
doubtless owing to the presence of some quinidia in 
the quinia salt; for a solution of one part of quinia 
sulphate in forty of water, effected until a sufficient 
quantity of sulphuric acid, remained clear 011 the ad¬ 
dition of iodide of potassium in substance. When a 
considerable excess of pure sulphuric or muriatic 
acid was used for dissolving the quinia, the addition 
of solution of potassium iodide occasioned 110 turbidity 
or sediment; therefore the observation of Righini is 
not correct as far as it relates to neutral potassium 
iodide. 
A solution of sulphate of quinia (T40) with just 
sufficient acid was prepared, iodide of potassium 
added, and then solution of citrate of iron; a white 
turbidity with the gradual production of a bright red 
precipitate was the result. 
The same quinia solution was made, except that a 
considerable excess of dilute sulphuric acid was used; 
after the solution of iodide of potassium had been 
effected, every drop of the solution of iron citrate 
occasioned a brownish-wliite precipitate, which ra¬ 
pidly changed through various shades into deep 
brown. If the order of mixing was reversed, the 
potassium iodide yielded with dilute sulphuric acid 
a colourless solution, which became turbid and turned 
brown with the iron citrate, and now yielded with 
* Read before the Philadelphia College of Pharmacy, at 
the Pharmaceutical Meeting, Dec. 20, 1870. 
