ON THE PURIFICATION OF BISMUTH. 
3? 
impurity ; so far I agree with the B. P. definitionCommercial bismuth” 
... “it is generally impure.” 
That copper is found in most specimens of commercial bismuth has been 
known some time. Parrish, in his 4 Practical Pharmacy, 1 1859, says, “ It (bis¬ 
muth) generally contains both arsenic and copper,” and Draper, in his ‘ Review 
of the Dublin Exhibition,’ asks the question, “ Why is it so difficult to obtain 
bismuth free from copper?” (Pharm. Journ. Aug. 1865, p. 56.) I purified (?) 
my specimens by the B. P. process, but copper still remained even when fa¬ 
voured with an extra dose of nitre-fusion. 
The fault I find with the B. P. process is, that a test recognizes copper as a 
possible impurity, and one not to remain in the purified metal, but the process of 
purification given is incapable of removing it. 
I do not think it necessary in a Pharmacopoeia to require absolute chemical 
purity in all its preparations; but when substances are poisonous or alter the 
physical characters of the preparations, they should be removed and an officinal 
process should correspond with its published tests. 
The precipitation of the nitric solution of bismuth by water separates bis¬ 
muth from copper, silver, iron, etc., but recent experiments of Dr. Guming 
show' that arsenic is thrown down in the precipitation. Dr. Guming recom¬ 
mends diluting the nitric solution of bismuth with sufficient water to cause a 
slight precipitate; this precipitate, he says, is arsenico-nitrate of bismuth, which 
is less soluble than the basic nitrate of bismuth. When the solution is clear, 
decant and finish the precipitation with water in the usual way. There is here 
a v/aste of bismuth in two ways, first, precipitated w r ith the arsenic, and, se¬ 
condly, still dissolved in water as bismuth pernitrate. Dr. Guming purifies the 
first from arsenic by boiling in liq. sodse, but leaves the second unnoticed {vide 
4 Chemical News,’ May 29, 1868). 
Would not precipitating the nitric solution by carbonate of ammonia, wash¬ 
ing the precipitate with liq. ammonia), and reduction, be an easier and more 
economical plan ? 
X am Sir, yours, etc., 
G. Brownen. 
NOTE ON METALLIC BISMUTH, AND LIQUOR BISMUTH! 
ET AMMONITE CITRATIS. 
BY DR. REDWOOD. 
The vicissitudes which have attended the commerce of bismuth for several 
years past have produced an unfavourable influence on the condition, in regard 
to purity, of some of the preparations of bismuth which are used in medicine. 
The price of the metal has undergone great fluctuations, ranging from 2s. 6d. 
to more than 20 s. a pound; and, although the highest prices to which it has 
thus attained have been unprecedented in its previous history, the proportion 
of impure bismuth in the market has, at the same time, been unusually large. 
This unsatisfactory state of things appears to have arisen from a falling off 
in the supply of bismuth from those localities whence the best samples have 
been obtained, while new sources of supply, especially the Australian, have 
yielded the metal in a state in which its purification has been attended with 
considerable difficulty. Of the impurities most commonly occurring, arsenic, 
lead, copper, and silver are the most important. The bismuth may be freed from 
the first two of these, if present, with comparative ease, by a simple metallurgical 
operation which consists in fusing it with nitre, as directed in the Pharma¬ 
copoeia. This is the process usually adopted, and which answers best for re- 
