ON METALLIC BISMUTH. 
397 
taining 2-9 per cent, of copper. I fused this for ten minutes with one-fifth its 
weight of nitre, and then analysed the product. I found it to contain only 1-51 
per cent. Consequently, nearly one-half the copper had in this case been re¬ 
moved. Nevertheless, I cannot deny that fusion with nitre fails to remove the 
last portions of copper, and is therefore useless as far as small perceutages of 
this impurity are concerned. 
Admitting this, it becomes important to know the exact amount of copper 
commonly present in the metallic bismuth of commerce. To ascertain this 
point, consequently, I have taken three commercial samples of metal, and have 
made quantitative determinations of the amount of copper in each. The ana¬ 
lysis was performed as follows :—One hundred grains of the metal were dis¬ 
solved in dilute nitric acid, and the solution evaporated until a pellicle formed. 
About an ounce of a saturated solution of sal ammoniac was then added, the 
mixture slightly warmed, and diluted to the bulk of thirty or forty ounces with 
cold water. All the bismuth was thus completely precipitated as insoluble oxy¬ 
chloride, leaving the copper, etc., in solution. After some hours’ repose, the 
liquor was filtered, and the precipitate washed. The filtrate was evaporated to 
about two ounces, and a slight excess of ammonia added. After filtration, the 
liquor was acidified and precipitated by sulphuretted hydrogen. The sulphide 
was collected, washed with dilute sulphide of sodium, and dissolved in aqua 
regia. The solution was evaporated to dryness. The copper in the residue was 
then estimated, by precipitation with zinc in a platinum dish and weighing as 
metal, after the manner recommended by Fresenius. 
The results obtained were as follows :— 
Sample No. 1 . . . . 0T2 per cent. 
„ No. 2 ... . 0-07 „ 
„ No. 3 . . . . 0-05 „ 
Liquor Bismuthi prepared from the worst of these would contain about 0-0048 
grain of copper in one fluid drachm ; that is to say, less than the r^oth part of 
a grain in a dose. Mr. W. L. Howie, # in a paper read before the Glasgow 
Chemists and Druggists’ Association, in October, 1866, stated that he found the 
quantity of copper present in different samples of bismuth to vary from 0 - 04 to 
0-1 per cent. My results are in close accord with this statement. 
The fact that the nitre fusion fails to remove the copper constantly present 
in commercial bismuth has been the chief argument employed against the 
Fharmacopoeia process for Liq. Bismuthi. When it is seen that the amount 
of copper in the metal need never exceed one part in a thousand, and 
will generally be much less, this objection, I think, loses much of its importance. 
The total impurities present in the doubly refined bismuth prepared and sup¬ 
plied for pharmaceutical and chemical purposes by Messrs. Johnson and Mat- 
they are stated by the refiners never to exceed 0-5 per cent., and frequently to 
amount to not more than 0-3 per cent. I venture to think that such metal 
would bear comparison, in point of purity, with a very large number of chemi¬ 
cal products now used in medicine. 
But although, at the present day, all commercial bismuth contains an appre¬ 
ciable percentage of impurities, that is so only because there is no demand for a 
purer metal. In 1865, three years ago, Messrs. Johnson and Matthey exhibited 
in Dublin a large quantity of chemically pure bismuth. This metal was also 
shown at the Paris Exhibition last year. It can be produced in any quantity 
when required, and its price at the present time is 40s. per lb., the present cost 
of the commercial metal of good quality being 19s., and that of the doubly- 
refined metal already referred to 22s. 6d. A sample of this bismuth was kindly 
lent to me by Messrs. Johnson and Matthey, and placed upon the table at the 
* Pliann. Journ. Yol. VIII. p. 407. 
