NOTES ON THE PHAllMACOP(EIA. 
517 
even tolerably abreast of the advance of knowledge in the present day. He 
heard gentlemen speak of certain chemical substances being impure, because 
they contained foreign matter, which, however, when reduced to a percentage, 
did not appear to be appreciated until it got into the second or third place of 
decimals. That was all very well as a matter of chemical research; at the 
same time it was a refinement and hypercriticism which, in the ordinary prac¬ 
tice of their business, they might very safely disregard. Dr. Redwood told 
them last month that they ought not to be contented with the tests which were 
supplied in the British Pharmacopoeia for the examination of various com- 
pouuds; that it was not desirable they should say such-and-such substances 
would do because they had passed the ordeal of pharmaceutical test, but that 
they were bound to find out for themselves, and to apply, tests with still 
greater rigour and delicacy. He thought they were drifting in the direction 
of over-refinemeut, which would certainly defeat its own purpose, and which 
could not possibly be carried out by the pharmaceutical chemists of this country. 
The vast majority of them must absolutely depend for their supply of chemical 
preparations upon the chemical manufacturer. If they got articles which were 
fairly and honestly what they professed to be, free from fraudulent admixture 
and wilful or careless adulteration, they must of necessity be content. There was 
no help for it, as it would be utterly impossible for any pharmaceutical chemist 
to prepare the whole of the chemical substances "which he used in his business. 
He had taken notes of one or two of the matters in the British Phar¬ 
macopoeia which seemed to him worthy of notice, not altogether by way of 
criticism, but upon which some interesting observations might be made. The 
first article to which he would refer was alum. The official alum was that 
which contained sulphate of ammonia. Until the issue of the British Pharma¬ 
copoeia, potash alum was the official article. Previous to 1864 or 1865 it was 
exceedingly difficult to meet with potash alum in commerce ; nearly the whole 
of the commercial alum was ammonia alum : and it was not a little singular 
/ O 
that about that time potash alum again made its appearance in commerce, and 
he had been several times supplied with it in the ordinary way commercialiy. 
He attributed that to the production of chloride of potassium from mineral 
sources, which had reduced the price of potash, and so enabled it to compete 
with ammonia. It w r as said in the Pharmacopoeia that the aqueous solution 
of alum should not acquire a blue colour from the addition of yellow or red 
prussiate of potash. Now he had never yet met with a specimen of commercial 
alum which would answer that test, and it was by no means an easy matter to 
get alum entirely free from iron. Referring to oxide of antimony, it was stated 
to be u a greyish-white powder.” Several specimens which he had found in 
commerce had been much more strongly coloured than this description would 
seem to justify. He believed that oxide of antimony, when quite pure, instead 
of being greyish, was quite white, and that the colour invariably depended upon 
the presence of iron. They could easily see how this got in. The black sulphide 
of antimony, he believed, invariably contained iron ; and if they went to work 
with chloride of antimony, that was still subject to contain iron. When the 
solution of chloride of antimony was poured into the distilled water, a portion 
of the iron was carried on mechanically with the oxide and chloride of anti¬ 
mony, and could not be removed by washing, and therefore was present in the 
final product. But there were several ways in which this might be got rid of. 
tie had succeeded pretty -well by washing the precipitated oxide and chloride of 
antimony with dilute hydrochloric acid for a considerable time. There was 
another thing with regard to the washing of the oxide. After it had been 
treated with carbonate of soda, and it was difficult to eliminate the last trace of 
chlorine, he had washed the oxide almost continuously for three days, and still 
there was presence of chlorine. The oxide of antimony was carried through 
