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BRITISH PHARMACEUTICAL CONEERENCE. 
use, was compared witli the above, and yielded a precipitate of sulphide of 
iron, of about half the bulk. IN'o indication of lead was found in either. 
Potash Water. 
A sample of “ potash water ” from one of the best makers, having been 
objected to because it tasted of soda and not potash, was subjected to exami¬ 
nation, and it was found, contrary to my expectation, that the palate of the 
consumer had given a correct judgment of its merits. “ It was very good 
soda water, but contained no potash.” The high position of the makers sug¬ 
gested a mistake in the labelling rather than a fraud, but former experience 
indicates that such mistakes are not uncommon ; on referring to my notes, I 
find, in February, 1862, a hamper of “potash water” had been returned to 
us, the purchaser stating that “ it tasted so strong of lime.” On testing, it 
was found to contain only a trace of lime, but it was soda water instead of 
potash. 
Another sample, purchased from the same makers fa local firm of good 
standing), was found to contain both potash and soda; excess of tartaric acid 
and the addition of alcohol having yielded a precipitate which gave a strong 
soda flame, till washed with alcohol, when the potash flame became equally 
distinct. 
Spirit of Nitrous Ether. 
Several commercial samples of spirit of nitrous ether having been examined 
by the Pharmacopoeia tests and found wanting, further samples were obtained 
from two of the best makers, with the view of purchasing, if possible, a spirit 
of nitrous ether which would stand the Pharmacopoeia tests; but, like the 
others, they were not found to yield any film of nitrous ether after agitation 
with twice their bulk of a saturated solution of chloride of calcium. 
It is to be hoped the new edition of the Pharmacopoeia will give a process 
for this preparation which, with ordinary care, will yield a product answering 
to the tests the Editors may see fit to append. 
11, Grey Street, Newcastle. 
PvEPOPtT ON THE “ DPIEI) ALUM ” OF COMMERCE. 
BY MR. JOHN WATTS. 
The “ Alumen Exsiccatum ” of the British Pharmacopoeia, no longer pos¬ 
sessing the composition assigned to it in that work, and being of little practical 
use in medicine, seems by its presence to clog the way, and to fill a space 
which a more useful and well-assured remedy would better occupy. How¬ 
ever, in the opinion of some practitioners, “ burnt alum ” still holds its 
ground, and we frequently find, even now, lotions and collyria prescribed in 
which it forms the principal ingredient. To ascertain to some extent whether 
this opinion was well grounded, by examining into the composition and qua¬ 
lity of the commercial article, and to see also whether that article corre¬ 
sponded with the one ordered in the British Pharmacopoeia, the following 
analyses were undertaken. 
To prepare “ dried alum ” the Pharmacopoeia orders us to take pure potash 
alum, to ignite it till v^atery vapour ceases to be disengaged, and then to 
preserve the exsiccated residue. This seems all very plain, but unfortunately 
potash alum cannot in any way be obtained now as a commercial article; 
indeed I completely failed to procure a specimen to work upon, and was con¬ 
sequently obliged to prepare some specially by dissolving alumina in oil of 
vitriol, and adding an equivalent of potassic sulphate. 
