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SELECTED ARTICLES. 
three prices: 2s., 3s. 6d., and 4s. 6d. a pound. The retailer 
ordered the article of the second quality. This drug is 
subject to a certain variety, because it is not a regular and 
definite compound, but a mere mixture of rectified spirit and 
nitric ether. Certain differences must exist, according as it 
is prepared by the process of the Edinburgh, the London, or 
the Dublin Pharmacopoeias. But it need scarcely be said that 
no such differences will account for so extravagant a variety 
of price, as that mentioned by Mr. Cooper, and that the two 
inferior qualities of the drug must have been adulterated, 
probably with rectified spirit, or the cheaper addition of water. 
4. A most important set of adulterations are those practised 
upon substances of very great energy, and which are given in 
minute doses. For here it is not merely a fraud that the pub- 
lic must submit to; life itself may in consequence be brought 
into danger. Of this, hydrocyanic acid is an excellent ex- 
ample. The profession are generally aware of the extreme 
uncertainty of the strength of this formidable medicine. The 
fact has been often brought experimentally under my notice; 
but I prefer at present to quote some recent observations made 
by Dr. Fyfe, and presented by him in a report to the com- 
mittee on adulterations appointed by the College of Surgeons. 
Few medicines perhaps are subject to so many sources of 
variation as hydrocyanic acid. It is prepared by different 
processes, which are calculated to yield it of various strengths. 
Variations arise even where the same process is followed, ac- 
cording as the rapidity of the distillation varies, or the tem- 
perature of the refrigerator. It loses some of its acid unless 
carefully preserved. And a further diminution invariably 
occurs in the shop of the druggist, as the contents of a bottle 
are gradually dispensed. For one, or another, or all of these 
reasons, the proportion of real acid differs exceedingly. 
Among samples obtained in shops of great respectability, Dr. 
Fyfe found some that contained four times as much as others. 
Serious accidents might in consequence ensue in medical 
practice. This medicine is variable in its effects in different 
