PHARMACOPffilA OF BOiTAL COLLEGE OF PHYSICIANS. 321 
In fact, we do not hesitate to assert, that the chemical pro- 
cesses given in this Pharmacopoeia are, in the first place, use- 
less and uncalled for; in the second, neither calculated in 
many instances to obtain the cheapest or purest products. To 
prove our first position, it can easily be understood, that the 
persons engaged in chemical operations are either well-in- 
formed chemists, having recourse to the best authorities, and 
so independent of the Pharmacopoeia; or ignorant persons 
without books, for whom the directions of the Pharmacopoeia 
are quite insufiicient. Let us take the preparation of nitrate 
of silver, as an example. You are desired to take 
"An ounce and a half of silver; half an ounce of nitric 
acid; two ounces of distilled water. Mix the nitric acid with 
the water, and dissolve the silver in these in a sand bath; then 
increase the heat by degrees, and let the nitrate of silver be 
dried; liquify this in a crucible, by a gentle fire, till the water 
being expelled, the ebullition shall have ceased: then pour 
immediately into proper moulds." 
Now all this, as far as it goes, is very correct; but no igno- 
rant person could prepare a saleable article by such directions. 
Our friend, Mr. Ferguson, the late chemist at Apothecaries' 
Hall, could show the London College a great many omissions 
in their details. We have often seen the numerous precau- 
tions taken by this gentleman, and he has kindly permitted 
us to tell them. The pure silver of the jewellers is the kind 
he employs. It contains gold and some copper: by dissolving 
in dilute nitric acid, perfectly free from chlorine, the gold is 
thrown down as a blackish powder. It is better always to 
crystallize the nitrate of silver; and if it be necessary to filter 
the solution, let it be through pounded glass, for the slightest 
contact of organic matter will blacken the salt. The crystals 
should be placed in a glass funnel and washed with a stream 
of distilled water, which will carry all the nitrate of copper 
to the bottom of the funnel, so that if you reject a drachm or 
two of the salt in the neck, you will separate all the copper. 
The crystals must be then completely dried, and melted in a 
platinum crucible; if melted cautiously, there is no necessity for 
