632 
LECTURES ON THE BRITISH PHARMACOPOEIA. 
Pharmacopoeia; it is much the same as the Edinburgh, but is of double the 
strength in squill as compared with that of the London. 
Podopiiylli Resina. —The resin of podophyllum is precipitated on pouring 
a concentrated tincture of the dried root into water acidulated with hydrochloric 
acid. I have been asked, “ What is the use of the hydrochloric acid ?” Its use is 
to precipitate hydrochlorate of berberia (not beberia), and was proposed by 
Maisch (Pharm. Journ. 2nd ser., vol. v. p. 183), who succeeded in preparing ber- 
berine—or berberia as we must now call it in conformity with Pharmacopoeial 
nomenclature—from podophyllum, its occurrence there having been previously 
pointed out by Mayer. It is probably an, if not the, active principle of podo¬ 
phyllum. 
Potassa Sulphurata is the old Potassii Sulpliuretum ; a name which Mus- 
kett (Pharm. Journ. 2nd ser., vol. i. p. 214) suggested should be altered, inas¬ 
much as it implied a composition which the preparation does not possess. The 
vague character of the new name is quite consistent with the character of the 
preparation. 
Potass as Bicarbonas. —The process and necessary apparatus for the pre¬ 
paration of this salt will be found described in greater detail in the ‘Pharma¬ 
ceutical Journal,’ vol. i. p. 274. 
Potassa: Permanganas. —In the laboratory we find Boettger’s process 
(Zeitschrift fiir Chem. und Pharm., Bot. 3, and Chemical News, vol. iv. 
p. 69) preferable to the one given in the Pharmacopoeia. Boettger’s process is as 
follows:—Fuse together in an iron crucible four parts of hydrate of potash and 
two parts of chlorate of potash, and when oxygen begins to be evolved, remove 
the crucible from the fire, and stir in gradually one part of peroxide of man¬ 
ganese. Heat again until the mixture solidifies, then boil it with eighty parts 
of water, and finally pass carbonic acid through the solution until it becomes red. 
The liquid is now decanted, filtered through gun-cotton, evaporated to one-half, 
and set aside to cool. Large crystals of the permanganate may be thus obtained. 
Potassa: Sulphas. —This unimportant salt is one of the many in the Phar¬ 
macopoeia, processes for the preparation of which are given, but which might 
well have been omitted altogether. If this is one of the processes introduced in 
order, according to Garrod (Med. Times and Gaz. 1864, vol. i. p. 359), to pro¬ 
pagate a certain amount of knowledge of chemistry among a large class, both of 
the medical profession and druggists, who look upon the Pharmacopoeia as a 
text-book, then it has failed in its object. For although in our laboratory, for 
example, we are rigid upholders of undeviating adherence to the Pharmacopoeia 
in all that relates to the galenical compounds, yet in sulphate of potash and 
many other chemical substances we adopt different and, as we think, better means 
of arriving at the desired end. We think with Garrod (ibicl.'), that the only point 
required to be secured in the manufacture of chemical substances is their purity 
or fitness for medicinal administration, and a complete set of tests for each 
article ensures this. 
To make sulphate of potash, we are directed to take of the residue of the 
process for nitric acid, one pound. This residue, you know, is bisulphate of 
potash. This is to be dissolved in water; then slacked lime, eight ounces, gra¬ 
dually added—directions to stir well, which is imperative, being omitted— 
until reddened litmus-paper, immersed in the mixture, is restored to a blue colour. 
We shall now have formed much sulphate of lime, the greater part of which 
will have been precipitated, but some will remain in solution ; we are therefore 
to filter the solution through calico, and, having heated it to the boiling point, 
to add carbonate of potash as long as there is any precipitate. We now have 
carbonate of lime precipitated, and are therefore to filter again. But our solu¬ 
tion of sulphate of potash thus obtained will be contaminated with carbonate 
of potash; we are therefore to add dilute sulphuric acid so as to produce a 
