70 
THE CODEX AND THE BRITISH PHARMACOPEIA. 
water of crystallization as it is separated from the carbonate of soda upon the 
absorption of the carbonic acid gas, without disturbing the apparatus or the 
operation, another tube immediately below the diaphragm connects the vessel 
with the source of gas which is supplied through it to the soda. The vessel 
should have a lid with a socket adapted so as by means of a tube to convey any 
unabsorbed gas into a second vessel containing carbonate of soda. It is known 
that the whole of the carbonate has been converted into bicarbonate when the 
gas is no longer absorbed, and when the water begins to run from the crystals 
contained in the second vessel. In the P. B. the inconvenience arising from 
the water of the carbonate of soda is overcome by employing three parts of 
dried carbonate with two of undried, and mixing them thoroughly. By the 
Codex process there is apparently a saving of labour. 
CHAPTER XIV. 
PERMANGANATES. 
As I noticed before, in a similar case, this can scarcely be a chapter of per¬ 
manganates, as one only is introduced. 
121. Permanganate de Potasse. K0Md 3 0 7 = 158 3. 
Permanganas Potassicus. 
Potassic Permanganate. 
Binoxide of manganese . . . Forty grammes . . 40 
Chlorate of potash .... Thirty-five grammes 35 
Caustic potash.Fifty grammes . . 50 
Water.Q. S. 
Very dilute nitric acid.Q. S. 
These proportions are those of the P. B. There is not so much care shown as 
usual in the Codex directions; nitric acid is employed instead of sulphuric to 
neutralize the solution of permanganate of potash and potash, and altogether 
the directions, characters, and tests of the P. B. appear to be an improvement 
upon those of the Codex. 
CHAPTER XV. 
VEGETABLE ACIDS. 
Comprising crystallizable or glacial acetic acid, radical vinegar, distilled vine¬ 
gar, benzoic acid by sublimation, benzoic acid by the wet process, gallic, vale¬ 
rianic, lactic, and tannic acids. 
Acide Acetique. C 4 H 3 0 3 , H O = 60. 
122. Acide Acetique Cristallisable*. 
Acide Acetique Pur, Acidum Aceticum Purum. 
This acid is identical with the glacial acetic acid of the P. B., having a den¬ 
sity of 1*063, and is prepared by distilling dry acetate of soda with sulphuric 
acid. 
123. Vinaigre Radical. 
Acetum Radicale. 
Radical Vinegar. 
This acid is prepared from acetate of copper by distillation, and is represented 
as being very concentrated, but it is difficult to see the necessity for this acid, 
having already the previous one ; it is a very old method, and was in use three- 
quarters of a century ago. 
