336 
THE BRITISH PHARMACOPOEIA. 
Aconitine is changed to “ Aconitia emetic tartar is called “ Antimonium 
tartaratu-m , Tartarated antimony black sulphuret of antimony is “ Antimo¬ 
nium sulphuratum , Sulphurated antimony nitrate of bismuth is “ Pismn- 
ilium album , White bismuth A Calx cl'ilorinata is now “ Calx chlorata, the En¬ 
glish chlorinated lime being retained; chloroformyl is changed to “ Chloro- 
for mum potassio-tartrate of iron is now “ Ferrum tartaratum , Tartarated 
iron white precipitate is “ Hydrargyrum ammoniatum, Ammoniated mer¬ 
cury Plumbi oxidum is changed to “ TAthargyrum, LithargePotassii 
sulphuretum is changed to u Potasses sulphurata , Sulphurated potash Po- 
tassce bitartras is changed to u Potasses tartras acida, Acid tartrate of potash 
Quince disulphas is now “ Quinics sulphas .” 
The most important of these changes are those made in the chlorides of mer¬ 
cury. The name by which medical men have been accustomed to prescribe, and 
chemists to dispense calomel, no longer applies to the mild mercurial which has 
been used in five-grain doses to stimulate the liver, but is a name now given to 
the poisonous corrosive sublimate which destroys life in such or even smaller 
doses. 
Chemical Notation .—We have now for the first time introduced into the ‘ Phar¬ 
macopoeia 1 the method adopted by scientific chemists of representing the compo¬ 
sition of chemical compounds by the use of symbolical formulae. Thus glacial 
acetic acid is represented byH0,C 4 H 3 0 3 , nitric acid by 3 HO, 2 NO s , etc. This 
method of representing chemical substances is often of great use. It serves to 
define bodies more precisely than can usually be done by any short and simple 
verbal description. Thus the above formula for acetic acid represents it as a 
perfectly definite compound of one atom, or fifty-one parts by weight, of anhy¬ 
drous acetic acid, and one atom, or nine parts by weight, of water. The body 
represented by the formula must consist of those ingredients in precisely those 
proportions and no others, whereas the name glacial acetic acid admits of slight 
variations in the proportion of water, and is applied to acetic acid which is 
strong enough to crystallize in cold weather. The objection to the use of the 
formula in such a case is that it has too precise a signification. The substances 
used in medicine are not generally required to be in a state of chemical 
purity, or in such a perfectly definite state as symbolical formulae would repre¬ 
sent. Some chemical bodies, it is true, assume such a state by crystallization or 
other means in process of manufacture, and when they do so, they are of course 
by preference used in such a state ; but it is often difficult to get bodies, espe¬ 
cially those that do not crystallize, in the state that would be represented by a 
chemical formula, and if required, they could only be produced at a greatly 
augmented price, while no advantage whatever would result in their use in 
medicine. It is only necessary to refer to a few of the instances in whichthese 
formulae are used in the British Pharmacopoeia to show the difficulties and incon¬ 
sistencies their employment leads to. Thus with regard to glacial acetic acid , the 
product obtained by the process given in the Pharmacopoeia will not accord with the 
formula. Indeed we may go further, and say that the process, strictly followed, will 
not yield glacial acid at all. If the use of glacial acid answering to suitable tests 
had been required, all difficulty would have been avoided, and the requirements 
of the case sufficiently fulfilled. The manufacturer, who best knows how to 
produce it, would furnish glacial acetic acid as near to the state of a monohy¬ 
drate, and as free from impurities as it can practically be obtained by any pro¬ 
cess that would not unduly augment its cost. Again in the case of nitric acid, 
the formula given represents an acid consisting of two atoms of anhydrous 
nitric acid, and three atoms of water, which is a colourless liquid, but the pro¬ 
duct obtained by the process given, and also the verbal description of the pro¬ 
duct which is appended to the formula, differ materially from the bt>dy repre¬ 
sented by the formula. We may also refer to the article on nitrite of soda, in the 
