CHEMICAL NOTATION IN THE PHARMACOPCEIA. 
215 
again be chalked upon the screen at the Hoyal Institution ; yet this formula 
is the basis of the system of notation which is to be kept before all those who 
use the forthcoming Pharmacopoeia. On the other hand, the system of nota¬ 
tion framed in accordance with modern theories is not firmly established, and 
will doubtless undergo many modifications in the course of a few years. 
Our chemical reformers are not agreed as to the true molecular constitution 
of the lower chlorides of mercury and copper, the higher chlorides of iron, 
chromium, and manganese, and many other bodies; consequently, the for¬ 
mulae by which such bodies are represented must be regarded as provisional. 
Still, if symbolic formulae were indispensable in the Pharmacopoeiaj those 
adopted by any leading modern chemist would be far preferable to those 
based on ideas which are generally admitted to be erroneous. 
The double formulae of the forthcoming Pharmacopoeia will necessarily em¬ 
barrass pharmaceutical teachers and students, and will reflect a transitional 
state of chemical science which cannot endure long. 
I have taken some trouble to ascertain whether the chemical formulae of 
the present British Pharmacopoeia are essential to scientific precision, and 
have arrived at*the conclusion that a few trifling alterations in the pharma¬ 
ceutic and descriptive names, or in the definitions, would remove all ambiguity, 
and obviate the necessity of employing a single symbolic formula. The 
results of my investigation I now* bring before my fellow-members of the 
British Pharmaceutical Conference. 
Chlorides and Hydrochlorates .—The pharmaceutic names of tv\ elve com¬ 
pounds in this group are unambiguous. The names “ hydrochloric acid,” 
“ chloride of sodium,” “ chloride of calcium,” “ chloride of barium,” and 
“ chloride of zinc” denote the only known compounds of chlorine with hy¬ 
drogen and with the metals named. There is but one “ hydrochlorate of 
ammonia,” and but one “ hydrochlorate of morphia.” The two chlorides of 
mercury are clearly distinguished by their pharmaceutic names, “calomel” 
and “ corrosive sublimate.” The name “ terehloride of antimony” serves to 
distinguish the body to which it is applied from the only other known com¬ 
pound of chlorine and antimony, which is a pentachloride ; and the name 
“terehloride of gold,” in like manner, serves to distinguish the normal auric 
chloride contained in the test solution from a monochloride of gold with 
which we are acquainted. Again, the ferric chloride contained in one of the 
officinal solutions is distinguished from the ferrous chloride by the well- 
understood appellation of “ perchloride of iron ;” moreover, the ferrideyanide 
test proves that the solution does not contain the ferrous salt. There are, 
then, but two chlorides mentioned in the Pharmacopceia which are imper¬ 
fectly designated. These are the chlorides of tin and platinum contained in 
test solutions. The simple name “chloride of tin” does not inform us that 
the body to which it refers is the lower chloride of tin, or stannous chloride 
of modern chemists. Still, as the Pharmacopoeia gives explicit directions for 
preparing the test-solution, the present name, wffiich is recommended by its 
simplicity, might be safely retained. According to the modern atomic weight 
of platinum, the compound called “bichloride of platinum” is a tetrachloride. 
It would therefore, be better to apply to it the unobjectionable name of 
“ chloride of platinum.” No mistake could possibly arise from the use of 
this name, as the lower chloride, or platinous chloride# is insoluble in w*ater, 
and consequently could not be contained in the officinal test-solution. The 
symbolic formula of chloride of barium, given in the Appendix, expresses the 
proportion of w*ater in the crystallized salt; but, as chloride of barium inva¬ 
riably crystallizes with two combining proportions of water, the simple word 
“ crystallized,” if substituted for the formula, would imply the hydration of 
the salt. Again, in the case of hydrochlorate of morphia, the proportion of 
