THE NEW EDITION OF THE BRITISH PIIARMACOPCEIA. 
495 
going considerable modification, and that two systems of notation and two 
tables of atomic weights are now very generally in use. In consequence of 
these facts, it was represented to the Council on high chemical authority, 
that it would be advisable to avoid the use of any formulae in the preparation 
of the present edition. The Council, however, did not entirely adopt this 
view, but determined to represent chemical compounds of definite constitu¬ 
tion, both by the old and also by the new method of notation. In all cases, 
therefore, where chemical symbols are used, two formulae are given, one 
according to the old and the other according to the new system. These are 
distinguished from each other by the use of different types, the formulae 
according to the old system being printed in Roman type, and those according 
to the new system in the heavy Egyptian or Clarendon type. Thus Sulphate 
of Magnesia is described by the following formulae:— 
MgO.SO 3 . 7 HO or MgS 04 . 7 H 20 . 
This distinction of type is carefully observed throughout the work, and 
enables the reader to recognize at a glance the formulae of the one system 
from those of the other, while it gives an equally simple appearance to each. 
In the employment of these formulae for defining substances, a certain dis¬ 
crimination has been exercised. In the case of crystalline bodies of a pure 
and definite nature, the formulae follow the name, and frequently constitute 
the sole definition. But in the case of other substances, such as the liquid 
acids, the Caustic Alkalies, Lime, Sulphurated Antimony, and a few others, 
the formulae are inserted in the text of the description. Thus Sulphuric Acid 
is stated to be :— 
“ An acid produced by the combustion of sulphur and the oxidation of the 
resulting sulphurous acid by means of nitrous vapours. It contains 96*8 per 
cent, by weight of the sulphuric acid, H 0 ,S 03 or H 2 SO 4 , and corresponds 
to 79 per cent, of anhydrous sulphuric acid, SO 3 or SO 3 .’' 
The objection which was advanced against the formulae used in the previous 
edition,—namely, that in certain cases they expressed a quantitative compo¬ 
sition which the body did not really possess,—is thus obviated. 
In compliance with a generally expressed wish, the Doses of all the more 
important medicines are now for the first time introduced into the Pharma¬ 
copoeia. The quantities stated under this head are intended to represent 
average doses in ordinary cases for adults. We are expressly told, howeverp 
that “ they are not authoritatively enjoined by the Council, and that the 
practitioner must rely on his own judgment, and act on his own responsibility, 
in graduating the doses of any therapeutic agents he may administer to his 
patients.” 
N o alteration has been made in the weights and measures which in the 
edition of 1864 were directed to be used in the preparation of medicines. 
The volumetric solutions, however, which are used in certain cases for quan¬ 
titative estimation, are so arranged that they may be prepared and used 
either with the Eoglish grain weights and grain measures, or with the French 
metrical w'eights and measures. The figures involved in each case are the 
same ; they may be taken to represent grains and grain-measures, or grammes 
and cubic centimetres. This arrangement does not at all interfere with the 
other parts of the work, and it may pave the way for the further introduction 
of the French system at some future time, should the adoption of such a 
course be ultimately considered desirable. 
Such, then, are the general features of the book. Among the medicines 
it includes will be found, a large number of preparations which are familiar 
to our readers, but which w’ere excluded from tlie first edition. There are 
also some introductions which are novel, and among them two new classes of 
