December 9,1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
461 
THE SUBSTITUTION OF PROPORTIONAL 
OH RELATIONAL NUMBERS FOR SPE¬ 
CIFIED WEIGHTS AND MEASURES ;IN 
THE DESCRIPTION OF PROCESSES IN 
THE PHARMACOPOEIA* 
BY PROFESSOR REDWOOD. 
One of the questions tlint will necessarily arise in 
connection with the preparation of a new edition of 
our Pharmacopoeia, is that of the weights and mea¬ 
sures to be authorized or recommended for use in 
prescribing, dispensing and compounding medicines. 
The committee by whom the present edition of the 
British Pharmacopoeia was prepared have alluded, 
in the preface to that work, to two “grave defects ” 
in the system of weights principally employed in the 
description of pharmacopoeia processes, namely, “ the 
absence of any denomination of "weight between the 
grain and the avoirdupois ounce of 437"5 grains, 
and the fact that the ounce is not a simple multiple 
of the grain; ” and they have given, and to some 
extent used, a second or alternative system,—the 
metrical system, in which those, or similar, defects 
do not exist. This more perfect system having been 
thus approved, and having been adopted in most 
Continental countries and in this country for the 
purposes of science; moreover, the substitution of 
this system for British weights and measures being 
now sanctioned by law, and a knowledge of it being 
included among the qualifications which pharma¬ 
ceutical chemists are expected to possess,—it becomes 
important to consider whether we cannot adopt an 
arrangement in the Pharmacopoeia by which the 
employment of metrical weights and measures would 
be facilitated and promoted. Instructions for the 
use of these weights and measures in volumetric 
testing are given in the present edition of the Phar¬ 
macopoeia, but with this exception, the British sys¬ 
tem is used, and the processes are so constructed 
that the application of the other system, in many 
instances, involves a good deal of calculation. 
Yet, notwithstanding the fact, as thus shown, that 
there are defects in our system of weights, especially 
as applied to pharmacy, and some strong grounds 
for exchanging this system for another, I do not 
think the time has arrived at which it would be 
judicious or safe, in the administration of medicine, 
entirely to replace British weights and measures by 
those of the metrical system. Such a change, if it 
were now suddenly made, would be distasteful and 
embarrassing to a large proportion of those for 
whose use the Pharmacopoeia is intended ; and this, 
I believe, applies quite as much to medical as to 
pharmaceutical practitioners. There are, however, 
many physicians and pharmacists who are favour¬ 
able to, and prepared for, the change, and by whom 
an arrangement of the Pharmacopoeia that should 
afford easy means for effecting the transition from 
one system to the other, would be looked upon as a 
step in the right direction. 
Assuming, therefore, that this change is desirable, 
and indeed inevitable, but that it ought to be brought 
about gradually, we may profitably consider what 
are the means best suited for accomplishing such an 
object. 
There are two ways in which a gradual change 
might be introduced. One is to attach to each of 
* Read at the Evening Meeting of the Pharmaceutical 
Society of Great Britain, Dec. G, 1871. 
Third Series, No. 70. 
the formula) of the Pharmacopoeia, as now con¬ 
structed, a separate column of figures, representing 
the equivalent weights and measures according to 
the metrical system, leaving it to the operator to 
adopt whichever system he may prefer; and the 
other is to substitute proportional or relational 
numbers for specified weights and measures, such 
numbers being equally applicable to either system. 
There are some difficulties in the way of carrying 
out either of these methods. If we adopted the first, it 
would be found that in representing the equivalents 
of our system in terms of the other, it would be neces¬ 
sary to use such a multiplicity of figures as would 
prove cumbrous and inconvenient in their practical 
application. Moreover, to be consistent, the same 
method of giving the equivalents in terms of the alter¬ 
native system ought to be extended to every part of a 
process in which weights or measures are expressed, 
including the application of tests ; and this, if fully 
carried out, would greatly add to the length and in¬ 
tricacy of the descriptions of our processes, and 
tend to render them obscure. These objections ap¬ 
pear to present insuperable obstacles to the adoption 
of this as a general method of describing the pro¬ 
cesses, although there are a few instances in which it 
might be used with advantage. 
With reference to the second method, the principal 
difficulty in the way of its being applied arises from 
the defect, already alluded to, in our system of 
weights, namely, that the ounce is not a simple 
multiple of the grain; for as the quantities repre¬ 
sented in several of our processes, as they now 
stand, are expressed partly in grains and partly 
in ounces, it is sometimes impossible to give the 
proportions of the ingredients in whole numbers. 
There is also another difficulty, if liquids are to be 
measured volumetrically, and solid and liquid ingre¬ 
dients are used in the same process, arising from 
the necessity of referring to two different standards, 
one for the solids and the other for the liquids; for not 
only would this entail the use of different words to 
indicate the signification of the numbers when so 
applied, hut in many cases the numbers would not 
represent the proportional relation of the parts. 
These difficulties, however, might he met, and in a 
great measure obviated, by altering the proportions 
of the ingredients used in some of the processes, 
attaching to the numbers short affixes which should 
define their meaning, modifying the mode of arrang¬ 
ing or constructing some of the formula;, and omit¬ 
ting the application of the method in a few in¬ 
stances. 
I have been for some time endeavouring to apply 
this as a general method to he used in describing 
processes in the Pharmacopoeia; and my object oil 
the present occasion is to explain the way in which 
I think it might he made to accomplish the de¬ 
sired object; I wish also to elicit the opinions of 
practical pharmacists and others with reference 
to it. 
The first thing required is a definition of terms to 
be employed in connection with the numbers repre¬ 
senting relative quantities, for as these numbers would 
sometimes represent weight and sometimes volume, 
it would he necessary to distinguish one from the 
other. The term part might be used to represent 
weight , and the term measure to represent volume. 
These terms are commonly employed with such sig¬ 
nifications, and if it was clearly defined that parts, 
when used in connection with the proportional or 
