November 23, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
401 
SPECIFIC GRAVITIES OF THE LIQUIDS 
OF THE BRITISH PHARMACOPEIA, 1887- 
BY CHARLES UMNEY. 
The insertion of the specific gravities of most 
of the liquids in the British Pharmacopoeia of 
18G7 was one of those prominent features which 
made it surpass its predecessor of 1864, and also the 
previous editions of the London, Edinburgh and 
Dublin Pharmacopoeias. 
The compilers undoubtedly regarded a determi¬ 
nation of the density of the officinal fluids, when 
compared with their behaviour with various re¬ 
agents, as one of the most rapid methods by which 
the value of such liquids could be estimated. 
Had the “ characters and tests ” of the Pharma¬ 
copoeia been enumerated without the addition of the 
specific gravities of the liquids, then they must 
have been considered as incomplete; on the other 
hand, if the specific gravities only had been given 
without the tests which have been wisely appended 
by the authors, then such data might have induced 
some to view a density determination as an in¬ 
fallible method of determining real value. 
To the pharmacist, the record of these specific 
gravities is of vast importance, as he is thereby 
enabled to make a comparison of the density of those 
liquids he receives in a manufactured form with 
those published in the Pharmacopoeia, and thus 
judge approximately of their strength and purity. 
Again, to the pharmacist, whose chief aim is to 
vouch for the value of every preparation he dispenses, 
no better means can be found for checking the ac¬ 
curacy of his work than a determination of specific 
gravity, and comparison of the results with the data 
of the Pharmacopoeia. 
In order to test the accuracy of the specific gravi¬ 
ties given in the Pharmacopoeia, I have from time to 
time since its publication made notes of numerous 
determinations, and more especiall} 7 in those cases 
in which I have found deviations from the offi¬ 
cinal density; the discrepancies noticed are but few, 
taking into consideration the numerous figures there 
given. 
. Thinking the publication of those specific gra¬ 
vities, which in my hands have seemed to differ 
from those of the Pharmacopoeia, would not only be 
interesting to the readers of the Journal, but also 
give other workers an opportunity of testing them 
accuracy, I have arranged side by side in the fol¬ 
lowing table the specific gravities as noted by me 
and those of the British Pharmacopoeia. 
[ B. P. 
Sp. Gr. 
Sp. Gr. 
1 Pound. 
| 
Acid. Sulphurosum (9 - 2 pr. cut.) 
1-040 
1-048 
Ext. Cinclionae Liquidum . . 
1-100 
1-122 
Liq. Bismuth! . . . . . 
1-122 
1134 
Liq. Calcis Chlorates . . . 
1-035 
1-050 
Liq. Ferri Perclilorid. Fort. 
1-338 
1-445 
Liq. Hyd. Nitratis Acidus . 
2-246 
2-130 
Liq. Plumbi Subacet. . . 
1-260 
1-270 
Liq. Sodae Cliloratae. 
1-103 
1-090 
Syr. Ferri Iodidi. 
1-385 
1-400 
Syr. Mori. 
1-330 
1-298 
Syr. Papaveris. 
1-320 
1-330 
Syr. Sennae. 
1-310 
1-320 
Tinct. Ferri Perchloridi . . . 
_ 
m ri ~ -:—— . 
•992 
1-007 
Third Series, No. 126. 
It cannot be too much impressed upon e/ery 
pharmacist that, in order to ensure the uni¬ 
formity so much to be desired in medicine, it is 
absolutely necessary that he should make frequent 
specific gravity determinations of those liquids which 
pass through his hands. 
To the manufacturer a knowledge of specific gra¬ 
vities is invaluable; having once verified the divi¬ 
sions on the scale of his hydrometer, he uses it 
without reserve; for by its indications he is enabled 
to judge of the care and diligence bestowed upon 
the fabrication of a solution, the component parts 
of which have previously come under his eye, even 
although he had no opportunity of watching the 
process. 
Add. Sulphurosum. —It has been shown (Pharma¬ 
ceutical Journal, vol. X. p. 516, and Proceedings 
of the Pharmaceutical Conference, 1869, p. 77) that 
a solution containing 9'2 per cent, of sulphurous 
anhydride will have a specific gravity of l - 048 and 
not P040, and that a solution of 5 per cent., the 
strength now generally adopted, is of specific gra¬ 
vity P027. 
Extract. Cinchona Liquid. —It is directed to eva¬ 
porate the aqueous extractive from one pound of 
Calisaya bark to three fluid ounces, or until the 
specific gravity be P200, and to this add one ounce 
of alcohol (•838). The resulting liquor is said to be 
1T00 (about). 
I have found that a mixture of fluid extract of 
cinchona and spirit of wine of the density described 
will be of specific gravity 1T22. I would modify, 
therefore, these directions, not only because of this 
discrepancy, but because they are wholly based upon 
an error, for it is assumed that three fluid ounces of 
liquor can be obtained from one pound of bark, a 
yield much beyond the average, and which would be 
defined with more accuracy as two fluid ounces. If 
the present proportions of volume of cinchona ex¬ 
tractive and spirit of wine are to be adhered to, 
then the Pharmacopoeia should direct that one- 
third of its volume of spirit of wine should be added 
to the fluid extract of cinchona, when the specific 
gravity would be 1T22. If, however, a 1T00 density 
be as concentrated as it is thought necessary to pre¬ 
pare the fluid extract of cinchona, then the directions 
should be amended thus: Evaporate the liquors to 
two fluid ounces , or until the specific gravity be 1T75 ; 
to this add one-tliird of its volume of rectified spirit, 
when the resulting liquor will have a specific gravity 
of about 1T00 (1T02). 
Liq. Bisinuthi. —Although perhaps the officinal 
method is seldom resorted to for the production of 
the liquor, still it would be well to amend the spe¬ 
cific gravity as it now stands in the Pharmacopoeia, 
to 1T34. 
Liq. Calcis Chloratce. —In this preparation we 
have an example of specific gravity being no indica¬ 
tion of strength, as the chlorinated lime from which 
this solution is prepared, is a mixture of variable 
proportions of hypochlorite, chloride and hydrate 
of calcium, the specific gravity being chiefly in¬ 
fluenced by the chloride of calcium present. I 
look upon the specific gravity P035, identical as 
it is with that of the Dublin Pharmacopoeia, 
as an error; for in my hands using 30 per cent, 
chlorinated lime the specific gravity has not 
been less than 1-050, and in taking good com¬ 
mercial chloride of lime I have found the specific 
gravity to be P057. Good commercial chlorinated 
