JOTTINGS ON THE BRITISH PHAUMACOPCEIA. 
549 
quantity wliich the salts employed are theoretically capable of yielding, 
would only form 45'5 per cent, of the mixture, and I need not say that in 
practice this is never reached. For the 330 grain-measures ordered to be 
used, 210 should be substituted. 
Ferri et Quiniae Citras.—This salt is precipitated blue by both the yellow 
and the red prussiates of potash, although the solution of persulphate of iron 
is employed in its preparation. Can any light be thrown upon this anomaly ? 
for such I conceive it to be. 
Ferri Oxidum Magneticum.—The remark made above on ferri arsenias ap¬ 
plies to this also, which, if correctly represented by the formula Fe 3 0 4 , would 
contain 24*8 per cent, of FeO, whereas the result of the volumetric test shows 
the presence of only 8‘9 per cent. 
So also with Ferri Pkosphas, Fe 3 P 2 O s , since only 21 per cent, of metal in 
this salt, which contains 4G'9 per cent., appears to remain in the ferrous state. 
It may be worth while to note the strengths of a few officinal preparations, 
deduced from the atomic weights and other data given in the Pharmacopoeia. 
Liquor Ammonite Acetatis.—This contains 7 per cent, of NH 4 C 2 H 3 0 2 . 
Liquor Ammonise Citratis contains nearly 15 per cent, of the salt. 
Liquor Antimonii Chloridi.—One fluid drachm contains 29'5 grains of 
SbCl 3 , or 36‘7 per cent, by weight. 
Liquor Ferri Perchloridi Fortior.—One fluid drachm contains 31‘7 grains 
of Fe 2 CJ 6 . 
Liquor Ferri Pernitratis.—One fluid drachm contains 7’8 grains of 
Fe ? 6N0 3 . 
Liquor Ferri Persulphatis.—One fluid drachm contains 28 - 6 grains of 
Fe,3S0 4 . 
Liquor Plumbi Subacetatis.—One fluid drachm contains 18'5 grains of 
Pb 2 0 (C 2 H 3 0 2 ) 2 , or 26 - 8 per cent, by weight. 
Liquor Zmci Chloridi.—One fluid drachm contains 457 grains of ZnCl 2 . 
Tinctura Ferri Acetatis. One fluid drachm contains 4'16 grains of 
Fe 2 6C 2 H 3 0 2 . 
Mistura Ferri Composita.—This contains almost exactly one grain (1*05) of 
FeC 0 3 in each fluid ounce. The quantity of carbonate of potash used is just 
double that required to decompose the sulphate of iron. 
Pilula Ferri Iodidi.—This is described as containing one grain of the iodide 
in three of the mass, but one in three and a half would, I think, be nearer the 
truth ; the theoretical proportion being 1 in 3'68 grains. 
Potassii Bromidum.—In preparing this salt, the bromine appears to be used 
in large excess. Two pints of solution of potash contain 1080 grains of KHO, 
which would theoretically unite with 1543 grains of bromine,—four fluid 
ounces or 5190 grains of the latter being ordered. 
Potassii Iodidum.—The same remark applies, but less forcibly, to this salt; 
the quantity of iodine which combines with a gallon of solution of potash 
being 9797 grains and the quantity ordered 29 ounces, or 12,687 grains. 
Soda 3 Sulphas.—There is an error in the quantitative test given tor this 
salt: 50 grains are said to yield 72’2 grains of sulphate of barium ; whereas, 
a calculation based on the atomic weights shows that 100 grains are required 
to produce 72‘3 grains of the latter, 
Volumetric Solution of Oxalic Acid.—The B.P. states that 1000 grain- 
measures of this solution, containing 63 grains, are capable of neutralizing 
“ one equivalent in grains of an alkali or alkaline carbonate,” but if we pro¬ 
ceed to test the truth of the latter part of this statement, it will be seen that 
of the first alkaline carbonate on the list, Ammonite Carbonas bf 4 Hi 6 C 3 O s , 
59 grains, or only one quarter of an equivalent in grains, are neutralized by 
the given quantity of the solution; and a little consideration will show that 
