November 5, 1870.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
363 
i cases was perfect. The ether also forms an excellent 
mixture with bichloride of methylene; and if mix¬ 
tures of anaesthetic substances were satisfactory 
scientific applications, it might be brought into exten¬ 
sive use. Dr. Richardson accepts it, however, rather 
as an index of the way than of a resting-place. He 
looks for a simple ether which shall have the full 
and safe qualities of the mixture, together with per¬ 
fect Stability. There is, in truth, already another 
ether, called trimethylic, made by acting on methyl¬ 
ate of sodium, CH 3 NaO, with chloroform; the pro¬ 
duct being 3(NaCl), common salt, and C 4 Hi 0 O 3 , 
trimethylic ether. But tliis ether, which has a ya- 
pour density of 53, and a high boiling-point, is not 
quite, though it approaches, the substance required. 
■ ■ - - • - ■ ■ — — 
Cfrajters far j&taJrtnts. 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDES', B.SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
(Concluded from page 344.) 
Acidum Sulphurosum. —Strong sulphuric acid is 
heated with charcoal, and the resulting mixture of 
gases conducted by suitable tubes, first through a 
small quantity of water to free it from impurity, 
then into the water in which the sulphurous acid 
gas is to be dissolved. 
2 H 2 S 0 4 -f- C — 2 Ho 0 -f- 2 S 0 2 -f* C 0 2 . 
From this equation, it appears that the sulphu¬ 
rous acid gas evolved is mixed with half its volume 
of carbonic acid gas. The latter escapes. 
Sulphurous acid gas may be made in many other 
ways. 
By burning sulphur,—$ + 0 2 = S 0 2 . 
By the action of undiluted sulphuric acid on many 
metals, as on copper and mercury,— 
2H 2 S0 4 + Cu==CiiS0 4 -f 2H 2 0 + S0 2 . 
By boiling sulphur with sulphuric acid,— 
2H 2 S0 4 + S = 2H 2 0 + 2SQ 2 + $0 2 . 
Compare this with the action of carbon. 
Or by the action of acids on sulphites or hypo¬ 
sulphites. 
Sulphurous acid gas, sometimes called sulphur 
dioxide, is not an acid, but, like other anhydrides, 
generates an acid when united with water. 
S0 2 -f” H 2 0 = H 2 S0 3 . 
Sulphurous acid gas. Sulphurous acid. 
It is a pimgent gas, condensable to the liquid state 
by application of cold or pressure; soluble in water ;* 
the gas in a moist state, as well as the solution, 
possessing the power of bleaching organic colours. 
With sulphuretted hydrogen the solution gives a de¬ 
posit of sulphur with formation of w r ater and penta- 
thionic acid. 
S 0 2 + 2 H 2 S = 2 H 2 O -f- S 2 
and 
me ae^ie^eiFfor ~si§pimr?us Q acid and 
* It is proposed to employ a 5 per cent, solution, there 
being a little difficulty in preparing a liquid 01 the official 
strength as a commercial article. 
sulphites has been described under Acidum Aceticum. 
The solution, by exposure to the air, absorbs oxygen, 
and is soon converted into sulphuric acid. If fresh 
it gives no precipitate, or but a very slight one, with 
BaCL, hut a copious one if solution of chlorine be 
also added. In the latter case sulphuric acid is 
formed. 
H 2 S 0 3 -f- o H, + Cl 2 = H 2 S 0 4 + 2 H Cl. 
Sulphite of barium is soluble in acids, sulphate 
not so. Iodine does the same when the liquid is 
sufficiently diluted. 
H 2 S0 3 + 0H 2 + I 2 = H 2 S0 4 + 2HI. 
It niust not be overlooked that in more concen¬ 
trated solutions the reaction goes the other way, e.g., 
2KI + 2H 2 S0 4 = K 2 S0 4 + I 2 -f- 2H 2 O + S0 2 . 
The strength of sulphurous acid solutions is to be 
tested by the volumetric solution of iodine. The 
reaction has just been shown. As soon as the whole 
of the S 0 2 has been changed into H 2 S 0 4 , the next 
drop of iodine which is superadded remains in the 
liquid unchanged, and therefore forms with the 
starch previously added its characteristic blue com¬ 
pound. When tliis point is reached the dropping in 
of the iodine is stopped. 
3‘47 grams of the official sulphurous acid require 
for complete oxidation 100 c.c. of the vol. sol. of 
iodine. 1000 c.c. of the vol. sol. contain ^ of an 
atom of iodine, or 12*7 grams; 100 c.c. therefore 
contain of an atom, which, according to the 
equation already given, is sufficient for molecule 
of S0 2 , or *32 gram. This would be the quantity in 
3‘47 grams of the solution; it is equivalent to O'2: 
per cent. 
3'47 : 100 as ‘32 : 9 2. 
THE CITRATES OF THE U.S. PHARMACOPCEIA. 
BY C. LEWIS DIEHL. 
{Concluded from page 346.) 
Citrate of Iron and Quinia .—The formula of the United 
States Pharmacopoeia for this preparation is as fol¬ 
lows :— 
Solution of citrate of iron 10 fl. oz. 
Sulphate of quinia 1 troy ounce. 
Diluted sulphuric acid. 
Water of ammonia. 
Distilled water, each, a sufficient quantity. 
u Triturate the sulphate of quinia with six fluid ounces 
of distilled water, and having added sufficient diluted 
sulphuric acid to dissolve it, cautiously pour into the 
solution water of ammonia, with constant stirring, until 
in slight excess. Wash the precipitated quinia on a 
filter, and, having added to it the solution of citrate of 
iron, maintained at the temperature of 120° by means of 
a water-bath, stir constantly until it is dissolved. Lastly, 
evaporate the solution to the consistence of syrup, and 
spread it on plates of glass, so that, on drying, the salt 
may he obtained in scales. In thin transparent scales, 
varying in colour from reddish-brown to yellowish - 
brown, with a tint of green, according to the thickness 
of the scales. Its taste is ferruginous and moderately 
bitter. It is slowly soluble in cold water, more readily 
aia causes a whitish ciuiy 
precipitate of quinia; hut no sesquioxide of iron is 
thrown down.” , . . 
The solubility of this compound is so excessively spa¬ 
ring, even when heat is applied to favour it, that it 
is 
