December 3, 1870.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
443 
Chapters for SMrats. 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDEX, B.SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
Antimonii Oxidum. —Solution of chloride of an¬ 
timony is poured into water, and the white precipi¬ 
tate of oxichloride of antimony allowed to settle and 
partially washed by decantation. It is then digested 
with solution of carbonate of sodium till completely 
decomposed, and finally the deposited oxide is washed 
to free it from chloride of sodium. The reaction 
consists in the formation of an insoluble compound 
of oxide and chloride of antimony:— 
a;SbCl 3 + 3H 2 0 = Sb 2 0 3 , (x—2) Sb Cl 3 + 6HC1. 
The proportion of oxide in the precipitate increases 
with the proportion of water used for washing. The 
carbonate of sodium removes the last traces of chlo¬ 
ride— 
2SbCl 3 + 3Na 2 C0 3 = Sb 2 0 3 + GNaCl + 3C0 2 . 
Prepared in this way the oxide generally has a buff 
tint, from the presence of a minute quantity of oxide 
of iron. It can be procured perfectly white by redis¬ 
solving the washed oxichloride in hydrochloric acid 
and reprecipitating with water: the second washings 
should be performed with water to which a few drops 
of acid have been added. If heated too strongly or 
exposed to the air too much during drying, it is apt 
to become partially converted into the double oxide 
Sb 2 0 4 , formerly called antimonious acid. When in 
this condition it will not dissolve completely in acid 
tartrate of potash, as stated in the Pharmacopoeia. 
Antimonic anhydride is left— 
2 Sb 2 0 4 + 2KHC 4 H 4 0 6 
= 2 SbO K C 4 H 4 0 6 +Sb 2 O s + H 2 0. 
Antimonium Sulphur atom. —Black sulphide of 
antimony is powdered and boiled for two hours with 
solution of soda. The strained solution is then 
mixed with a slight excess of dilute sulphuric acid 
and the precipitate collected, washed and dried on a 
water bath. The sodic hydrate may be represented 
as acting two parts. One half undergoes decompo¬ 
sition with the sulphide of antimony, yielding sul¬ 
phide of sodium and oxide of antimony; the other 
half dissolves up the oxide of antimony, as it is 
formed:— 
Sb 2 S 3 + GNaHO = Sb 2 0 3 + 3Na 2 S + 3H 2 0. 
The sulphide of sodium that is produced takes up at 
the same time sulphide of antimony. Thus two 
soluble compounds result, the second being the coun¬ 
terpart of the first, but containing sulphur in place 
of oxygen, atom for atom:— 
3Na 2 0,Sb 2 0 3 = 2Na 3 Sb0 3 . 
3 Na 2 S, Sb 2 S 3 = Na s Sb S 3 . 
On the addition of sulphuric acid to the solution of 
these two, sulphide of antimony is alone deposited, 
for the sulphuretted hydrogen produced by the de¬ 
composition of the second compound suffices to con¬ 
vert the oxide of the first into sulphide:— 
Na 3 SbO, + Na s Sb S 3 + 3H 2 S0 4 
= Sb 2 S s -f 3H 2 0 + 3Na 2 S0 4 . 
This must, however, be accepted as an explanation 
only of the principal features of the decomposition ; 
other minor and more complex reactions go on simul¬ 
taneously. They arise chiefly from the action of the 
oxygen of the air during the boiling. 
If the alkaline solution be allowed to cool before 
the acid is added, a brown precipitate, a compound of 
oxide and sulphide of antimony, is deposited. This 
is what was formerly known and employed as mine¬ 
ral kermes. 
[§ Sixty grains of this preparation dissolved in 
hydrochloric acid and dropped into water give a 
white precipitate, which, when washed and dried, 
weighs about 53 grams.] This cannot be regarded 
as by any means a satisfactory test. If, for ex¬ 
ample, rather too much hydrochloric acid were em¬ 
ployed for dissolving it, a considerable proportion of 
the compound would be lost in the form of chloride, 
which would be retained in the mother liquor. A 
better plan would be somewhat as follows:—50 
grains moistened with nitric acid, then dried and 
heated to redness, would give a white residue weigh¬ 
ing about 45 grains. And the weight of this is not 
sensibly altered by washing with boiling water. 
Antimonum Tartaratum. —Oxide of antimony is 
mixed with cream of tartar and water into a paste, 
allowed to stand twenty-four hours, and then water 
added and the whole boiled up, filtered and set by to 
crystallize. A little antimonic anhydride, Sb 2 O s , is 
generally left insoluble in the form of a white 
powder. 
The formula of this compound, as given in the 
Pharmacopoeia, seems to be anomalous. It is better 
to represent it as a tartrate containing an atom of 
potassium and an atom of a compound radicle, to 
which it is not necessary to give a name, but which 
replaces the atom of basylous hydrogen belonging to 
the cream of tartar from which the salt is made. 
Antimony is usually trivalent, Sb'", the union of one 
atom with an atom of oxygen which is bivalent 0", 
gives, therefore, a compound which is univalent 
(Sb"'0"y. The formula of tartar emetic, written on 
this principle, is then (Sb0)'KC 4 H 4 0 6 . Crystals 
of the salt are easily recognized by their triangular 
facets, which are marked by parallel lines. A solu¬ 
tion of the salt in a mixture of hydrochloric and tar¬ 
taric acids gives with sulphuretted hydrogen an 
orange precipitate of sulphide of antimony. This 
compound, after being dried in a water bath, contains 
only a very small quantity of water (about 1^ per 
cent.); if heated more strongly it suddenly loses its 
amorphous state, becoming black and crystalline. 
It is then identical in composition with the native 
sulphide. 
Argenti Nitras. —Pure silver is dissolved in di¬ 
luted nitric acid, and the solution evaporated till it 
yields crystals:— 
3Ag 2 + 8 H N 0 3 = 6 AgN 0 3 + N 2 0 2 
+ 4H 2 0. 
Traces of gold, or of sulphide of silver, which may 
be present, will remain insoluble as a nearly black 
powder. Solutions of nitrate of silver are best de¬ 
canted from any sediment, not filtered, since contact 
with the organic matter of the filter renders the 
nitrate of silver liable to decomposition on exposure 
to light. Nitrate of silver is often made by dissolv¬ 
ing silver coins, or other form of common silver. 
Brazilian and Portuguese coins are used for this 
purpose. When this plan is adopted, the solution is 
evaporated to dryness and the residue heated strongly 
for some time. The nitrate of copper present is in 
