February 18,1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
CG5 
drochloric acid; and a maroon-red precipitate (ferro- 
cyanide of copper (Cu 2 Fe C 6 N 6 ) with yellow prussiate 
of potash.] Much of the blue vitriol of commerce 
contains a considerable amount of sulphate of iron; 
to detect it the test given in the Pharmacopoeia may 
be employed. It is first mixed with chlorine water, 
to convert the ferrous into ferric salt, and then am¬ 
monia is added in excess. If iron is present in any 
notable quantity, it makes its appearance as a brown 
precipitate floating in the deep-blue liquid. Minute 
quantities may, however, easily be overlooked. 
.Emplastrum Plumbi.— Oxide of lead (litharge) in 
fine powder is boiled for some hours with olive oil 
and water, the latter being supplied as it evaporates. 
The Pharmacopoeia gives no directions as to what is 
to be done with the solution of glycerine, which is 
mixed up with the plaster at the end of the process; 
most of it is usually squeezed out and rejected. The 
reaction which takes place is an interesting one. 
Olive oil is a mixture of a fluid fat, olein, and a solid, 
usually called margarine. Since the olein forms the 
chief bulk of the oil, we will consider the action of 
the hydrated plumbic oxide upon that only. 
2(C 3 H 5 3C 13 H 33 0 2 ) + 3(Pb0,H 2 0) 
Oleiu or Hydrated 
Trioleate of Glyceryl. Oxide of Lead. 
= 2(C 3 H 5 3 HO) + 3(Pb2C 13 H R3 0 2 ) 
Glycerine Lead Plaster 
or Hydrate of Glyceryl. or Oleate of Lead. 
This decomposition it will be seen, notwithstand¬ 
ing the complex character of the radicles involved, is 
really a very simple one, being a double decomposi¬ 
tion analogous to that by which, for instance, ferric 
hydrate is produced from a ferric salt. 
2(GF01 3 ) + 
Oleate of Glyceryl. 
=2(G1'"3H0) + 
Hydrate of Glyceiyl. 
. Fe 2 3 S 0 4 + 
Ferric Sulphate. 
= Fe 2 OHO + 
Ferric Hydrate. 
3(Pb2HO) 
Hydrate of Lead. 
3(Pb01 2 ). 
Oleate of Lead. 
ONaHO 
Hydrate of Sodium. 
3Na 2 S0 4 . 
Sulphate of Sc d'um. 
The process of saponification is similar. A fat 
boiled with a solution of caustic alkali yields a soap 
and glycerine. 
Gl"/01 s 
Olein or 
OU*te of Glyceryl. 
=Gl ,w 3HO 
Glycerine or 
Hydrate of Glyeeryl. 
+ 
+ 
3 Nall O 
Hydrate of Sodium. 
3 Na 01. 
Hard Soap 
or Oleate of Sodium. 
Ferri Arsen ias. —See Acklam Arseniosum. 
Ferri Caebonas Saccharata. — [§ Carbonate of 
iron, FeC0 3 , mixed with peroxide of iron and 
sugar.] 
Hot solutions of carbonate of ammonia and sul¬ 
phate of iron are mixed together, and the resulting 
precipitate after the effervescence is over, is collected 
and washed with boiling water. The mother liquor 
having been, as far as possible, squeezed out, it is 
then mixed with sugar and dried over a water-batli. 
The white precipitate which is first formed is 
probably the ferrous carbonate— 
(N H 4 ) 2 C 0 3 + Fe S 0 4 = (N H 4 ) 2 S 0 4 + Fe C 0 3 ; 
but it very soon becomes green, carbonic acid gas 
escaping. Its constitution is then probably analo¬ 
gous to that of carbonate of zinc :— 
3 FeC0 3 + 2H 2 G 
becoming Fe C0 3 2 [Fe (H 0),] + 2 C 0 2 . 
Subsequently, upon exposure to the air, oxygen is 
absorbed, and a brown hydrated ferric oxide is pro¬ 
duced. To retard this change as much as possible, 
it is advisable to employ solutions more concen¬ 
trated than those ordered by the Pharmacopoeia. I 
have found it a good plan to throw into the hot solu¬ 
tion of the carbonate the powdered ferrous sulphate 
in the solid state, and to keep the mixture nearly 
boiling for about a quarter of an hour. In this way 
a very dense precipitate is produced which does 
not so rapidly undergo oxidation. 
The product should be grey, not brown, in colour, 
and should effervesce when introduced into an acid. 
[§ 2 grams dissolved in excess of hydrochloric 
acid and diluted with water, continue to give a blue 
precipitate with the red prussiate of potash, until at 
least 22* cubic centimetres of the volumetric solu¬ 
tion of bichromate of potash have been added.] 
The action of bichromate of potash on an acid so¬ 
lution of a ferrous salt is shown in the following 
equation:— 
6 Fe Cl 2 + 14HC1 + IC 2 Cr 2 0 7 
— 3Fe„Cl 6 “+ 2 K Cl + Cr 2 Cl 6 + 7H 2 0. 
Every molecule of red chromate, weighing 295 
grams, will convert into a ferric salt six molecules of 
any ferrous salt; and, at the end of the reaction, the 
solution will no longer give a blue precipitate with 
red prussiate of potash. Now, 20,000 c. c. of the 
volumetric solution contain one molecule of the red 
chromate. If, therefore, 22 c. c. of solution were 
used in an experiment, this quantity would indicate 
the presence of ’7650 gram of ferrous carbonate in 
the 2 grams of saccharated carbonate. For 
G Molecules 
of Fe C0 3 . 
20,000 : 22 : : 000 : ‘7056 
This amount represents 38'28 per cent., which is 
about the average in good samples. By calculation 
from the proportions of the ingredients, it should 
contain 45*5 per cent, of FeCO s . 
GINSENG. 
BY JOHN E. JACKSON. 
The history and uses of the Ginseng of the Cliinese 
are so well known, and are likewise so interesting, that 
some additional interest may be given to the subject 
to learn how the trade in tins article fluctuates in 
Cliina. The importations to Canton have of late 
very much declined, large quantities being now sent 
to Hongkong, where a process of clarification has 
been established. The roots are also imported and 
exported free of duty, while in Canton an import 
duty is first levied, and in addition to this a coast 
trade duty, if re-exported to other provinces. Of 
true Ginseng the produce of Panax Schinsciuj, Nees, 
three kinds are known in Chinese commerce—Man¬ 
churian, Corean, and Japanese. The first of these 
is the finest, but is scarce, being in fact an Imperial 
monopoly, so that the very best sorts are not seen in 
the markets. American Ginseng, P. quinquefolium , 
L., appears still to be taken into Cliina, but it is 
little appreciated by the Chinese. In America it is 
not employed as a medicine, and is considered to 
have no otlnr properties than a simple demulcent. 
* The Pharmacopoeia runn ier ccrrccie l. 
