November 16,1372.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
381 
THE PRESENCE OE SILVER IN COM¬ 
MERCIAL SUBNITRATE OF BISMUTH. 
BY CHARLES ERIN, F.C.S. 
In tlie June number, 1808, of tlie Pharmaceutical 
Journal will be found a short paper of mine on 
“ Commercial Bismuth,” in which I pointed out that, 
whilst the tests given in the Pharmacopoeia for bis- 
muthum purificatum excluded copper, and the pro¬ 
cess for purifying it eliminated arsenic and anti¬ 
mony, no notice was taken of the probable presence 
of silver, notwithstanding that it was known that 
commercial bismuth frequently contained silver. 
My attention was again called to the matter 
by receiving the other day from a well-known and 
highly respectable firm of manufacturing chemists 
a sample of subnitrate of bismuth, containing so 
much silver that when exposed to the light it became 
of a deep bluisli-black tint. I obtained a sample 
from another firm of at least equal standing as 
manufacturing chemists, and to my surprise I found 
that even this too contained a very appreciable 
amount of silver. Upon this I decided to investi¬ 
gate the matter further, and obtained samples from 
four of the first dispensing houses in London, and 
from respectable houses in the country, for exami¬ 
nation. 
Each sample was dissolved in nitric acid, diluted 
with an equal volume of water, the insoluble residue, 
if any, 'was collected on a filter, well washed first 
with diluted nitric acid, and afterwards with water, 
and then treated on the filter with ammonia. The 
presence of silver was considered sufficiently proved 
by the residue on the filter being blackened by ex¬ 
posure to light, by its being soluble in ammonia, 
and giving in its ammoniacal solution a light lemon- 
coloured precipitate, with iodide of potassium. The 
chloride was precipitated from the nitric acid solu¬ 
tion and weighed as chloride of silver in the usual 
way. In no case did diluted sulphuric acid give 
any precipitate, thus showing the absence of lead. 
Sample 1. The one first mentioned above. A 
very short exposure to light blackened it. Was 
not examined further, as the manufacturers ac¬ 
knowledged the contamination by silver. 
2. The second sample mentioned above con¬ 
tained much less silver than sample 1, but sufficient 
to give a distinct bluish tint "when exposed to light 
for two or three days. 
3. Not a subnitrate at all, but a basic subchloride, 
containing chlorine equal to 90 per cent, of BiOCl; 
not completely soluble in nitric acid, and contained 
silver. 
4. Contained silver and 3’9 per cent, of sub- 
cliloride. 
5. Contained traces of subchloride, but no silver. 
6. Traces both of subchloride and silver. 
7. Neither silver nor subchloride, 
8. Contained silver and 4'9 per cent, subchloride. 
9. Neither silver nor subchloride. 
10. Silver and traces of subchloride. 
11. Neither silver'nor subchloride. 
12. No silver, but 6’5 per cent, subcliloride. 
13. No silver ; traces of subcliloride. 
14. No silver, about one per cent, subchloride. 
15. Neither silver nor subcliloride. 
The samples showed great diversity in density 
and appearance. Sample No. 1 was a damp pow¬ 
der, having a strongly acid smell and reaction. I 
tun assured by manufacturers that subnitrate pre- 
Third Series, No. 125. 
pared strictly according to the Pharmacopoeia, after 
having been kept for about two months, developes 
so much acid as actually to eflervesce with car¬ 
bonates. After re washing, however, it becomes more 
basic and more s'table. 
In sample No. 3, obtained from a London dispens¬ 
ing house, the substitution by the manufacturer of a 
subcliloride for a subnitrate is of course unpardon- • 
able. I have understood that, owing to its being 
prepared at a less cost, there is a great deal of sub¬ 
chloride sold as subnitrate, but this is the first 
sample I have ever met with. 
I he subcliloride in the other samples, although 
in one instance it amounts to as much as 6‘5 per 
cent., I consider to be rather the result of careless 
manufacture than an adulteration. It would appear 
that after the bismuth is dissolved, the silver, which, 
as we have seen, must be frequently present, is pre¬ 
cipitated as chloride by hydrochloric acid, and re¬ 
moved by decantation. If this is done carefully, 
there could be no *obj ection to such a process, but 
that it is not generally done carefully is sufficiently 
proved by the presence of varying quantities of sub¬ 
cliloride and, in seven samples out of fifteen, of 
chloride of silver. Samples 7, 9, and 11, which are 
very pure, I find, on inquiry, were manufactured by 
Howards and Sons, Stratford. 
TINCTURE AND SYRUP OF ORANGE-PEEL 
AND TINCTURE OF QUININE. 
RY CHARLES SYMES, PH.D. 
The preparation of tincture of orange from fresh 
peel is a matter which has engaged my attention 
more or less during the last twelve years, and some 
few remarks on the observations I have made from 
time to time might not be out of place ; especially as 
very vague conclusions appear to have been arrived 
at on this subject at the last Pharmaceutical meet¬ 
ing, after a description of some (to my mindl un¬ 
satisfactory experiments by the President. 
On March 8tli, 1868, I brought the subject before 
the members of the Liverpool Chemists’ Association, 
exhibiting a sample of the preparation in question, 
and advocating its general adoption (vide Pharma¬ 
ceutical Journal, 2nd series, vol. IX., p. 522), but it 
received comparatively little attention, and it was 
overruled by Mr. Shaw (hi the chair) that the in¬ 
convenience of being unable to obtain fresh peel at 
all seasons of the year w r as sufficient to justify the 
continuance of the process according to the B.P. 
Tincture of orange is essentially a flavouring 
agent, possessing slight stomachic properties ; never¬ 
theless, it is the most important of its class, largely 
prescribed, and therefore meriting attention. In 
drying the peel, however carefully this is performed, 
a large percentage of the aroma is lost, which, if 
retained, makes a tincture of unquestionably superior 
flavour ; such being the case, any difficulty in pro¬ 
curing the fruit at some seasons is quite secondary. 
How easy would it not be to make many of the 
tedious pharmacopoeia preparations if we could rest 
satisfied with inferior results ? When this tincture 
has been kept twelve months the flavour is not 
quite so fine as when freshly prepared, but even then 
its superiority to tincture from the dry peel is evi¬ 
dent. 
Six ounces of peel, cut thinly from the fruit, weigh 
