November 2, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
343 
is based upon tlie fact that it is but sparingly soluble 
in citric acid, or acid ammonium citrate. If, there¬ 
fore, citric acid is added to a moderately dilute solu¬ 
tion (about thirty of water to one of the oxide) of 
ammonio-bismuthous citrate, the ammonia is con¬ 
verted into acid salt, and the bismuthous citrate 
slowly separates in crystals. Hather more than two 
ounces of citrate are thus produced from one ounce 
of the oxide. The writer deems this process superior 
to all others at'present known, as by it the metallic 
citrate can be easily and cheaply made in large quan¬ 
tities, for the preparation of all compounds into which 
this citrate enters, and, moreover, as it could be more 
extensively used in medicine directly by supplanting 
some of the less desirable bismuth salts. This 
process is rendered practicable by dissolving metallic 
bismuth in nitric acid, diluting the solution to about 
thirty times the weight of the metal by adding water, 
then introducing only the necessary quantity of citric 
acid to form metallic citrate, and then adding am¬ 
monia until a small portion of the precipitate which 
each addition causes remains undissolved, then set 
the liquid aside for twenty-four hours, to allow the 
salt to crystallize. Another small crop of crystals 
can be obtained by cautiously mixing more ammonia 
with the mother-liquor ; or the ammonia can be first 
added to the concentrated solution, and then be 
diluted. 
The citrate is readily and completely soluble in 
ammonia, in nitric and in hydrochloric acid, but se¬ 
parates in granular crystals when the nitric solution 
is diluted with water. A precipitation results when 
the hydrochloric solution is diluted, but this precipi¬ 
tate is not the citrate, as it is insoluble in ammonia. 
In this connection the writer finds it convenient to 
state that the officinal process for basic bismuthous 
nitrate does not by any means yield a preparation of 
the supposed composition. Becker shows that the 
curdy precipitate produced by adding water to a solu¬ 
tion of the normal nitrate is the body which answers 
to that composition, and that if this be treated with 
water a much more basic salt is formed. If this be 
further treated with hot water, a dingy white residue 
remains, containing only one or two. per cent, of 
nitric acid. The writer finds the best method for 
producing the medicinal nitrate in the form of a loose 
crystalline powder is to dilute the solution to about 
thirty times the weight of the metal, and then adding 
ammonia so as to leave the liquid slightly acid. 
After subsiding, the precipitate is transferred to a 
filter and washed with a moderate amount of water. 
Mr. Scheffer considers it impossible to combine 
bismuth with pepsin in permanent solution. The 
writer finds that the syrup above prepared is perma¬ 
nent, but cannot vouch for the activity of the pepsin 
contained in it. That the pepsin originally intro¬ 
duced is still in solution is unquestionably certain, as 
no precipitation of any character whatever had taken 
place after the mixture of the two solutions was 
effected; and that these were of a decided acid re¬ 
action before and after the mixing is also a positive 
certainty; yet with all this, the writer has made the 
observation that the presence of bismuth utterly vi¬ 
tiates the method of assay by which the power of the 
simple pepsin solution is ascertained, and in tills 
respect Mr. King is most grievously mistaken. 
Mr. King attempts to show that in an alcoholic 
preparation, in the production of which a certain 
amount of a questionable quality of pepsin had been 
used, tbe pepsin could be determined by the amount 
of coagulated albumen it was capable of dissolving. 
But Mr. King did not exercise the necessary discre¬ 
tion to judge rightly between albumen actually dis¬ 
solved and difference of weight caused by shrinkage. 
To exemplify tills, the following experiments will 
suffice :—Firstly, let it be premised that dissolving 
albumen never shrinks, but, on the contrary, expands 
and becomes soft and pulpy as the solution pro¬ 
gresses, and that solution results much more rapidly 
towards the last than in the beginning, because at 
the outset the albumen is more compact, and pre¬ 
sents less surface. To facilitate the solution, and 
give the pepsin full scope, the writer introduces the 
albumen not in cubes, but in very thin slices or 
ribbons. 
The writer, in the experiment with syrup of pepsin 
with little water, found that no apparent action of the 
pepsin could be observed, but, on the contrary, the al¬ 
bumen had considerably gained in weight, whilst pre¬ 
serving its compactness. But now 6 fluid drachms of 
syrup of pepsin and bismuth were acidulated with 
hydrochloric acid in sufficient excess to prevent preci¬ 
pitation, diluted with water to a little over a fluid 
ounce and 45 grains of coagulated albumen added, and 
a proper temperature maintained. During a digestion 
of twelve hours no impression appeared on the albu¬ 
men. It was then removed, and found to have a 
hard and compact exterior. It had lost 15 grains of 
its original weight in opposition to the large presence 
of syrup. The writer does not hesitate to say that 
no albumen whatever was dissolved, but the loss was 
simply caused by the abstraction of water. 
1^ fluid ounces of syrup of pepsin and bismuth 
was diluted with water to 5 fluid ounces, and acidu¬ 
lated with enough hydrochloric acid to prevent pre¬ 
cipitation. 95 grains of albumen in cubes was 
digested with this for eight hours. A very con¬ 
siderable contraction occurred, but the firm exterior 
remained unyielding for a long time. The cubes 
were then crushed with a glass rod. The peculiar 
tenacity, differing from that of freshly coagulated 
albumen, was remarkable. The crushed albumen, 
after at least four hours’ digestion, was carefully 
collected on a strainer, and dried between folds of 
bibulous paper, weighed 45 grams, showing that the 
original weight had sustained a loss of 50 grains. 
Simultaneously with the preceding experiment, 11- 
fluid ounces of syrup of pepsin and bismuth was 
diluted with water to 4 fluid ounces, and acidulated 
with hydrochloric acid beyond the limit of precipita¬ 
tion, and 95 grains of coagulated albumen in cubes 
was digested in it for eight hours without rupturing 
the cubes. These had the identical appearance of 
those in the parallel experiment, and weighed 
exactly the same. 
The residue of the first of these two experiments 
was washed with water, then thoroughly triturated 
in a mortar, and digested with 0 fluid drachms of 
acidulated water for four hours; as no change of 
appearance took place, an unfiltered hydrochloric 
solution of pepsin, representing 0 grains of sac- 
charated pepsin, was added, and the digestion con¬ 
tinued four hours longer. The insoluble residue was 
then carefully collected on a strainer, the superabun¬ 
dant moisture absorbed with bibulous paper, then 
scraped up cautiously and weighed. 15 grains out 
of the 45 was still left. Tins, however, was a purely 
white flocculent sediment. When boiled with diluted 
nitric acid it turned intensely yellow from the forma¬ 
tion of xanthoproteic acid; and ammonium sulphide 
