April 20, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
843 
and is agreeable when fresh. It is due, in part, to 
a crystallizable body called valerol, C 6 H 10 O, by the 
oxidation of which the valerianic acid derived from 
the plant is formed. 
2 C 6 H 10 O + 3 0 2 
Valerol. 
= a c 5 h 10 o 2 + a co 2 
Valerianic Carbonic 
Acid. Anhydride. 
(To be continued.) 
PEPSIjN. 
A NEW PRACTICAL METHOD TO PREPARE IT ; ITS 
PROPERTIES AND DIGESTIVE STRENGTH. 
BY E. SCHEFFER. 
(Concluded from page 785.) 
Relation of Chloride of Sodium to the Digestive 
power of Pepsin. —By its preparation the commercial 
saccliarated pepsin contains always a small quantity 
of chloride of sodium; in my experiment, to obtain 
a pure pepsin free of sodium chloride, I succeeded 
by using alcohol, but the resulting product had less 
digestive power than purified pepsin, which still 
contained salt. It was therefore interesting to deter¬ 
mine if chloride of sodium would aid the action of 
pepsin on albumen and accelerate its solution. 
A very small quantity of salt, a quantity that 
does not exceed much that of the purified pepsin, 
does not interfere with, on the contrary assists, the 
pepsin in its action; but a larger quantity, although 
very small in itself, retards the solvent power. 
While half a grain of pure pepsin in 2 oz. of 
acidulated water dissolved 200 grs. of coagulated 
albumen perfectly, a great deal of albumen was left 
undissolved in the same time when 5 grs. of salt 
were added to it, while by 10 grs. of salt a portion 
of the albumen was not dissolved after three days. 
Stability of Pepsin. —As watery solutions of pep¬ 
sin decompose very soon, particularly in warm 
weather, it was of interest to determine the stability 
of acidulated solutions ; accordingly solutions con¬ 
taining 1 gr. of purified pepsin to the fluid ounce of 
water, and respectively 2, 4, 6, 8 and 10 drops of 
hydrochloric acid were set aside, a portion of each 
in well-corked vials and another portion in vials 
only tied up with paper. The solutions containing 
2 drops of acid became mouldy after the first and 
second week, while in the vials with 4 drops of 
acid I noticed mould after five weeks. The other 
solutions kept entirely clear, and when examined 
after six months they did not have any bad odour, 
but had lost their digestive power almost entirely; 
albumen, put into several of the solutions, was 
hardly acted upon, and chloride of sodium did not 
produce the characteristic precipitate. 
To 20 grs. of purified pepsin, swelled in 2 oz. of 
water, were added 10 drops of hydrochloric acid, 
which dissolved the pepsin fully and formed a liquid 
of a slight yellowish colour and the consistence of 
the officinal mucilage of gum arabic. Put aside in 
a beaker-glass, tied up with blotting-paper, it evapo¬ 
rated slowly, and was, after six weeks, dried out to 
a transparent gum which felt sticky to the touch. 
Examined after several months, it dissolved readily 
in water, forming a clear solution of sour reaction 
and taste, which had no bad odour, but acidulated 
and diluted to the strength usually employed in my 
experiments, did not act on coagulated albumen, and 
chloride of sodium gave no precipitate. The pepsin 
was therefore totally destroyed or at least made in¬ 
active. 
Anxious to learn whether liquid pepsin, which 
had been put aside eight months before for experi¬ 
ments’ sake, had retained its digestive properties, I 
examined this and found that, although slower in 
its action it still dissolved albumen, and was also- 
precipitated by chloride of sodium. 
It seems, therefore, that the glycerine in the pre¬ 
paration of liquid pepsin prevented the pepsin from 
decomposing. 
In the spring I had set aside moist precipitate? 
(by chloride of sodium) of pepsin of the consistence 
ready for the press; when examined after six 
months it had a sweet odour, was pressed, dried,, 
and its digestive power ascertained, whereby it 
proved to have the same digestive strength as when 
quite freshly prepared. 
Several times the (chloride of sodium) precipitate, 
while draining on the cloth, was entirely frozen 
through, but proved, after thawing, not inferior in 
quality. 
The purified as well as the saccliarated pepsin, 
examined twelve months after preparation, proved 
to be entirely as good as when recently prepared; 
they had lost nothing of their strength, and dissolved 
albumen in the same time and in the same quantities 
as when quite fresh. The only difference is, that 
with age the dry pepsin dissolves somewhat slower 
in acidulated water. 
Action of Pepsin on Milk. —As the opinion is still 
prevalent, even amongst physicians, that only calf 
rennet has the property of separating the casein 
from the milk, or in other words, to coagulate milk, 
it was interesting to me to try the action of pepsin 
on milk. 
Five grains of saccliarated pepsin, swelled in a 
little water and then stirred into 1 pint of milk, 
coagulated the milk in thirty minutes. 
Of a solution of 2 grs. of purified pepsin, two drops, 
of hydrochloric acid and one fluid ounce of water, it 
took 5 drops to coagulate 4 oz. of milk in about 
twenty to thirty minutes; while 10 drops of dilute- 
muriatic acid (20 drops to 1 oz. of water) did not 
curdle 4 oz. of milk in four hours. 
Averaging 400 drops in a fluid ounce of the pepsin 
solution, it took one-fortietli ( 7 V) part of 1 gr. to- 
coagulate 4 oz. of milk, or 1 gr. to 5 quarts ; accord¬ 
ing to this test, 1 part of pepsin will coagulate about 
80,000 (eighty thousand) parts of milk. 
The success of these experiments depends a great 
deal on the temperature ; the best way is to add 
the pepsin to the milk when cold and then heat it 
slowly; when kept cold it takes much longer time- 
to coagulate the milk. Also when the milk is heated 
first, say to 100° F., before the pepsin is added, it 
takes three to four times as much pepsin to effect 
coagulation. 
Alcohol incompatible with Pepsin. —In my former 
articles written about pepsin, I have mentioned the 
incompatibility of pepsin and alcohol, and have 
spoken of the impropriety of dispensing pepsin in 
the form of wine or elixir. Having now a purer 
pepsin at my disposal than before, I repeated the 
experiments with entirely the same result. 
Seven vials of solution of pepsin, each containing 
