March 23, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
761 
PEPSIN. 
A NEW PRACTICAL AND RELIABLE METHOD TO PREPARE 
IT; ITS PROPERTIES AND DIGESTIVE STRENGTH. 
BY E. SCHEFFER. 
When publishing my paper upon saccharated 
pepsin (American Journal of Pharmacy , January, 
1871)* my intention was to continue the experiments, 
then only hinted at, and to publish the results. I 
have since made a -large number of experiments, 
some of which I deem of sufficient importance to 
he made known, although my researches are not 
finished. 
The various methods for the preparation of pep¬ 
sin, as given by different authors, seem to be intended 
mainly for the purpose of experiments, and are so 
complicated that the difference in the properties 
characterizing the products is readily accounted for. 
The student of physiology may not shun the trouble 
attending these processes, but the manufacturer 
could not possibly resort to them, even if he were so 
inclined. 
The author of Leop. Gmelin’s ‘ Handbook of 
Chemistry,’ in the last volume of the work (issued 
in 1870) says, under the heading of pepsin:—‘‘The 
pepsin of commerce is either mucus of the stomach, 
scraped off and dried, or a mixture of pepsin, peptons 
and starch, containing a little lactic acid.” In wffiat 
way these commercial pepsins were prepared it is 
difficult to say, as most manufacturers have their 
own w r ay and keep it a secret; but in Europe, as 
well as in this country, most of these preparations 
died almost as soon as they were brought into exist¬ 
ence, as they did not come up to what they were re¬ 
presented to be. 
In the summer of 1870, while working* on and 
experimenting with liquid pepsin ( American Journal 
of Pharmacy , March, 1870), and at the same time 
trying to improve it, I discovered some tests which 
I considered useful in the preparation of dry pepsin. 
Before this I had wished to prepare pepsin in the 
dry state, but w T as not inclined to follow the tedious 
and in some waj r uncertain processes usually given. 
Following up the hint received by certain tests 
with a number of experiments, I succeeded at last 
in obtaining a very satisfactory product. 
The action of saturated solutions of some of the 
neutral salts of the alkalies on different protein sub¬ 
stances induced me to try their effect on pepsin. 
For this purpose I prepared an extraction of the 
mucous membrane of fresh hogs’ stomachs with 
water acidulated with muriatic acid, which after 
repeated ffltrations formed an opalescent yellowish 
liquid. Equal volumes of this liquid and of a satu¬ 
rated solution of sulphate of soda, when well mixed 
together, formed a precipitate, which was collected 
on a filter, pressed and dried ; a tery small quantity 
of it, dissolved in water with the aid of a few drops 
of hydrochloric acid, dissolved coagulated albumen. 
Other saturated saline solutions were now experi¬ 
mented with, viz. of sulphate of magnesia and chlo¬ 
ride of sodium, and also a solution of chloride of 
calcium of 1*27 sp. gr. 
By these solutions precipitates were likewise 
found to form, possessing properties identical with 
that obtained by sulphate of soda, but I finally de¬ 
cided to employ chloride of sodium as the precipitant, 
as by a comparative test, which of the four different 
salts w r ould produce the most precipitate, the pro- 
* Pharm. Jotjrn. 3rd Ser. Yol. I. p. 666. 
Third Series, No. 91. 
portion was: chloride of sodium 4, sulphate of mag¬ 
nesia 3^, sulphate of soda 2, chloride of calcium 1; 
so that chloride of sodium gave twice as much pre¬ 
cipitate as sulphate of soda, and four times as much 
as chloride of calcium. But besides the larger yield,, 
the sodium chloride has the preference for its anti¬ 
septic properties. A part of the precipitate, formed 
by sulphate of magnesia and allowed to remain in 
the liquid, had a putrid odour after the third day, 
while a moist precipitate, formed by chloride of 
sodium and set aside purposely for experiments, 
proved to be good after six months. 
Preparation of Pepsin. —On this basis I now 
began to prepare pepsin. Of the well-cleaned fresh 
hog stomach the mucous membrane is dissected off T 
chopped finely and macerated in water acidulated 
with muriatic acid for several days, during which 
time the mass is frequently well stirred. The re¬ 
sulting liquid, after being strained, is, if not clear, 
set aside for at least twenty-four hours in order to 
allow the mucus to settle. To the clarified liquid 
the same bulk of a saturated solution of sodium 
chloride is added, and the whole thoroughly mixed. 
After several hours the pepsin, which by the addition 
of chloride of sodium has separated from its solution, 
is found floating on the surface, from whence it is 
removed with a spoon and put upon cotton cloth to 
drain; finally it is submitted to strong pressure, to 
free it as much as possible from the salt solution. 
The pepsin, when taken from the press and allowed 
to become air dry, is a very tough substance, and 
presents, according to thickness, a different appear¬ 
ance, resembling in thin sheets parchment paper, 
and in thick layers sole leather; its colour varies 
from a dim straw yellow to a brownish yellow. Be¬ 
sides a little mucus, it contains small quantities of 
phosphate of lime and chloride of sodium, which, 
however, do not interfere with its digestive proper¬ 
ties, as they are found also in normal gastric juice. 
Saccharated Pepsin. —To work it into saccharated 
pepsin (American Journal oj Pharmacy , January, 
1871) the damp pepsin, as it is taken from the 
press, is triturated with a weighed quantity of sugar 
of milk to a fine powder, which, when it lias become 
air dry, is weighed again, the quantity of milk sugar 
subtracted and so the amount of pepsin found. The 
strength of this dry pepsin is now acertained by 
finding how much coagulated albumen it wall dissolve 
at a temperature of 100° F. in five or six hours, and 
after this sufficient milk sugar is added to result in 
a preparation of which ten grains will dissolve one 
hundred and twenty grains of coagulated albumen, 
and this preparation I have called saccharated pepsin. 
Purification of Pepsin. —Anxious to get the pepsin 
in its purest state, if possible chemically pure, I 
tried different methods, but have not succeeded as 
yet. In order to get a purer article I redissolve the 
pepsin, as obtained after expression, in acidulated 
water, filter the solution through paper and precipi¬ 
tate again with a solution of sodium chloride; the 
precipitate, after draining and pressing, is now free 
of phosphate of lime and mucus, but still contains, 
salt. In the freshly precipitated state the pepsin is. 
very readily soluble in water, and cannot tlieieloie 
be freed from adhering salt by washing. 
By allowing the pressed sheet of pepsin to get 
perfectly air dry—whereby it becomes, coated v ith 
a white film and small crystals of chloride of sod.um 
_and by immersing it then in pure water for a short 
time, the greater part of sodium chloride can be 
