« AnteriorContinuar »
addition of albumen and acidulated water to an acidulated solution of half a grain of purified pepsin, mentioned above, furnished with chloride of sodium, a precipitate, which also had considerable digestive power.
Relation of Chloride of Sodium to the Digestive Power of Pepsin. By its preparation the commercial saccharated 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 determine 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.
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.
A solution of half a grain of purified pepsin in half a fluid-ounce of water, with 3 drops of hydrochloric acid, was mixed with 1 fluid. ounce of sherry wine, after twenty-four hours filtered, and then, with the addition of 150 grs. of coagulated albumen, exposed to a temperature of 105° F. After six hours-during which time the half-grain of purified pepsin in acidulated watery solution would have dissolved 250 grs. of coagulated albumen-of the 150 grs.
at least two-thirds yet remained. I added now 6 drops more of hydrochloric acid to bring the liquid to my standard acidity, but even at the end of twenty-four hours a large quantity of the albumen was undissolved.
New Method of Demonstrating and Measuring the Action of Pepsin. A. Gruenhagen. (Pflüger's Archiv., V., 203. Journ. Chem. Soc., 2nd series, X., 313.) In order to make the action of pepsin visible to a large class, the author recommends that a piece of
thoroughly moist blood-fibrin be placed in 0-2 per cent. of hydrochloric acid, till it swells up to a stiff jelly, and then laid on a funnel either with or without a filter. After the superfluous acid has drained off, a few drops of the digestive fluid, such as glycerin extract of pepsin are to be added to the jelly with a pipette. In about two minutes the fibrin becomes liquefied by conversion into peptone, and begins to drop from the funnel. The rapidity with which the drops fall indicates the intensity of the digestive action. To show the comparative digestive powers of concentrated and dilute solutions of pepsin, equal quantities of fibrin-jelly are to be laid on funnels of equal size, and equal quantities of the different digestive fluids added to each. The more dilute the solutions, the more slowly do the drops fall. To show the influence of temperature on digestion, pieces of fibrin are to be laid in funnels in the same way, one being kept at the temperature of the room, and the others warmed to the desired degree by a sand or water-bath, with a perforated bottom, and then the digestive fluid added. The rapidity with which the drops fall increases with the temperature up to a certain maximum, above which it sinks rapidly, and cannot be brought up to its former rate by rapid cooling.
Pharmacopæial Weights and Measures. (Pharm. Journ., 3rd series, ii., 461, 801.) Some attention has recently been directed to the subject of the weights and measures employed in pharmacy by a paper which was read at the Pharmaceutical Meeting in December, 1871, by Professor Redwood. The author discusses the question in relation to the preparation of a new edition of the National Pharmacopoeia. He expresses himself in favour of the ultimate adoption of the metrical system, but considers that the immediate introduction of this system into the Pharmacopoeia, to the exclusion of the old weights and measures, would be distasteful and embarrassing to a large proportion of those for whom the Pharmacopæia is intended. He considers that it would be more politic to afford the means of bringing about the change gradually, and recommends such an arrangement of the formulæ in the Pharmacopæia, as would leave it at the option of each individual to employ either the metrical system, or the old weights and measures.
There are two ways in which a gradual change might be in. troduced. One is to attach to each of the formulæ of the Pharmacopæia, as now constructed, a separate column of figures, representing the equivalent weights and measures, according to the metrical system, leaving it to the operator to adopt whichever system he may prefer; and the other is to substitute proportional or relational numbers for specified weights and measures, such numbers being equally applicable to either system.
The latter is the method preferred by the author. He proposes to use the term part to represent weight, and the term measure to represent volume.
The following examples will serve to illustrate the application of the proposed method to some of the processes of the Pharmacopoeia.
Antimonial Powder. ☆ Oxide of antimony
1 part. Phosphate of lime
2 parts. Mix them thoroughly.