I then tried plain filters off the same sheet against each other in like funnels; usually the results varied but a few per cent., though sometimes much more; the greatest difference noticed was 2 to 1; several times the results corresponded exactly on repeated runs of 500 cubic centimetres.

Experiments were made to determine the difference in efficiency between the single and the triple sides of filters. No. 1, had its triple side covered with paraffin, leaving the single side free. No. 2 had the triple side free, while the single was covered; with paraffin the result was 175: 100; glycerin was then tried with the result 200 100, showing the additional paper considerably retarded the flow.

I thought, since the adhesion of the water to the glass is the cause of slow filtration, I might increase the flow by coating the funnels on the inside with paraffin, to which water does not adhere. No. 1, being coated, No. 2, left clean, I got

84: 100

3d trial, 4th "

I. II. 100 100

137 100

2d 66 The filters in the third and fourth trials were the same, but the

funnels were changed about.

The outside or skeleton filters, above described, may be cut the same size as the inner filter; if much smaller the upper part of the inner filter clings to the glass; if larger a part of the precipitate is liable to adhere to the outer filter, and even with great care a part of the precipitate would creep up and be lost.

Boston, Feb. 1868.

ON THE PHYSICAL CHARACTERISTICS OF THE OFFICINAL POWDERS.

BY CLEMMONS PARRISH.

[An Inaugural Essay, presented to the Philadelphia College of Pharmacy.] The new feature of the Pharmacopoeia of the United States, by which powders are classified with reference to their degree of fineness, has not, I believe, been the subject of much experiment with a view to determine the actual physical condition of different drugs when brought to the officinal standard of pulverization.

The Pharmacopoeia does not indicate whether a powder of a specific grade is designed to be composed of particles of the designated degree of fineness or coarseness, or is intended to be a mixture of all the powders, resulting from the process, which will pass through the prescribed sieve. It could hardly have been designed that the powders, prepared for percolation, should consist of particles of uniform fineness, although, theoretically, this is the object in view. The experiments upon which the statement is based, that a uniform degree of fineness in powders is essential to the most perfect exhaustion by percolation, have, I believe, all been made with powders of uncertain physical composition.

The investigations detailed in this Thesis have been chiefly directed to ascertain the difference between the results of contusion and those of trituration, and are calculated to prove this obvious diversity, and to throw light upon the subject of pulverization generally. In order to make these experiments correspond to the ordinary conditions of the dispensing store, the apparatus employed were, first, a quart iron mortar and pestle of ordinary shape; second, a small mill of usual construction, such as are sold for domestic use and commonly used in pharmaceutical stores. The sieves were of the five grades prescribed by the Pharmacopoeia, viz.: No. 20, No. 40, No. 50, No. 60 and No. 80, having respectively these number of meshes to the linear inch. They were five inches in diameter, with well adjusted top and receptacle of tinned iron. The drugs were, first, gentian, suitably dried before weighing; second, the inner bark of wild cherry; third, decorticated ginger; fourth, ergot; fifth, Calisaya bark. The contusion was accomplished in the ordinary way, removing the drug from the mortar to the sieve at intervals, say three times, until the whole quantity experimented with passed the coarsest sieve, care being taken to observe uniformity throughout all the experiments; the sifted portions not being returned to the mortar after once passing through the sieve. In the use of the mill the drug was reduced so as to pass through the coarsest sieve by two or three grindings without previous sifting, the larger drugs being first sliced to adapt them to the mill, and the mill being set to the same point for each operation. The method pursued is believed to be that most practiced in the

processes of contusion and grinding as ordinarily accomplished. After obtaining the "coarse powder," U. S. P., passed through the No. 20 sieve, the proportion of the several other grades contained in it was ascertained by successive siftings; in each case the No. 40, No. 50, No. 60 and No. 80 sieves being successively used. The powder passing through No. 40 is the officinal moderately coarse, though containing Nos. 50, 60 and 80 powder; that passing through No. 50 is moderately fine, though containing No. 60 and 80; that passing through No. 60, though fine U. S. P., contains also the very fine, which is not separated until the No. 80 sieve is used.

The results are here tabulated, in the instances of gentian and wild cherry the average of several operations being given; in the others, carefully noted results of one trial:

Table showing the percentage of Powders of the several officinal grades in specimens of "Coarse" (No. 20) Powder, U. S. P.

It will be seen that the greatest difference in results between grinding aud contusion, in the above, is in the case of Peruvian bark, the short fibres of which, subjected to grinding, most readily pass into coarse powders, whilst contusion produces a

large proportion of a fine dust which will pass through the No. 80 sieve. If the whole had been subjected to contusion until it would pass the coarsest sieve, a still larger proportion of the finer grades would have been contained in the resulting powder. The ordinary method was, however, adopted in this as in the other experiments, the finer particles being three times separated as the contusion proceeded. Wild cherry gives nearly the same difference, more of the finest powder being produced by contusion at the expense of the coarsest, the intermediate grades differing but little in relative weight.

Ginger, by contusion, seems to increase in the proportion of No. 50 and No. 60 powder; its starchy character probably being unfavorable to its ready reduction to "very fine powder." The loss in ginger is greater than in any of the other experiments, chiefly from the fibre, a portion of which failed to pass the coarsest sieve, and may be called "gruffs."

Ergot, which has a corneous and oily character unfavorable to breaking up into fine dust, gives nearly uniform results by either method, the proportion of fine powder being very small, especially in the triturated specimen.

Gentian, of which the average of several experiments is given, furnishes decided evidence of the general fact that the pestle and mortar are more favorable to the production of the finer grades of powders than the mill. In the single experiment tried with Swift's mill the No. 40 and No. 50 powders were in larger proportion than when the small mill was used, but the No. 60 and No. 80 powders are nearly in the same proportion and decidedly less than the results of contusion.

The Swift's mill is not well adapted to use with so small a quantity of material, on account of the great extent of the rough grinding surfaces.

These experiments, though only conclusive upon the one point of the relative preponderance of the finer powders as the result of contusion, tend to show the great diversity of results by the different means of mechanical division, even when applied to the same drug, and especially when applied to drugs of different structure, and prove that the grades of powder indicated by the

officinal standard are of only approximate uniformity in physical composition.

The still more important inquiry into the chemical and therapeutical composition of the respective grades, as separated by sifting, which would be a difficult though important inquiry, does not enter into the scope of this essay.

CHLORODYNE.

BY EDWARD MCINALL, Jr.

(An Inaugural Essay, presented to the Philadelphia College of Pharmacy.) An empirical preparation called chlorodyne, of which so much has been said during the past few years, originated in England, about the year eighteen hundred and sixty. The one claiming to be original was that introduced by Dr. J. Collis Brown, and since its introduction there have been many imitations, both in Europe and the United States. Among.some of the English preparations may be mentioned Freeman's Chlorodyne and Towle's Chlorodyne, all purporting to be original articles, but I think that of Brown has the proper claim to originality.

Owing to the cost of importation and indeed its high price on the other side of the Atlantic, many of our Pharmaceutists have been induced to imitate it.

I have examined the many published formulas, but find most of them in a degree impracticable. The Chlorodyne of Brown is a thick viscid mixture, having a strong chloroformic odor combined with the pungency of capsicum, with a greenish hue.

Now the advantage of being syrupy is, I think, entirely unwarranted. The idea of using glycerine or treacle is to unite the morphia and chloroform more intimately together; but what may the need be, if it can be done without.

Another disadvantage in some of these imitations is the use of oil of peppermint. The liability of mistaking chlorodyne for essence of peppermint, as now directed by our Pharmacopoeia, at once suggests the abandonment of the use of peppermint as a flavoring ingredient in so powerful a combination. I was led to make, not an imitation of Brown's, but a preparation in which efficacy and practicability were combined. In the