dried juices from the leaves of plants, and, therefore, containing chlorophyl. Such inspissated juices are prepared by bruising fresh leaves or herbs in a stone mortar, pouring off the greenish liquid, and allowing it to stand over night. The liquid is then strained through calico, thereby separating the chlorophyl; the strained liquid is heated to 200° F., which coagulates the albumin present, and this is removed by straining. The clear liquid is then evaporated to a thin extract, to which is added the chlorophyl, and the whole mixture is evaporated until it is of pilular consistence. Were the plant-juices evaporated to extract directly on separating from the plant, the delicate chlorophyl would be quickly decomposed and a brown extract would result.

By first removing the chlorophyl and evaporating the mixture to a thin extract, the chlorophyl is preserved. When added just as the extract is reaching pilular consistence, it has the effect of giving to it an agreeable green color.

Such inspissated juices, as of aconite, belladonna, and hyoscyamus, are very popular in England, but are scarcely used in this country, and it should be borne in mind that these English "extracts" are much weaker than are the official American extracts.

Of these 28 extracts, 13 are powdered, while 15 are soft, the last class including those of pilular consistence; one thin as honey (extract of malt); and one almost brittle (extract of glycyrrhiza).

Two are alcoholic-that is, made with alcohol, U. S. P., as menstruum (3, if extract of cimicifuga, made by evaporating the fluidextract, is included); 5 are hydro-alcoholic (13, if those made by evaporating the fluidextract are included); 7 are aqueous, that is, made by evaporating the watery percolate, infusion, or decoction; 2 are acetic; that is, made by extracting drug wth a diluted acetic acid; and one is made by extracting drug with water containing ammonia.

Taking up the several methods of preparing extracts outlined in the table just given, a few words of general explanation of each process may be in place at this time, leaving, of course, minutiæ for consideration under Special Notes.

In the process of percolation with evaporation, when the menstruum is hydro-alcoholic, the drug is percolated with the official menstruum, the first portion of the percolate (usually representing in cubic centimeters 90 per cent. of the weight in grammes of the drug) is put aside as a reserve portion. The remainder of the percolate is evaporated at a low temperature to a very small bulk. With this the reserve portion is mixed, and the mass evaporated to pilular consistence.

The manufacture of extracts by this process is one portion of pharmaceutic manufacturing which cannot be done as well by the retail pharmacist as by the large manufacturer. In order to successfully evaporate the extract at a low temperature-say, 50° C.— it is necessary that a vacuum apparatus be employed, and the cost of such an apparatus precludes its use by the retail pharmacist.

In other cases where alcoholic menstruum is employed, none of the percolate is set aside as reserved portion, but the entire percolate is directly evaporated. This is the case where alcohol, U. S. P., is the menstruum, or where the constituents of the drug are not easily injured by heat. Likewise, if the menstruum is water or a diluted acetic acid, there is no reserve portion, but the entire percolate is evaporated.

The process of evaporation of the fluidextract, which was recognized in the pharmacopoeia of 1890 in only one case (extract of ergot), but which constitutes the official recipe in nine extracts of the present pharmacopoeia, is really a modification of the process of percolation with evaporation; since the fluidextracts, themselves prepared by percolation and possibly partial evaporation, are in the recipe evaporated. One point regarding this process worthy of note is that six of the extracts so prepared are directed to be of pilular consistence, while three are to be powdered extracts, and that these powdered extracts are prepared by incorporation of enough powdered glycyr rhiza to make the extract dry and pulverulent. In passing, it might be stated that the pharmacopoeia (Introduction, p. lii) permits use of exhausted marc of the drug instead of powdered glycyrrhiza.

The process of evaporation of infusion or decoction simply consists of extracting the drug with water-either by infusion or decoctionand evaporation of the watery solution either to pilular consistence or by finishing of the product as a powdered extract. As mentioned above, extracts are made pulverulent by addition of some inert pow

der. Glycyrrhiza is frequently the diluent, but in many cases, as in extract of opium, sugar of milk is employed. Usually enough diluent is added to make the product of definite strength. Of this, mention will be made when we consider strength of extracts.

In many respects soft extracts are the least satisfactory of all the official preparations. Thus the phrase, "evaporate to pilular consistence," is rather vague, and the strength of the finished product is apt to be uncertain; not only when first made, but also because, on standing, the strength is apt to change by loss of some of the water the extract contains, the extract becoming hard and dry.

To prevent this, the pharmacopoeia permits the addition, when necessary, of 10 per cent. of glycerin to the extract which is to be kept of a pilular consistence.

A second factor in the uncertainty of the pilular extracts is the amount of extractive which is contained therein. By the word "extractive" is meant the soluble and inert constituents naturally residing in drugs, grouped, in most text-books of materia medica, as gums, starches, and sugars. These constituents are practically useless from a therapeutic standpoint, and could they be eliminated, the extract would be much stronger. The question of the quantity of the extractive found in the extracts depends entirely on the menstruum employed, one containing a large amount of water yielding a larger amount of extract than those of a strongly alcoholic nature.

The question of the appropriate menstruum for extracting the full strength of the drug without excess of inert matter has been carefully studied by the Committee on Revision of the Pharmacopoeia, and the menstruum directed by that standard is the one yielding the most satisfactory results. This menstruum should, therefore, be strictly followed. Yet there have been known unscrupulous manufacturers who deliberately deviate from the pharmacopoeial menstruum, adding more water than directed by that standard, in order that large amounts of extract may be obtained. In such cases, of course, an increased yield means a diminution in the active strength of the extract, and it behooves the pharmacist to purchase extracts only from those manufacturers who are known to be reliable.

Among the many constituents which are included in the word "extractive" are the mineral salts, found naturally existing in drugs, such as potassium chloride and sulphate. From many moist extracts on standing the salts crystallize, and such extracts, when rubbed up in making an ointment, are frequently found to be gritty. Whether the grittiness of such extracts is due to crystals or to the accidental mixture of fragments of glass in the container, can be proved by adding a few drops of water and rubbing with an ointment spatula. Should the grittiness dissolve, it shows that it was due to these natural salts; whereas if the grittiness remains after trituration, fragments of glass are indicated.

A third disadvantage in the use of soft extracts is purely pharmaceutic, and that is the inconvenience in handling a semisolid mass. Extracts, especially those of potent drugs, are frequently prescribed in small quantities, say from to grain. To weigh out the soft extracts it is necessary that the to grain be weighed on a piece of paper, and by the time the quantity is scraped off the paper and

off the spatula, there is frequently very little of the extract transferred to the medicine. It is hardly necessary to say that in weighing such extracts the quantity should be transferred to the paper from the container by means of a perfectly clean spatula, and the spatula cleaned before transferring the weighed portion of the extract into the mortar or other mixture with which it is to be combined. If the surface of paper on which the extract is to be weighed is moistened before "taring," the extract will not stick so closely. Still better is it to use oiled paper or parchment paper.

A fourth inconvenience connected with soft extracts is the uncertainty of the dosage of the extract, due to the uncertainty of the strength of this extract. The variability of the extract-strength is of a twofold character: first, different drugs yield vastly differing quantities of extracts. Thus, gum opium yields about half its weight of soft extract; extract of belladonna and extract of hyoscyamus. yield about one-fifth their weight of extracts, while extract of nux vomica is about ten times stronger than the drug from which it is obtained.

Hence it is seen that different drugs yield vastly different quantities of extract; not only this, but, worst of all, different batches of the same drug yield different quantities of extract; a very important factor in quality of drugs being the soil on which they have been raised, and particularly the season in which they are collected.

Therefore at their best soft extracts are inconvenient and unreliable, and the revision committee did well in directing that so many of the extracts of the present pharmacopoeia be powdered and of definite strength, and that the extracts from potent drugs be assayed.

Strength of Extracts.-As just mentioned, many of the extracts of the present pharmacopoeia are directed to be of definite strength. A list of these standardized extracts is here given:

The preservation of extracts should be a matter of more concern than is usually given the subject in the retail pharmacy. Soft extracts should be kept covered sufficiently tight to prevent undue evaporation; since this causes them to become hard, dry lumps. A capital way of keeping extracts is by placing the original containers in which they are obtained from the manufacturer in special extract jars, and thus each extract is protected from the dust.

Powdered extracts-especially those diluted with sugar of milkshould be kept in well-stoppered bottles in a dry place. In contact with moist air they absorb moisture and become sticky masses.

In such cases desiccation and subsequent pulverization will restore the extract to its original form.

Commercial extracts-usually prepared by evaporation in a copper vacuum pan-are frequently contaminated with copper. This can be detected by sticking a bright steel spatula into the jar of suspected extract and allowing it to remain over night. If copper is present, a coating of the metal will be found on the spatula in the morning.

SPECIAL NOTES ON OFFICIAL EXTRACTS
EXTRACTUM ALOES. Extract of Aloes.

Recipe.-Aloes, one hundred grammes..

Boiling Water, one thousand cubic centimeters.

100 Gm. 1000 Cc.

Mix the Aloes with the Boiling Water in a suitable vessel, stirring constantly until the particles of Aloes are thoroughly disintegrated, and allow the mixture to stand for twelve hours; then pour off the clear liquid, strain the residue, and evaporate the mixed liquids to dryness with the aid of a water-bath or steam-bath. Remarks. This extract is prepared by evaporating an aqueous infusion of aloes to dryness.

Dose.-125 milligrammes (2 grains).

EXTRACTUM BELLADONNÆ FOLIORUM.

donna Leaves.

Extract of Bella

Recipe.-Belladonna Leaves, in No. 60 powder, one thou

sand grammes.

Alcohol,

Water, each, a sufficient quantity.

1000 Gm.