mouth bottle, holes being bored in the cork for the insertion of the tubes to which the rubber tubing is attached.

E, shows the perforated diaphragm of the percolator. With this simple arrangement percolation or filtration can be carried on for any length of time without exposure or loss by evaporation.

WATER-BATH PERCOLATION.

The process of water-bath percolation consists in subjecting the powder contained in a percolator* surrounded by water, to the action of a warm menstruum during the entire process of maceration and percolation. By the means of the waterbath the menstruum and powder are kept at any desired degree of heat for any length of time.

It is claimed for this process, that the heat employed is of great aid in effecting the solution of the soluble constituents

*The process of water-bath percolation as applied to pharmaceutical preparations and the apparatus,

FENNER'S WATER-BATH PERCOLATOR AND STILL,

were patented February 7, 1882.

The process is an application of the well known fact that a heated menstruum dissolves the soluble portions of drugs much more readily and to a much greater extent than the same menstruum when cold.

The apparatus is constructed with the view of serving its purpose in the best possible manner, and since its introduction it is coming rapidly into use in all parts of the country.

The following is a description and sectional view of the apparatus.

d

B

A.

MossENGCONY

It consists of a Percolator, A, suspended in a water-bath and connected externally by a stop-cock through which the percolate is received, and a Still, B, which may be adjusted whenever it is needed.

The percolator A, is also the vessel into which liquids are put for evaporation and

distillation.

The percolator may be removed by unscrewing the stop-cock at b, and lifting it out of the water-bath. It should be removed after using in order to dry the apparatus. The perforated diaphraghm at prevents the drug packing in the neck of the percolator and thereby hindering percolation.

The flow of the percolate can be regulated by the stop cock; it also serves to draw off the residue after distillation or evaporation. The vessel surrounding the Percolator is designed for water, which is to be heated when desired, forming a water-bath for the Percolator and its contents.

of the substance or substances which are being exhausted, and therefore, that it is much more rapid, efficient and economical than the ordinary method of percolation.

By consulting the solubility tables, which may be found in the pharmacopoeia and other standard works, it will be seen that the medicinal principles of vegetable drugs (especially the alkaloids and other substances in which their value chiefly consists), are from several to several hundred times more soluble in boiling water or alcohol than in cold. Although the heat employed in water-bath percolation is seldom so high as boiling alcohol or water, yet the solubility of the medicinal principles is relatively increased according to the heat employed; and, as the object of percolation is to exhaust the drug of its soluble medicinal agents no other argument than this for the application of heat during percolation seems necessary, for it is evident that the value of the drug is much more faithfully represented in preparations made in this manner, and, that in making fluid or solid extracts, or other concentrated preparations a much less quantity of menstruum is required to exhaust the drug, than when cold percolation is employed.

As the question may be asked by many if heat does not

The Still B, can be adjusted when desired, by setting its rim into the circular vessel surrounding the top of the water-bath and pouring a little water into the circular vessel, which forms a water seal or joint which prevents the escape of the steam. The vapor rises to the inner surface of the cone of the Still, is condensed by the cold water on the outer surface of the cone, and the distillate is discharged in the form of a liquid at a, being conducted through a rubber tube to any convenient receptacle. The following cut represents the Water-bath Percolator and Still detached, and in use as a percolator. When used for distilling, the cover of the percolator is to be removed and the still top adjusted as heretofore described. When used for evaporating, the cover of the percolator is to be removed, and the evaporation conducted in the ordinary way.

The water bath percolator can be used as readily for cold percolation as for warm, and, in short, when all things are considered it is the most serviceable, economical and convenient percolator in use.

These Water-bath Percolators and Stills are now being used to a large extent in all parts of the country, and the reports received from parties who have thoroughly tested them are very flattering.

At no distant day the process of water-bath percolation is bound to supersede the ordinary method of percolating as completely as percolation, when it was introduced, superseded the process of maceration.

injure the preparations, it may be here stated that the degree of heat directed cannot be injurious, as it is insufficient to volatilize any of the medicinal principles of the drugs.

The method of conducting water-bath percolation is as follows:

The powdered drug is to be moistened with a portion of the menstruum and either packed in the percolator at once, or after macerating twenty-four hours, as the formula may direct. A certain quantity of menstruum (as directed in the formula), is then to be poured upon the drug and it is allowed to macerate for a specified time, in a warm place. It is then to be heated (as directed in the formula) for a certain length of time and the percolation then begun and continued until the drug is exhausted, or until the required amount of percolate is obtained.

The same general directions for packing the percolator, keeping the drug covered with the menstruum, regulating the flow of the percolate, etc., as are specified in the officinal process, should be observed.

In the formulæ contained in this book for making preparations by water-bath percolation it is directed after packing in the percolator and adding menstruum to the drug, to "set in a warm place" for a certain length of time to macerate; by this it is meant that the percolator and its contents should be heated from 30° to 35° C. (86° to 95° F.) by any convenient means. In summer a warm place in the store will suffice, in winter a shelf by the stove or other heating apparatus will do; or, a box with a hinged door and holes in the bottom about the size of the bottom of the percolators, may be fastened to the side of the wall and the heat may be maintained by a coal oil lamp placed beneath the percolator.

In large establishments warming closets heated by steam pipes or other means may be arranged. It is not absolutely necessary that heat should be maintained during maceration, but better results will follow if it is.

The direction in the formulæ "heat very moderately" means that the temperature should not be higher than from 40° to 45° C. (104° to 113° F.); "heat moderately" means that the temperature should not exceed 60° to 65° C. (140° to 149° F.)—a higher temperature than this is seldom neces

sary.

After the percolation is concluded, if sufficient Alcohol is retained in the drug to be of value, it may be recovered by distillation. The amount of alcohol or other menstruum retained varies with the nature of the drug, from one-fourth to more than its entire original weight. In making any con

siderable quantity of a preparation, it is important to save this menstruum, which would otherwise be wasted, by distillation, as stated, in the article on distillation.

WASHING PRECIPITATES.

The object of washing fresh precipitates is to free them from soluble salts, or other substances with which they are associated, which are soluble in water.

The usual manner of washing fresh precipitates, in a small way, is to pour them upon a wet muslin strainer and filter water through them until the soluble matter has all been washed out.

This method is open to several objections: 1st, exposure to the atmosphere, which rapidly oxidizes many salts, especially the iron salts, rendering them insoluble; 2d, waste, as considerable of the precipitate is washed away by this method; 3d, inconvenience, as it requires the continued attention of the operator.

Another method is to wash the precipitate in a large jar or earthenware crock, by pouring upon it a quantity of water and stirring thoroughly, then allowing the precipitate to settle, drawing off the supernatant fluid with a syphon, pouring on more fresh water and thus continuing until the soluble matter is washed out; and then draining the precipitate upon a muslin strainer.

The best method, however, is to make the precipitate in a tall jar or crock, filled full of water; then, having fastened a piece of rubber tubing to each end of a stick, insert it in the jar in such a manner that a stream of water passing through one rubber tube will reach to the bottom of the vessel, while the water at the top of the jar will be carried off by means of the other tube, which acts as a syphon. The water to wash the precipitate can be supplied from a water-pipe, or from a bucket set above the washing apparatus, into which the tube is inserted as a syphon

It will be seen that by this means the precipitate is continually washed, and that it is not exposed, nor wasted, as only clear water is drawn off at the top of the jar, because, the precipitate has time to settle away from the surface of the water where the waste tube is attached. Precipitates are rapidly and thoroughly washed by this method.

WORKING FORMULE.

In presenting the Working Formula which follow to the consideration of American Pharmacists it is only necessary to state that they have been compiled and written for the purpose of making clearer the difference between the former and the present standard the Pharmacopoeia- and also for introducing new and improved formulæ and methods.

Druggists who are unaccustomed to making their liquid preparations by parts and weight, as the new Pharmacopoeia directs, find the present formulæ quite annoying, and often throw the authority aside, because it is too much trouble to "figure it out. " In the formula which follow, therefore, the old method of definite weight and measure, with which druggists are most familiar, is generally retained, and, as comparisons are usually made for the same quantity of finished preparation, the druggist may see at a glance the exact difference between the former and the present standard. The convenience of having both the former and the present formulæ together for comparison or use, cannot but be appreciated by druggists; for it will be many years before the preparations of the new revision are all adopted, and those of the old discarded; and constant reference to both standards will be required.

In regard to the departure from officinal methods and formula which appear in many preparations, it may be stated, that no changes have been made, nor new features introduced which have not been proven, by repeated trials, superior to the processes or formulæ of the Pharmacopoeia; and, as it is the privilege of every pharmacist to make his preparations in the most convenient, serviceable, and economical way, provided the standard of strength is maintained, no apology is offered for their introduction.

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