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What instruments may be used for cutting, slicing, or chopping? Pruning-knife, pruning-shears, tobacco-knife, or herb cutter. Half-round rasp.

What instrument for grating?

What for contusion? Iron pestle and mortar, or the pestle and mortar may be made of wood or marble.

What is meant by the terms Grinding and Pulverizing? ing means reducing substances to coarse particles.

ducing to fine particles.

Grind

Pulverizing means re

What is a Drug Mill? A mill for comminuting drugs.

Into what four general divisions are drug mills divided? Burr stone-mills, roller-mills, chaser-mills, and hand-mills.

Describe the principle of each. A burr-stone-mill consists of two disks of stone, rubbing together, the approximating faces being cut in grooves, to afford grinding surfaces.

Roller-mills consist of rollers revolving in opposite directions, the distances between them being regulated by screws. They operate by crushing, or cutting and crushing, and the rollers are made smooth, or with corrugations, serrations, undulations, or crenations, according to the nature of the drug which is to be operated on.

Chaser-mills consist of two heavy granite stones revolving on a circular granite base, surrounded by an iron curb. They operate by crushing and by the friction engendered by the outer edge of the stone traveling through a longer distance than the inner edge.

Hand-mills are divided into three classes, according to the arrangement of their grinding surfaces, which may be vertical, horizontal or conical. They are made of iron, with grinding plates of hardened iron or steel, and thumb-screws to regulate the distance between the grinding faces.

What is meant by Trituration? Rubbing substances to fine particles by means of a pestle and mortar.

Describe the process. Give the pestle a circular motion with downward pressure. Commencing in the centre of the mortar, work outward in ever increasing circles till the side of the mortar is touched, then reverse the motion and decrease the size of the circles till the centre is reached.

How should a pestle fit its mortar? See that the pestle has as much bearing on the interior surface of the mortar as its size will permit, to secure as much triturating surface as possible.

Of what substances are pestles and mortars for trituration composed? Wedgwood, porcelain, and glass.

What is a Spatula? A flexible steel blade fixed in a handle, and used for various purposes in pharmacy. In trituration it may be used to loosen up the substance when it becomes packed upon the sides of the mortar. The best form of spatula is that known as the balance handle.

How may the fineness of powders be regulated? By sieves of various construction, with meshes of different sizes, as required. It is important that all portions of the sifted powder be thoroughly mixed, in order to secure uniform composition.

Powders are known as very fine (sieve with 80 meshes to the linear inch); fine (60 m. to 1. i.); moderately fine (50 m. to 1. i.); moderately coarse (40 m. to 1. i.); coarse (20 m. to l. i.). These powders are also known by number, as Nos. So, 60, 50, 40, and 20, respectively. Iron

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wire, brass wire, bolting cloth, and horse hair are the materials usually chosen for sieves.

What is Levigation? "The process of reducing substances to a state of minute division by triturating them after they have been made into paste with water or other liquid." A slab and muller is the apparatus used for this process. When this is constructed of porphyry, the process

is termed porphyrization.

What is Elutriation? If an insoluble powder be suspended in water the heavier particles will precipitate first. By decantation of the liquid, the finer portions may be separated. Prepared chalk is a familiar example. The process of making the pasty mass obtained by elutriation into little cones is called TROCHISCATION. A tinned iron cone, with a handle, is used for this purpose. The handle has a short leg in the centre, which is tapped gently on a slab, upon which the substance forced through the aperture at the bottom of the cone by the shock falls, in the form of a little conical mass. Successive shocks are employed, and the resulting conical masses deposited in this manner on the slab soon dry, the moisture being absorbed by the slab.

What is meant by Pulverization by Intervention? The process of reducing substances to powder through the use of a foreign substance, from which the powder is subsequently freed by some simple method. Ex. Camphor may be powdered with the aid of a few drops of alcohol. The foreign substance is freed from the powder by subsequent evaporation.

SOLUTION.

What is Solution? The permanent and complete incorporation of a solid or gaseous substance with a liquid. The product is called a solution, the liquid used a solvent, and if the solvent will dissolve no more of the substance, the product is called a saturated solution.

What is the difference between simple and chemical solution? In simple solution no change occurs in the chemical structure of the dissolved substance (sugar in water); but in chemical solution the reverse is the case. Ex. The official solution of nitrate of mercury,

How may solution of solids be facilitated? By pulverizing the substance the extent of surface exposed to the solvent is increased, and by agitation the frequency of the contact is augmented, thus favoring the rapidity of solution. Heat, by causing convection currents in the liquid, facilitates solution, and as heat works against cohesion, it increases the solubility of the substance.

May saturated solutions be used as solvents? Yes; a liquid saturated with one substance is still a solvent for another substance.

What effect has solution upon temperature? Simple solution lowers temperature; chemical solution raises temperature.

What is the best manner of effecting the solution of a solid ? Crush the substance in a mortar with the pestle, then pour on the solvent, continually stirring the mixture.

What is meant by Circulatory solution? If the substance be placed in a bag and suspended in the solvent, a current will be engendered by the sinking of the dissolved portion from the bag, its place being supplied by fresh portions of the solvent.

What solvents are used in pharmacy? Water, first in importance, then Alcohol, Glycerin, Ether, Benzin, Chloroform, Bisulphide of Carbon, Acid, and Oils, take their respective rank as solvents.

How would you effect the solution of a gas in water? Apparatus is so arranged that the gas first passes through a wash-bottle, by which it is purified, and then allowed to bubble up through the solvent, which absorbs a portion of it during the passage.

SEPARATION OF FLUIDS FROM SOLIDS. Name some of the processes for separating fluids from solids. Lotion, Decantation, Colation, Filtration, Clarification, Expression, Percolation, etc.

What is meant by Lotion or Displacement washing? The process of separating soluble matter from a solid, by pouring a liquid upon it, which will dissolve and wash out the soluble portion. Ex. The washing of a precipitate in a funnel by means of a Spritz bottle.

Various automatic apparatus for continuing washing are described in works on pharmacy.

What is Decantation? Separating a liquid from a solid by pouring it off. This is sometimes better effected by a siphon.

Describe a Siphon. A siphon is an inverted U-tube, with one leg longer than the other. It is first filled with the liquid, and the shorter arm immersed in the liquid contained in the vessel, and a current established in this way: The column of liquid in the shorter arm is overbalanced by the column in the longer arm, thus causing a current to flow from the shorter to the longer arm, the shorter arm drawing a fresh supply from the vessel, which is thus finally emptied.

What is meant by Colation, or Straining? The process of separating a solid from a fluid, by pouring the mixture upon a cloth or porous substance, which will permit the fluid to pass through, but will retain the solid.

What material is used for constructing Strainers? Gauze, Muslin, Flannel, Felt, etc.

What is meant by Filtration? The process of separating liquids from solids, with the view of obtaining the liquids in a transparent condition. Filters are made of paper, paper pulp, sand, asbestos, ground glass, charcoal, porous stone, etc.

Into what two general classes are paper filters divided? Plain and plaited. Plain filters are used for retaining and washing precipitates; plaited filters for ordinary filtering operations.

How are paper filters supported?

In funnels.

What method is used for producing rapid filtration? Various methods are used, such as suction with the mouth, or by a column of falling water, to produce a partial vacuum beneath the filter, and thus hasten the process by increasing atmospheric pressure.

What is meant by Clarification? The process of separating from liquids, without the use of strainers or filters, solid substances which interfere with their transparency.

Describe the eight principal methods of Clarification.

1. By the Application of Heat.

Heat, by diminishing the specific

SEPARATION OF FLUIDS FROM SOLIDS.

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gravity of viscid liquids, permits the precipitation of the heavier particles, the lighter ones rising to the top. Boiling facilitates the separation, as the minute bubbles of steam adhere to the particles, and rise with them to form scum, which may be skimmed off.

2. By increasing the Fluidity of the Liquid. This may be done by diluting it with water. Owing to the diminished specific gravity, the heavier particles sink, and the liquid may then be decanted.

3. Through the use of Albumin. If albumin be added to the turbid liquid, and heat applied, on coagulating it will envelop the particles, and rise to the top with them. Skimming will remove the scum.

4. Through the use of Gelatin. Gelatin will form with tannin an insoluble compound, and where cloudiness is due to the presence of tannin, will clarify the liquid in this way.

5. Through the use of Milk.

Acids will precipitate the casein of milk. It is used in sour wines, etc., the precipitated casein carrying with it the insoluble particles.

6. Through the use of Paper Pulp. Agitate the liquid with the pulp and let it stand till clear; or throw the whole on a muslin strainer; the pulp will form an excellent filtering medium by partially closing the meshes of the linen.

7. By Fermentation. Many substances soluble in the natural juices of plants are insoluble in the dilute alcoholic solutions resulting when these juices are fermented and subside as deposits.

8. By subsidence through long standing. The deposit formed is called a sediment.

What is the difference between a Sediment and a Precipitate? "Sediment is solid matter separated merely by the action of gravity from a liquid in which it has been suspended. A precipitate, on the other hand, is solid matter separated from a solution by heat, light, or chemical action."

What is Decoloration? The process of depriving liquids or solids in solution of color by the use of animal charcoal.

How would you separate Immiscible Liquids? By the use of a pipette, a glass syringe, a separating funnel, or a Florentine receiver. A funnel with a stop-cock to stop the flow as soon as the heavier liquid has all passed through is called a separating funnel. A Florentine receiver, used in the distillation of volatile oils, differs from an ordinary receiver in having an overflow arranged to permit the escape of the condensed water while retaining the volatile oil.

What is meant by Precipitation? "The process of separating solid particles from a solution by the action of heat, light, or chemical substances." The solid particles separated are called the precipitate; the precipitate producer, a precipitant; and the liquid remaining, supernatant liquid. A precipitate may either fall or rise to the top of the supernatant liquid. The physical characteristics of precipitates are described by the words curdy, granular, flocculent, gelatinous, crystalline, bulky, etc. magma is a thick, tenacious precipitate. Precipitation by heat is illustrated by the coagulation and precipitation of albumin when albuminous fluids are heated; and the precipitation of silver salts by light illustrates precipitation by light; and precipitation by chemical reaction occurs in a

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large number of instances when making official chemical salts. Example: the preparation of Precip. Carb. Calcium.

What are the objects of Precipitation? Ist. A method of obtaining substances in the form of powder. 2. A method of purification. 3. A method of testing chemicals. 4. A method of separating chemical

substances.

Vessels of glass called precipitating jars are made. They are larger at the bottom than the top. Hot, dense solutions usually produce heavy precipitates, and the reverse is the case when dilute solutions are employed. Precipitates may be collected in a funnel on filtering paper or on strainers.

CRYSTALLIZATION.

What is Crystallization? The process of placing substances under the most favorable circumstances for them to assume certain inherent geometrical forms called crystals. Substances that will not crystallize are called amorphous. Crystallography is that department of knowledge devoted to crystals. The objects of crystallization are to increase the purity and beauty of chemicals.

1. MEANING OF TERMS.

Faces-the planes bounding a crystal.

Edge-the intersection of two contiguous surfaces.
Angle-the intersection of three or more faces.

Perfect crystal-a crystal in which the faces, edges, or angles have equal faces, edges, or angles opposite to them, and if the middle point of the opposite faces or edges or the opposite angles be joined by straight lines, the point at which these lines intersect will be the centre of the crystals.

Axes-the lines drawn through the centre of crystals.

Dimorphous, trimorphous, polymorphous, etc.—when the same body crystallizes in two or more forms belonging to different systems.

Isomorphous when different substances crystallize in the same form. Prismatic-crystals extended principally in the direction of their longer

axes.

Tabular-crystals with flat planes.

Lamina-crystals in the form of thin plates.
Acicular-needle-shaped.

Orthometric-those in which the three axes intersect at right angles.
Clinometric-those in which the axes intersect at oblique angles.

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2. SYSTEMS.

Six different systems of crystallization are recognized. The word system is used because every crystallizable body assumes its own characteristic form or some form directly derived from it by a single law,' so that several forms may belong to the same system.

I. Monometric or Regular.-The angles of equal length intersecting at right angles.

II. Dimetric or Quadratic.-Three axes, two equal, the other different in length, all intersecting at right angles.

III. Trimetric or Rhombic.-Three axes of unequal length intersecting at right angles.

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