Every substance, whether it be regarded generally as forming a part of the mass of this globe, or particularly as an object of science, may be arranged in one or other of the three following classes: Solids, Fluids, and Gaseous Bodies. We shall now examine each of these classes separately, and endeavour to describe the constitutions and combinations of the substances composing them, which are objects of pharmacy.

I. Solids

Solid bodies are masses of minute particles combined and held together by the attraction of aggregation or cohesion. The arrangement of the particles with regard to one another is often such as to produce regular figures, in which case the solids are said to be crystallized. Cohesion and crystallization have been already considered.

Constitution Of Solids

Arrangement of the principal Solids, as Jar as regards Pharmaceutical Substances.

I. Simple Or Undecompounded

Carbon. Sulphur.

Phosphorus. Boron.

Iodine. Metals.

II. Compounds

Sulphurets of Metals. Oxide of Phosphorus. Iodides. Charcoal. Metallic Oxides.

------------------- with Acids.

Alloys. Earths.

with Earths.

Earths with metallic Oxides.

---------------fixed Alkalies.

Solid Acids.

Salts and Hydrosulphurets.

Bitumens, solid Oils.

Soaps.

Most vegetable Substances.

Many animal Substances.

Simple Solids

a. Carbon. The diamond is carbon in a state of purity; and although charcoal, in its ordinary state, almost invariably contains either hydrogen or water, yet, from the experiments of Tennant, confirmed by those of Messrs. Allen and Pepys, it is probable that charcoal is essentially as pure carbon as the diamond, and that the hydrogen it evolves depends on water, which it always absorbs on the shortest exposure to the air. It has the power of absorbing many gases, for which it has no chymical affinity. Carbon is a constituent of almost all vegetable and animal substances. The equivalent of carbon is = 6.12.

1 In drawing up this section, I have borrowed very freely from the third book of Thomson's System of Chymistry.

b. Sulphur. A brittle, greenish yellow, volatile solid, odorous when rubbed, nearly tasteless, having a sp. gr. 1 .99. It forms a hydrate with water, from which it cannot be wholly freed. It fuses at 216°, and at 300° powerfully attracts oxygen. The equivalent of sulphur is = 16.1. For its properties, see Part II.

c. Phosphorus is semitransparent, when pure, almost colourless, but generally of a yellowish red or amber colour, and a waxy consistence. Its specific gravity is 1.770. It is nearly insoluble in water, and is so soft that it may be cut with a knife. It is brittle at a temperature under 32°. Above that point it softens, and under 90° is very ductile. It fuses at 108°; in close vessels is volatilized at 219°; and boils at 550°. Exposed to the air at common temperatures, it undergoes slow combustion, and emits a white smoke, which is luminous in the dark, has an alliaceous odour, and condenses to an acid. It is obtained from urine, bones, and other animal matters.1 The equivalent of phosphorus is =15.7.

d. Boron is obtained from the decomposition of boracic acid, in the form of powder, of a deep olive colour, insipid, inodorous, and insoluble in water, alcohol, ether, and oils. It undergoes no change at any temperature, when heated in close vessels; but takes fire and burns like charcoal, when heated in the air to about 600°. During combustion it attracts oxygen, and is converted into boracic acid. It is also converted into that acid by decomposing nitric acid, when it is treated with it. Its equivalent is =l0.9.

e. Iodine is obtained in the form of crystalline, blackish-blue scales and plates, having a metallic lustre, soft and friable; sp. gr. 3.0844; it fuses at 225° Fahrenheit, and boils at 347°: its vapour is of a rich violet colour; its taste acrid; its odour similar to that of chlorine diluted in air : it is very soluble in alcohol and ether : scarcely in water. It gives a blue colour to starch. Its equivalent is = 126.3.1 f. Metals are simple inflammable bodies, of various specific gravity, density, and opacity; and, as the results of these qualities, possess great brilliancy or lustre from their power of reflecting almost all the light which falls upon their surface. Their colours are, generally, shades of white, grey, or yellow: their hardness is considerable; and, according to its degree, they are more or less elastic. One metal only, Mercury, is in a fluid state at the ordinary heat of the air. Many metals possess considerable tenacity, and are consequently malleable and ductile; but some are extremely brittle. They are sapid and odorous when heated or rubbed; their fracture is generally hackly; their texture fibrous or foliated; and many of them are sonorous. They are excellent conductors of caloric, electricity, and galvanism.

When exposed to the action of caloric, they expand and are melted; but differ greatly with regard to fusibility. Some of them are volatilized at known temperatures; while others are fixed at every known temperature. When fused, their surface is convex and globular; and in cooling, they generally crystallize. They are very susceptible of oxidizement. The following metals or their compounds are used as pharmaceutical agents:-

1 For experiment, the simplest mode of obtaining phosphorus is to mix a solution of phosphate of soda with a solution of acetate of lead, in the proportion of one part of the former salt to one quarter of the latter. This will yield a precipitate of phosphate of lead, from which phosphorus may be obtained by distillation. Henry's Elements of Chymistry, vol. ii. p. 7.

I. Malleable

1. Silver. (See Part ii.)

2. Mercury. {Ibid.)

3. Copper. (Ibid.)

4. Iron. (Ibid.)

5. Tin. (Part ii.)

6. Lead. (Ibid.)

7. Zinc. (Ibid.)

8. Potassium is obtained by decomposing pure carbonate of potassa, by means of charcoal. It has the metallic lustre of silver, is soft and malleable at 50°, but at 32° is hard and brittle. Its sp. gr. at 60° is 0.865. It becomes somewhat fluid at 70°, quite fluid at 150°, and at a red heat is converted into vapour. It combines rapidly with oxygen, and forms potassa. Its equivalent is =39.15.

9. Sodium, obtained by decomposing soda, has the lustre of lead, is very soft and malleable at 60°, and retains these properties at 32°. Its sp. gr. is 0.972. It fuses at 200°; and requires a higher temperature to be volatilized than potassium. It combines rapidly with oxygen, and forms soda. Its equivalent is = 23.3.

Turner

10. Calcium, obtained from lime, is yet imperfectly known. Combined with oxygen it forms lime. Its equivalent is = 20.5.

11. Barium, obtained by decomposing baryta, is a metal of a dark grey colour, with a lustre approaching to that of cast iron; it fuses at a low heat, but is not volatilized in a heat capable of melting plate glass. Combines rapidly with oxygen, and forms baryta. Its equivalent is = 68.7.

12. Magnesium is a solid metal. Little is known of its properties; it burns with brilliancy in oxygen gas, and is converted into magnesia. Its equivalent is = 12.7.

13. Aluminium is procured from chloride of aluminium, in the form of a grey powder. When heated to redness in the air, it burns, and is converted into alumina. Its equivalent is = 13.7.

II. Brittle And Easily Fused

1. Bismuth. (Part ii.)

2. Antimony. (Ibid.)

3. Arsenic. (Ibid.)

III. Brittle And Difficultly Fused, 1. Manganese. (Part II.). Compounds

a. Compounds of sulphur.

1. Sulphurets of Metals are compounds of sulphur and metals, often possessed of metallic brilliancy, opaque, and brittle. They are conductors of electricity. Four of them only are officinal.

Table Of Officinal Sulphurets Of Metals

Officinal. Sulphuret of potassium. (Part ii.) 2. Hydrosulphurets are solutions of the sulphurets in water, which are decomposed by the atmosphere and acids.

b. Compounds of Phosphorus.

1. Oxide of Phosphorus, produced on phosphorus when it is kept under water, in the form of white film; and also, by heating phosphorus in highly rarified air, when it assumes the form of red flakes, which take fire when slightly heated, and burn with a very vivid flame. By further exposure to the air they attract moisture, and are converted into an acid.

c. Charcoal? (Part ii.) d. Metallic compounds.

1. Alloys are compounds of two or more metals. They have generally lustre, hardness, tenacity, ductility, and other properties of the metals; but these properties in alloys differ from those of the metals from which they are formed. The compounds of mercury with other metals are named amalgams.

2. Metallic oxides are generally in the form of powders, or friable fragments, not at all resembling the metals; sometimes laminated and crystallized; of various colours, determinate with regard to the metals and their treatment; heavier than the metals; and refractory, or fusible into glass. Some are insipid, others acrid and styptic. In general they are insoluble in water, and combine with acids, or with alkalies, or with both at the same time. They are reducible by light, caloric, hydrogen, carbon, oils, &C.1

3. Metallic sulphurets.

4. Metallic iodides.

5. Metallic cyanides.

6. Earths. (Part iii.) Earths with earths. ---------------alkalies.

e. Solid acids and salts, in a crystallized state, contain a portion of water in their composition. The following are objects of pharmacy, or officinal:-

1. Phosphoric acid is solid, colourless, transparent, and resembles glass in appearance, but, more usually, it is some what opaque, or resembles enamel; is inodorous, very acid, reddens vegetable blues, and deliquesces when exposed to the air. Its specific gravity in a state of dryness is 2.687. It is very soluble in water, dissolving with a hissing noise; but, nevertheless, much heat is not evolved. It is decomposed at a high temperature by hydrogen, charcoal, and several of the metals. The composition of phosphoric acid is 31.4 or 2 eq. of phosphorus, and 40 or 5 eq. of oxygen. Equivalent = 71.4. It is officinal in its diluted state. (Part iii.)

1 As the same metal is susceptible of different degrees of oxidizement, it has been found necessary to designate the oxides thus formed by distinct appellations, indicative of the comparative quantity of oxygen with which the metals thus formed are combined. The terms protoxide, deutoxide, tritoxide, and peroxide imply that a metal is in its first, second, third, and ultimate stage of oxidizement.-These terms were proposed by Dr Thomson.

Phosphate of lime is found very abundantly in the native state. It constitutes the basis of bones, from which it is procured in the state of a white powder, by calcination and solution in muriatic acid, from which it is precipitated by ammonia. It is inodorous, insipid, and insoluble in water; soluble in an excess of phosphoric acid; decomposed by several of the acids. Exposed to a heat of 378o Wedgwood, it softens, and changes to an enamel. 100 parts contain about 71.4 of acid, and 28.5 of lime. Equivalent = 99.9.

Phosphate of soda. (Part iii.)

2. Boracic acid is obtained in the form of white, thin, irregularly hexagonal scales, greasy to the feel. It reddens vegetable blues, is inodorous, has a sour bitterish taste, and leaves a cooling sweet impression in the mouth. Its specific gravity is 1.479. It swells up when exposed to the fire, and melts into a hard transparent glass. Boiling water dissolves only two parts of boracic acid: alcohol dissolves it, and the solution burns with a green flame: oils also dissolve it with the assistance of heat. It oxidizes only iron, zinc, and perhaps copper. Its components are, 10.9 or 1 eq. of boron + 24, or 3 eq. of oxygen. Equivalent = 34 9.

Biborate of soda. (Part iii.)

3. Benzoic acid. (Ibid.)

4. Succinic acid. (Ibid.)

5. Oxalic acid, generally obtained by treating sugar with nitric acid, is in the form of white, transparent, shining, four and six sided prisms, which have a very acid taste, redden vegetable blues, and are soluble in their own weight of boiling water. The solution of one part of the acid in 3600 parts, by weight, of water, is perceptibly acid to the taste. Exposed to heat in open vessels, it is decomposed. The dry acid is a compound of 12.24, or

2 eq. of carbon, and 24, or 3 eq. of oxygen.1 Oxalic acid has been swallowed by mistake for Epsom salts, and has produced fatal effects in many instances. I was the first who ascertained, by experiments on dogs and rabbits, that it acts on the stomach like other corrosive poisons; and that a mixture of chalk and water is the best antidote.2 Equivalent = 36.24.3

6. Tartaric acid. (Part iii.) Tartrate of potassa. (Ibid.)

Variety. Bitartrate ofpotassa. (Part ii.) Tartrate of potassa and soda. (Part iii.)

7. Citric acid. (Ibid.) f. Bitumens. (Part ii.) g. Soaps. The true nature of these compounds has been illustrated by Chevreul. He found that the fatty matter they contain consists of two distinct substances, which he has named Stearin and Plain. These, by the action of salifiable bases, are converted into two acids, the margaritic and the oleic; and soaps are merely combinations of one or both of these acids, with alkaline, earthy, or metallic bases. 1. The alkaline soaps have a peculiar unpleasant odour and taste; form a milky solution with water, and a transparent one with alcohol; are powerfully detergent, and are decomposed by the earthy and the metallic salts. 2. The earthy soaps are insoluble in water, and not detergent. 3. Metallic soaps are likewise insoluble in water, but some of them are soluble in alcohol, and others in oil.