a brittle, hard, yellow substance, semi-transparent like horn. It must have a near affinity to gelatine, for by the action of nitric acid it is converted into that substance; and it consists of the same ingredients, though probably in somewhat different proportions.

3. Fibrina is the solid or fibrous part of the animal muscles. It is prepared in the blood, from which it may be procured by washing the red clot which forms in blood, when the serum separates from it, till it has entirely lost its red colour. It It may also be obtained, by a similar process, from the muscles or flesh of animals. It is of a white colour, and has no taste or smell. When exposed to heat, it contracts and moves like a bit of horn, exhaling at the same time the smell of burning feathers. In a stronger heat it melts. It has a near relation to the two former bodies, for nitric acid converts it into gelatine. It appears also to be composed of the same ingredients, but it probably contains more carbon and nitrogen, and less of oxygen.

4. Mucilage seems to be only the weakest and most diluted form under which gelatine appears, and ought therefore to be referred to the same head.

5. Urea is the essential constituent of that secretion (urine) from which it derives it name.. It differs from all other animal substances in containing a larger portion of nitrogen.

6. Sugar has been found in animals in every

respect similar to the sugar of vegetables, and particularly in milk.

7. Oils, as to their general properties, have been treated of in the lecture on Combustibles. The animal oils are spermaceti, fat or tallow, train or fish oil, and butter. The first of these, spermaceti, is distinguished from all other oily bodies by the crystalline appearance it assumes. It is found in the skull of the spermaceti whale, and forms also a copious sediment in the oil of that animal.

8. Resins have also been already noticed. A resin is found in the bile of animals. Ambergris too is considered as an animal resin, being formed, as is supposed, in the stomach of the spermaceti whale. Castor, civet, and musk are also referred to this class.

9 and 10. Sulphur and Phosphorus are also found in animals.-The latter exhales copiously in putrefaction in the state of phosphuretted hydrogen gas, and often produces those luminous appearances in putrid fish, &c. so terrifying to old women and children.

11. The acids which have been detected in animal bodies are the phosphoric, sulphuric, muriatic, carbonic, benzoic, uric, rosacic, amniotic, oxalic, acetic, malic, and lactic.

12. All the alkalies have been found in the fluids of animals.

13. The only earths that exist in animal bodies are lime, magnesia, and silica.

VOL. II.

14. Of the metals, only iron and manganese have been found in animal bodies.

The parts of animals consist principally of the following matters :

1. Azote.

2. Carbon,

3. Hydrogen.

8. Soda.

9. Potass.

10. Muriatic acid.

The first six are so much more abundant than the rest that animal matter may be generally considered as composed of them; the first four constitute the soft parts, and the other two form the bases of the hard parts. Silica is only found in cases of disease.

INDEX.

A.

Acceleration, law of, explained, i. 217.

Acetic acid, its nature and properties, ii. 163, 164.
Acetous fermentation, simple process of, ii. 285.
Acids, canon of chemistry concerning their constitution,
ii. 43-their natures, kinds, and properties, 147 to 169.
Acids contained in waters, ii. 258.

Affinities, importance of the knowledge of, ii. 102.
Affinity (chemical,) or elective attraction, explained, ii.
96 to 100.

Astronomical day, commencement of the, ii. 14.
Air, properties of, i. 62—means of ascertaining its density,
66. 77 to 84-experiments to prove the elasticity of
the, 68 to 73-beautiful experiments to evince the
pressure of, 73 to 75-capable of being rarefied by
heat, 74-comparative density of the, 78-its degree
of expansion, being heated, ii. 61-compressibility of,
66. See also Atmosphere, and Pneumatics.
Air-furnaces, chemical heat procured by, ii. 120.
Air-gun, principle of this instrument, i. 77.
Air-pump, invention and explanation of, i. 68. ·
Albumen, what meant by, ii. 281-remarks on, 287.
Alcohol, or ardent spirit, chemical account of it, con-
sidered as a compound combustible substance, ii. 209-
curious phænomena produced by its mixture with dif-
ferent acids, 216, 217.

Alembic, form and use of the, ii. 110.
Almacanthers, what, i. 267.

Alkalies, simple substances in chemistry, ii. 36-chemical
account of them, 54—their natures, kinds, and pro-
perties, 140. 146 to 235.

Alkaline salt met with in water, ii. 259-found in mineral
waters, 265.

Alloys, nature of, ii. 249.

Altitude, what, i. 267.

Alumina, or alum, chemical account of it, considered as
one of the kinds of earths, ii. 182 to 186.

Ammonia, its nature and qualities, ii. 55. 144, 145.
Amphiscii, why so called, i. 266.

Amplitude, explanation of this term, i. 267.

Analysis, great progress which has been made in this ope-

ration by modern chemists, ii. 101,102.

Angle of incidence defined, i. 144.

Angular distance, what, i. 266.

Animal acids considered, ii. 166, 167.

Animal substances, different classes of them, ii. 286 to

290.

Animals, the component parts of, ii. 290.

Annular eclipses of the sun, when take place, ii. 22.
Antipodes, explanation of this term, i. 266.
Antœcii, the, i. 266.

-

Apparatus, chemical, lecture on, ii. 104-advantages and
disadvantages of vessels made of different materials, ib.
-forms of vessels for different purposes, 107-means of
producing heat, 111 constructions and objects of
furnaces, 117-lutes, 123—a large apparatus seldom re-
quired, 124.

Armillary sphere, the, defined, i. 268.

Artificial day, meaning of the term, ii. 9.

Asbestos, nature of the, ii. 194.

Ascension, right and oblique, and ascensional difference
explained, i. 267.

Assaying metals, process of, ii. 242.

Astronomy, lectures on, i. 250. 270. ii. 1. See Eclipses,
Seasons, Solar System, and Time.-Origin and dignity
of this science, i. 250-its history, 251-explanation of
the principal words and phrases used in it, 263.
Atmosphere, experiments to prove the weight and pressure
of the, i. 65,66-lecture on the phænomena of, 78-in-
quiry concerning its height, ib.-height of how calcu-