| Specific heat. | |
| Water | 1 |
| Sheet-iron | 0·109985 |
| Glass without lead (crystal) | 0·1929 |
| Mercury | 0·029 |
| Quicklime | 0·21689 |
| Mixture of 9 water with 16 lime | 0·439116 |
| Sulphuric acid of 1·87058 | 0·334597 |
| 4 sulphuric acid, 3 water | 0·603162 |
| 4 sulphuric acid, 5 water | 0·663102 |
| Nitric acid of 1·29895 | 0·661391 |
| 9⅓ nitric acid, 1 lime | 0·61895 |
| 1 saltpetre, 8 water | 0·8167 |
Their experiments were inconsistent with the conclusions drawn by Dr. Irvine, respecting the real zero, from the diminution of the specific heat, and the heat evolved when sulphuric acid was mixed with various proportions of water, &c. If the experiments of Lavoisier and Laplace approached nearly to accuracy, or, indeed, unless they were quite inaccurate, it is obvious that the conclusions of Irvine must be quite erroneous. It is remarkable that though the experiments of Crawford, and likewise those of Wilcke, and of several others, on specific heat had been published before this paper made its appearance, no allusion whatever is made to these publications. Were we to trust to the information communicated in the paper, the doctrine of specific heat originated with Lavoisier and Laplace. It is true that in the fourth part of the paper, which treats of combustion and respiration, Dr. Crawford's, theory of animal heat is mentioned, showing clearly that our authors were acquainted with his book on the subject. And, as this theory is founded on the different specific heats of bodies, there could be no doubt that he was acquainted with that doctrine.
16. In the Mem. de l'Académie, for 1780, occur the two following memoirs:
Report made to the Royal Academy of Sciences on the Prisons. By Messrs. Duhamel, De Montigny, Le Roy, Tenon, Tillet, and Lavoisier.
Report on the Process for separating Gold and Silver. By Messrs. Macquer, Cadet, Lavoisier, Baumé, Cornette, and Berthollet.
17. In the Mem. de l'Académie, for 1781, we find a memoir by Lavoisier and Laplace, on the electricity evolved when bodies are evaporated or sublimed. The result of these experiments was, that when water was evaporated electricity was always evolved. They concluded from these observations, that whenever a body changes its state electricity is always evolved. But when Saussure attempted to repeat these observations, he could not succeed. And, from the recent experiments of Pouillet, it seems to follow that electricity is evolved only when bodies undergo chemical decomposition or combination. Such experiments depend so much upon very minute circumstances, which are apt to escape the attention of the observer, that implicit confidence cannot be put in them till they have been often repeated, and varied in every possible manner.
18. In the Memoires de l'Académie, for 1781, there is a paper by Lavoisier on the comparative value of the different substances employed as articles of fuel. The substances compared to each other are pit-coal, coke, charcoal, and wood. It would serve no purpose to state the comparison here, as it would not apply to this country; nor, indeed, would it at present apply even to France.
We have, in the same volume, his paper on the mode of illuminating theatres.
19. In the Memoires de l'Académie, for 1782 (printed in 1785), we have a paper by Lavoisier on a method of augmenting considerably the action of fire and of heat. The method which he proposes is a jet of oxygen gas, striking against red-hot charcoal. He gives the result of some trials made in this way. Platinum readily melted. Pieces of ruby or sapphire were softened sufficiently to run together into one stone. Hyacinth lost its colour, and was also softened. Topaz lost its colour, and melted into an opaque enamel. Emeralds and garnets lost their colour, and melted into opaque coloured glasses. Gold and silver were volatilized; all the other metals, and even the metallic oxides, were found to burn. Barytes also burns when exposed to this violent heat. This led Lavoisier to conclude, as Bergman had done before him, that Barytes is a metallic oxide. This opinion has been fully verified by modern chemists. Both silica and alumina were melted. But he could not fuse lime nor magnesia. We are now in possession of a still more powerful source of heat in the oxygen and hydrogen blowpipe, which is capable of fusing both lime and magnesia, and, indeed, every substance which can be raised to the requisite heat without burning or being volatilized. This subject was prosecuted still further by Lavoisier in another paper inserted in a subsequent volume of the Memoires de l'Académie. He describes the effect on rock-crystal, quartz, sandstone, sand, phosphorescent quartz, milk quartz, agate, chalcedony, cornelian, flint, prase, nephrite, jasper, felspar, &c.
20. In the same volume is inserted a memoir "On the Nature of the aeriform elastic Fluids which are disengaged from certain animal Substances in a state of Fermentation." He found that a quantity of recent human fæces, amounting to about five cubic inches, when kept at a temperature approaching to 60° emitted, every day for a month, about half a cubic inch of gas. This gas was a mixture of eleven parts carbonic acid gas, and one part of an inflammable gas, which burnt with a blue flame, and was therefore probably carbonic oxide. Five cubic inches of old human fæces from a necessary kept in the same temperature, during the first fifteen days emitted about a third of a cubic inch of gas each day; and during each of the second fifteen days, about one fourth of a cubic inch. This gas was a mixture of thirty-eight volumes of carbonic acid gas, and sixty-two volumes of a combustible gas, burning with a blue flame, and probably carbonic oxide.