1781. He shows the formation of carbonic acid gas, and the diminution of the oxygen of the air.

26. Memoir on the Vitriolization of Martial Pyrites. Mem. Par. 1777. Published, I believe, in 1781. He shows that during the process the oxygen of the air is absorbed.

27. On the Combination of the Matter of Fire with evaporable Fluids, and on the Formation of the elastic aeriform Fluids. Mem. Par. 1777. In this paper he lays down the doctrine that heat combines with bodies, and changes them into elastic fluids; a doctrine obviously founded on Dr. Black's theory of latent heat, though Dr. Black's name never occurs in the paper.

28. Experiments made by Order of the Academy on the Cold of the Year 1776; by MM. Bezout, Lavoisier, and Vandermonde. Mem. Par. 1777.

29. Memoir on Combustion in general. Mem. Par. 1777. In this essay, published in 1781, he gives us the first distinct account of his theory of combustion, and combats the Stahlian doctrine of phlogiston.

30. Analysis of the Water of the Dead Sea; by MM. Macquer, Lavoisier, and Sage. Mem. Par. 1778. Published, I believe, in 1782. The result of this analysis will be found in the first number of the Annals of Philosophy.

31. Experiments on a White Steatite, converted by Fire into an excellent Biscuit of Porcelain; by MM. Guettard and Lavoisier. Mem. Par. 1778.

32. Description of two Coal-Mines situated at the Foot of the Mountains of Voyes, the one in Franche Comté, the other in Alsace, with some Experiments on the Coal which they yield; by MM. Guettard and Lavoisier. Mem. Par. 1778.

33. General Considerations on the Nature of Acids, and on the Principles of which they are composed. Mem. Par. 1778. In this paper he lays down his doctrine, that all acids contain oxygen, and that oxygen is the acidifying principle.

34. Report made to the Academy on the Cold which may be extracted from the Ashes of Vegetables; by MM. Macquer, Cadet, Lavoisier, Baumé, Bouquet, and Cornette. Mem. Par. 1778. This report was read to the Academy on the 21st of August, 1779. It refuted the opinion advanced by Sage, and some other chemists, that the ashies of vegetables yielded a considerable quantity of gold.

35. Memoir on some Fluids which may be obtained in the aeriform State at a Temperature little superior to the mean Temperature of the Earth. Mem. Par. 1780. Published in 1784. These fluids are ether, alcohol, and water. The experiments are not satisfactory.

36. Second Memoir on the different Combinations of Phosphoric Acid. Mem, Par. 1780. Published in 1784.

37. Memoir on a particular Process for converting Phosphorus into Phosphoric Acid without Combustion. Mem. Par. 1780. Published in 1784. This is the method, by the action of nitric acid, at present so well known.

38. Memoir on Heat; by MM. Lavoisier and de la Place. Mem. Par. 1780. This is the well known memoir in which the quantity of heat evolved by different bodies when burnt, &c. was measured by means of the calorimeter.

39. Report made to the Royal Academy of Sciences on the Prisons, the 17th March, 1780; by MM. du Hamel, de Montigny, le Roy, Tenon, Tillet, and Lavoisier. Mem. Par. 1780.

40. Experiments on the Composition of Water. Mem. Par. 1781. Published in 1784. This paper contains the result of Lavoisier's experiments on the composition of water. It is particularly valuable, on account of the historical details which it contains. Among other facts, he mentions, that before he began his own experiments he had been informed by Sir Charles Blagden that the experiment had been already performed by Mr. Cavendish, who had ascertained that water is a compound of oxygen and hydrogen gas.

41. Experiments on the Decomposition of Water, showing that this Liquid is not a simple Substance, and pointing out a Method of obtaining Hydrogen Gas in abundance; by MM. Meusnier and Lavoisier. Mem. Par. 1781. Published in 1784; and read to the Academy on the 21st of April, 1784. The method used was to pass water through red-hot iron. The iron was oxidated, and abundance of hydrogen gas was evolved.

42. Experiments on the Electricity absorbed by Bodies during their Conversion into Vapour; by MM. Lavoisier and la Place. Mem. Par. 1781. Published in 1784.

43. Experiments on the Heat produced during the burning of different Combustibles. Mem. Par. 1781. Published in 1784.

44. Remarks on Scheele's Book on Fire and Air. Mem. Par. 1781. Published in 1784. These remarks are chiefly confined to the phenomena of calcination and combustion.

45. Observations on the Method of Illuminating Theatres. Mem. Par. 1781. Published in 1784.

46. Experiments on the Composition of the Acid called Fixed Air, or Calcareous Acid, and which I for the future shall call Carbonic Acid. Mem. Par. 1781. Published in 1784. This is another of the most important of Lavoisier's experimental essays. He determines the composition of carbonic acid with much industry; and the proportions which he assigns, 28 carbon and 72 oxygen, are probably as near the truth as any other results hitherto offered to the public. In this paper he distinguishes vital air by the term oxygen, which it at present bears,

This essay, together with one of Cavendish on the same subject, was the principal weapon employed to overturn the notion of phlogiston advanced by Mr. Kirwan.

47. Description of a Method to increase the Effect of Heat produced by Chemical Operations. Mem. Par. 1782. Published in 1785. This was by means of a steam of oxygen gas, a method now too well known to require any description here. Lavoisier describes the apparatus which he employed for the purpose.

48. Experiments on the Effect produced by a very high Temperature on the Precious Stones. This consists in a detail of the experiments made by means of the apparatus described in the preceding paper.

49. On the Union of Nitrous Gas with Common Air. This is a eudiometrical paper, in which Lavoisier endeavours to calculate from the mixture of nitrous gas and common air, and the diminution of bulk, the quantity of oxygen gas contained in common air. It is needless to observe that it is far inferior to Mr. Cavendish's paper on the same subject.

50. General Observations on the Solution of the Metals in Acids. Mem. Par. 1782. Published in 1785. This is another of the important dissertations by which Lavoisier established his theory. He makes use of the decomposition of water with great address and ingenuity. Indeed, I consider this as the most profound of all Lavoisier's essays. He commits occasional mistakes, but his reasoning on the whole is accurate.

51. Experiments on the Precipitation of one Metal by another. Mem. Par. 1782. Published in 1785. This is also a very curious paper. He gives the true theory of these precipitations, and endeavours from them to determine the proportion of oxygen which unites with the different metals. Though all his results are wrong, his table is still curious, as it exhibits the first attempt to determine this very important point.

52. On the Affinity of Oxygen for the different Bodies with which it can unite. Mem. Par. 1782. Published in 1785, This may be considered as a kind of treatise on affinity. Considerable ingenuity is displayed in determining the affinity of different bodies for oxygen; and though the table given is not accurate, it constituted a valuable groundwork for succeeding experimenters.

53. On the Combination of Oxygen with Iron. Mem. Par, 1792. Published in 1785. These elaborate experiments cannot be considered as very successful.

54. On the Nature of the elastic Fluids disengaged during the Fermentation of Animal Substances. Mem. Par. 1782. Published in 1785. The chief gas obtained during his experiments was carbonic acid gas.

55, New Observations on the Increase of Weight which

Sulphur and Phosphorus undergo when burnt. Mem. Par. 1783. Published in 1786.

56. Remarks on Phlogiston. An Exposition of the Theory of Combustion and Calcination made known in 1777. Mem. Par. 1783. Published in 1786. This is a full exposition of his own theory, and a refutation of the Stahlian theory. By this time Lavoisier had been joined by Berthollet and Fourcroy, and had formed the design of propagating his opinions.

57. Experiments on the Effect of a Fire supported by Oxygen Gas on the Weight and Fusion of Mineral Bodies. This is a continuation of a subject already begun in a preceding paper.

58. Memoir on the Manufacture of Saltpetre. Ann. de Chim. xv. 225. It is generally believed that Lavoisier was mistaken in his opinion respecting the great quantity of saltpetre volatilized during the boiling of the ley.

59. Result of some Experiments on Agriculture, and Reflections on their Connection with Political Economy. Ann. de Chim. xv. 297.

These are all the papers of Lavoisier with which I am acquainted. It is probable, considering the dreadful period during which he terminated his career, that he may have published others with which I am unacquainted. His Essay on the Chemical Nomenclature, and his Elements of Chemistry, are too well known to require being particularized. I do not notice the posthumous volume of his essays published about six years ago in Paris by his widow, because I have never had an opportunity of seeing the book. It is chiefly historical, and will be more curious by determining the objects which Lavoisier aimed at, than the dates of his speculations, which are sufficiently determined from his original publications.

ARTICLE II.

Experiments on the absolute Magnetic Declination, and on the Amount of the Horary Variations of Needles in the same Place and Time, according as the Magnetic Fluid is differently distributed in their Interior. By Dr. Schübler; of Stuttgardt.*

THE following experiments were made with simple needles, three or four feet in length, suspended by a fine silk thread, in

* Translated from the Journal de Physique for September, 1812, vol. lxxv. p. 173. I have been induced to translate this paper by the singularity of the results which it exhibits. Though far from convinced of their accuracy, I think they are entitled to a careful repetition, in order to ascertain whether the state of the needle itself has any effect upon the daily variation.

an apparatus which screened them from the action of the air. The magnet which communicated to them the magnetic virtue was in the shape of a horse-shoe, and usually weighed about four pounds.

Exper. I.

I took a new needle, on which no magnetic experiments had been made, and converted it into a magnet in the ordinary way, by the double and single touch. It exhibited the small horary variations of the ordinary needle. I took a second needle, perfectly similar to the first; but instead of communicating to it magnetism in the usual way, I placed the south pole of the magnet on the middle of the needle, and drew it ten times to one of the ends of the needle without returning back again. I then drew it in the same way ten times towards the other end; and then by means of a small sensible needle determined the poles of this long needle, to which magnetism had been communicated in the peculiar way just described. Its two ends were north poles; the middle was a south pole (as might have been foreseen from the manner of communicating the magnetic virtue). A more attentive examination presented the following disposition of its magnetism :

-m

+ m

+m

This needle underwent a daily variation of 40 or 50 minutes, and even of 60 minutes, when the sky was serene; while an ordinary needle varied only 10 or 12 minutes per day. In February it moves towards the east at nine in the morning, and in the beginning of April at half past seven in the morning. It moves towards the west between two and three in the afternoon, and with such rapidity as to alter 8 or 10 minutes in an hour. From three to nine it inclines again towards the east, and then returns again towards the west. Hitherto I have observed these variations to be greatest when the sky is serene, and smallest when cloudy or rainy. I have repeated the experiment with various needles treated in the same way, and have always obtained the same declination.

Exper. II.

I took another needle similar to the former. I placed the south pole of the magnet upon its middle, and drew it ten times to the extremity of the needle inclined towards the north, while the other half of the needle remained untouched. This, of course, was the same kind of operation as the preceding. The needle, as before, exhibited great daily oscillations. An attentive