evaporation of water from hot coals, Messrs. Lavoisier and De la Place have remarked, that bodies passing from a solid or fluid state into vapour, give unequivocal signs of positive or negative electricity. A large vessel containing a quantity of iron filings was insulated and connected with M. Volta's condenser. Three parts of water and one of vitriolic acid were poured upon the filings, which caused a brisk effervescence, and a rapid discharge of inflammable air, and in a few minutes the condenser became so strongly charged that it gave a very sensible spark, and by the electrometer it was found to be negative. The production of fixed and nitrous airs had the same effect; also chafing dishes insulated and filled with lighted coal produced very clear signs of negative electricity after the combustion of the coal. It appears that in these experiments, the substances evaporated carry away from the vessels with which they are in contact a part of their natural electricity; but when water was poured upon red-hot iron pans, the electricity was no more negative, as in the former experiments, but decidedly positive. These experiments were communicated to the Academy of Sciences in the year 1781.

M. de Saussure has also tried many experiments of this kind by plunging hot iron and other metals in water, and pouring water into crucibles of iron, brass, copper, silver, or porcelain. Sometimes he used distilled water, also spirits of wine and ether, and in these experiments the electricity was sometimes positive, sometimes negative, and sometimes neither.

M. de Saussure thinks that when the operation which converts the water into vapour at the same time decomposes it, or the body with which it is in contact, it produces a new quantity of the electrical matter, and that the vessel used in the operation becomes positive, negative, or neither, according as the fluid produced is superior, inferior, or equal to that which is taken from the vessel by evaporation. An account of these curious experiments is contained in the second volume of M. de Saussure's Travels over the Alps, page 227.

The gold leaf electrometer being well adapted to the performance of experiments of this kind, I was induced to repeat some of them with variations, in hopes of new appearances and since almost every substance in the whole chemical nomenclature may thus be subjected to the action of fire, and its affinity with electricity in a state of vapour examined, new facts may yet arise which will produce new theories; therefore, the following experiments are placed in the order they were tried, without regard to system.

Experiment 1.-A bason of tinned iron about six inches wide at the bottom, and eight inches at the top, was placed upon the cap of a gold leaf electrometer. The bottom of the bason was covered with water about an inch deep. An iron chissel was heated red-hot, and dropped into the water, one end being immersed and the other resting on the edge of the vessel. The gold leaf gradually opened about an inch negatively, then closed and opened positively, remaining positive to the end of the experiment.

2. The chissel was heated more than in the last experiment, and the gold leaf struck the sides of the electrometer six times negatively; then it changed, and stood at half an inch positive to the end.

3. The chissel was again made very hot, and it caused the gold leaf to strike often negatively; after which it closed, but never opened positively.

4.--The chissel was heated very much by blowing the fire, and it caused the gold leaf to strike fourteen times negatively, but no positive electricity appeared. This was repeated about twenty times without any production of positive electricity.

5. Upon observing that the chissel was much calcined upon its surface, by being so frequently heated in the above experiment, I rubbed off the calx and heated it again, and found that now it produced first negative and then positive electricity, as before; whence it appeared that its production of positive electricity depended upon the metallic state of the iron.

6.-A large bar of copper and a piece of brass were heated redhot and plunged in the water, which also produced first negative and then positive electricity.

7.-Melted lead was dropped into water contained in the bason as above, which gradually opened the gold leaf positively.

It is,

8.-Melted lead being dropped into a deep narrow vessel almost full of water, did not electrify it, since it emitted no vapour. therefore, not the mere decomposition of the metal, but the formation of a certain kind of vapour, which excites electricity.

9.--Boiling mercury was dropped from an earthen crucible into a small quantity of water in a porcelain cup standing upon the cap of the electrometer, which caused the gold leaf to open positively.

10. Several thin pieces of bell metal were heated red-hot and dropped into the water, which caused a negative repulsion only.

11.-An earthen unglazed flower pot was half filled with red-hot cinders; then the other half was filled with chopped grass, which caused the gold leaf to open with positive electricity, and to continue striking the sides a considerable time. In the same manner were tried cabbage leaves, lettuces, turnip tops and roots, and chick weed, with the same results.

12. Turnings of dry ash wood were thrown upon the hot cinders as above, which smoked much without causing any repulsion of the gold leaf till water was added, which caused a strong positive elec.. tricity.

13.-Dry hay was burnt in the flower pot, as above, which produced no electricity till water was added, and then it became strongly positive.

14. The flower pot was placed upon the electrometer with redhot cinders alone, and water was dropped into the middle, which opened the gold leaf negatively; then, dropped near the side, openedit positively; again in the middle, negatively.

15.-Since the cinders became more positive and negative with

water only, I repeated the above experiments on green and dry vegetables with a red-hot earthen crucible, but without any difference in the result. A square piece of brick was first placed upon the electrometer, to prevent the heat from injuring it in this and all the subsequent experiments, in which red-hot bodies were to be placed upon it.

16.-A spoonful of salt was thrown into the red-hot crucible, which opened the gold leaf negatively; a second quantity was thrown in, and it became positive.

17. The crucible being again heated, two spoonfuls of salt were thrown in, which opened the gold leaf positively; then water was dropped into the middle of the salt, which changed its electricity to negative; then more water dropped near the side of the crucible opened the gold leaf positively; then again in the middle negatively.

18. Salt and water were mixed and dropped into the red-hot crucible, which caused a strong negative repulsion; then, after the water was evaporated, more was dropped in the middle, which renewed the negative repulsion till the water was dropped near the side, when it became positive. This change from positive to negative was often repeated.

19.-A small quantity of salt was thrown into the red-hot crucible, which caused the gold leaf to open negatively; then the salt remained till it was burnt black, and water being added, caused a strong positive repulsion.

20. The vitriolic and nitrous acids were severally dropped upon red-hot bricks, which opened the gold leaf positively. The bricks were tried before and after the experiments with water, which caused a negative repulsion.

21.-A large red-hot cinder was placed upon the electrometer, and olive oil dropped upon it, producing a copious smoke, but no electricity; then water was added, which opened the gold leaf negatively.

22.-Olive oil and water were shook together in a phial, and both poured upon a red-hot piece of cast iron about an inch thick, four inches broad, and five inches long, which opened the gold leaf strongly negative.

23.-Vitriolic and nitrous acid were dropped upon the cast iron, which opened the gold leaf positively.

24.-Dry hay was placed upon the cast iron, and pressed down by a stone placed upon it till it was burnt black; then water was added, which opened the gold leave positively. The hay was then brushed off, and more water dropped upon the iron, which caused the gold leaf to open positively till the surface was well cleaned and heated again, when it produced negative.

25.-A heap of wheat flour was placed upon the hot iron, which smoked without any electricity till water was added, which opened the gold leaf positively.

26.

Sand placed upon the hot iron, and water added, opened the gold leaf positively.

27.-Lump sugar placed upon the hot iron produced no electricity till water was added to the burnt residuum, which opened the gold leaf positively.

28.-Powdered charcoal was placed upon the hot iron, and water poured upon it opened the gold leaf positively; but when water was dropped upon a red-hot piece of charcoal, it caused a negative repulsion.

29.-Red and white port wine dropped upon the hot iron produced negative repulsion when the iron was so hot as to produce no electricity with water alone, which was tried before and after the wine.

30.-Raspberry wine dropped upon the hot iron produced positive electricity. The raspberry wine and red port were alternately dropped upon the same iron five or six times successively, which changed the electricity from positive to negative each time. Also several other sweet wines were tried, which, as well as sugar and water, produced positive electricity.

31.-Fresh urine poured upon the hot iron produced strong positive electricity.

32.-Milk poured upon the hot iron caused a strong negative repulsion; and even when water was added to the burnt residuum, except in some instances when it was burnt very black, it became weakly positive.

33.-Butter was burnt upon the hot iron, and water added caused a strong negative repulsion.

34. Ale produced no electricity till water was added to the burnt residuum, which became positive.

35.-Dry tea leaves were burnt upon the hot iron, and water added opened the gold leaf positively; also black pepper and tobacco. 36.-Soap first burnt on the hot iron, and then water added; also soap and water mixed produced a strong negative repulsion.

37.-Tin-foil was placed upon the hot iron, which soon melted; then water dropped upon it first opened the gold leaf negatively, then weakly positive.

38.-Alum burning on the hot iron produced no electricity till water was added to the burnt residuum, which caused a strong positive repulsion.

39.-Moist salt of tartar was thrown upon the hot iron, which caused the gold leaf to open strongly negative; its vapours condensed so quick upon the tube used for trying the electricity, that it was with some difficulty that it could be excited.

40.-Saliva produced positive electricity. When water alone was producing negative repulsion, spitting upon it would immediately change it to positive.

41.-Yeast was strongly positive, but not till water was added to the burnt residuum.

42.-Cotton and linen rags were burnt on the hot iron, and water added, produced a weak positive repulsion.

43.--Sheep's wool, feathers, and hair, were burnt on the hot iron, and when a single drop of water was added, the gold leaf struck the sides of the electrometer positively.

44.-Rasped horn and bone were burnt upon the hot iron, which produced positive electricity when water was added, but not near so strong as in the last experiment.

45.-Powdered pit coal was placed upon the hot iron, which produced positive electricity upon the addition of water.

46.-Fresh sheep's blood was dropped upon the hot iron, which produced positive electricity.

47.-A hollow piece of bell metal about an inch thick, and three inches diameter, was cast on purpose to repeat these experiments upon, most of which were again tried, but with no remarkable difference, except that water produced negative electricity with more certainty. Upon the iron it was sometimes negative, sometimes positive, but mostly none at all; whereas on the bell metal it was almost always negative.

48.-Vinegar produced no electricity when dropped upon the hot bell metal, till water was added to the burnt residuum, which caused a strong positive repulsion.

49.-The bell metal was at last made too hot, and therefore broke to pieces as it was taken out of the fire; I therefore again had recourse to cast iron, and for the sake of its holding fluid substances, I turned a cast metal weight so as to have a very smooth concave surface in the middle, and a concave rim near the edge, so that I could place upon it several substances at once, without mixing. The lean part of a leg of veal was chopped small, and a small quantity placed upon the red-hot cast iron, which caused the gold leaf to open positively, but after burning some time, water was added, which changed its electricity.

50.-The fat of veal was burnt upon the hot iron, which produced no electricity till water was added, which caused a strong negative repulsion both before and after it was burnt black.

51.-Nitre was put upon the hot iron, which melted without producing electricity; then water was dropped upon it, which exploded without producing any electricity; sometimes small globules of water floated a considerable time upon the melted nitre, and then suddenly exploded without ever producing any electrical repulsion or gradual evaporation, as is usual with other substances.

52.-Bees wax produced strong negative electricity, with the addition of water.

53. Verdigrease with water produced very weak positive electricity.

54.-Powdered antimony smoked much, and when water was added the gold leaf opened negatively.

55.-Carraway seeds dropped upon the hot iron caused a strong negative repulsion without the addition of water, also water added