gam rapidly increased to six or seven times its volume, and the compound seemed to contain much more ammoniacal basis than that procured by electrical powers.

The amalgam from ammonia, when formed at the temperature of 70° or 80°, is a soft solid, of the consistence of butter; at the freezing temperature it becomes firmer and a crystallized mass, and its specific gravity is below three. When exposed to air, it soon becomes covered with a white crust, which proves to be carbonate of ammonia.

"The more," says Mr. Davy," the properties of the amalgam obtained from ammonia are considered, the more extraordinary do they appear. Mercury, by combination with about the one twelve thousandth part of its weight of new matter, is rendered solid, yet it has the specific gravity diminished from 13.5 to less than 3, and it retains all its metallic characters; its colour, lustre, opacity, and conducting powers, remaining unimpaired. It is scarcely possible to conceive, that a substance which forms with mercury so perfect an amalgam, should not be metallic in its own nature; hence it may be denominated ammonium."

From the preceding facts, the following questions have occurred: On what do the metallic properties of ammonium depend? Are hydrogen and nitrogen both metals in the aeriform state, at the usual temperature of the atmosphere, bodies of the same character as zinc and quicksilver would be in the heat of ignition? Or are these gases, in their common form, oxides, which become metallized by deoxydation? Or are they simple bodies, not metallic in their own nature, but capable of composing a metal in their deoxygenated, and an alkali in their oxygenated state?

Assuming the existence of hydrogen in the amalgam of ammonium, its presence in one metallic compound evidently leads to the suspicion of its combination in others. And in the electrical powers of the different species of matter, there are circumstances which extend the idea to combustible substances in

general. Oxygen is the only body which can be supposed elementary, attracted by the positive surface in the electrical circuit; and all compound bodies, the nature of which is known, that are attracted by this surface, contain a considerable proportion of oxygen. Hydrogen is the only matter attracted by the negative surface, which can be considered as acting the opposite part to oxygen; "may not then," says the Professor, "the different inflammable bodies, supposed to be simple, contain this as a common element?"

Should future experiments prove the truth of this hypothesis, still the alkalies, the earths, and the metallic oxides will belong to the same class of bodies. From platina to potassium, there is a regular order of gradation as to their physical and chemical properties, and this would probably extend to ammonium, could it be obtained in the fixed form. Platina and gold, in specific gravity, degree of oxydability, and other qualities, differ more from arsenic, iron, and tin, than these last do from barium and strontium. The phenomena of combustion of all oxidable metals, are precisely analogous. In the same manner as arsenic forms an acid, by burning in air, potassium forms an alkali, and calcium an earth; in a manner similar to that in which osmium forms a volatile and acrid substance by the absorption of oxygen, does the amalgam of ammonium produce the volatile alkali; and if we suppose that ammonia is metallized, by being combined with hydrogen, and freed from water, the same reasoning will apply to the other metals, with this difference, that the adherence of their phlogiston, or hydrogen, would be exactly in the inverse ratio of their attraction for oxygen. In platina, it would be combined with the greatest energy; in ammonium with the least; and if it be separable from any of the metals, without the aid of a new combination, we may expect that this result will be afforded by the most volatile and oxidable, such as arsenic, or the metals of the fixed alkalies, submitted to intense heat, under electrical polarities, and having the pressure of the atmosphere removed.

Mr. Davy concludes by hoping, that the new facts which he has discovered may admit of many applications, and explain some phenomena in nature. "The metals of the earths,” he says, "cannot exist at the surface of the globe; but it is very possible that they may form a part of the interior; and such an assumption would offer a theory for the phenomena of volcanoes, the formation of lavas, and the excitement and effects of subterraneous heat; for let it be granted that the metals of the earths and alkalies, in alloy with common metals, exist in large quantities beneath the surface, then their accidental exposure to the action of air and water must produce the effect of subterranean fire, and a product of earthy and stony matter analogous to lavas. The luminous appearance of those meteors, connected with the fall of stones, is one of the extraordinary circumstances of these wonderful phenomena. This effect may be accounted for, by supposing that the substances which fall come into our atmosphere in a metallic state; and that the earths, of which they principally consist, are results of combustion."

At the meeting of the Royal Society, February 2, a most curious and interesting paper, by Mr. Davy, was read, giving an account of various experiments on the action of potassium on ammonia; from which it appears that a considerable quantity of nitrogen can be made to disappear, and can be regenerated. When it disappears nothing can be obtained in its place but oxygen and hydrogen; and when it is formed, its elementary matter is furnished by water.

Messrs. Allen and Pepys have laid before the Royal Society an account of a great number of experiments, made with a view of ascertaining the changes produced in atmospheric air and oxygen gas by respiration; from which they infer,

1. That the quantity of carbonic acid gas èmitted is exactly equal, bulk for bulk, to the oxygen consumed; and therefore there is no reason to conjecture, that any water is formed by a union of oxygen and hydrogen in the lungs.

2. Atmospheric air once entering the lungs returns charged with from 8 to 8 per cent. carbonic acid gas, and when the contacts are repeated almost as frequently as possible, only 10 per cent. is emitted.

3. It appears, that a middle-sized man, aged thirty-eight years, and whose pulse is seventy on an average, gives off 302 cubical inches of carbonic acid gas from his lungs in eleven minutes; and supposing the production uniform for twentyfour hours, the total quantity in that period would be 39,534 cubical inches, weighing 18,683 grains, the carbon in which is 5,363 grains, or rather more than eleven oz. troy: the oxygen consumed in the same time will be equal in volume to the carbonic acid gas. The quantity of carbonic acid gas, emitted in a given time, must depend much on the circumstances under which respiration is performed.

4. When respiration is attended with distressing circumstances, there is reason to conclude, that a portion of oxygen is absorbed and as the oxygen decreases in quantity, perception gradually ceases, and we may suppose, that life would be completely extinguished on the total abstraction of oxygen.

5. A larger proportion of carbonic acid gas is formed by the human subject from oxygen than from atmospheric air.

6. An easy, natural inspiration is from 16 to 17 cubical inches, though this will differ in different subjects; and it is supposed, that the quantity of carbonic acid gas, given off in a perfectly natural respiration, ought to be reckoned at less than at a time when experiments are making on the human subject for the purpose, because in short inspirations the quantity of air, which has reached no farther than the fauces, trachea, &c. bears a much larger proportion to the whole mass required, than when the inspirations are deep.

7. No hydrogen, nor any other gas, appears to be evolved during the process of respiration.

8. The general average of the deficiency in the total amount of common air inspired, appears to be very small, amounting only to 6 parts in 1000.

9. The experiments upon oxygen gas prove, that the quantity of air remaining in the lungs and its appendages, is very considerable; and that without a reference to this circumstance, all experiments upon small quantities of gas are liable to inaccuracy.

Mr. Brande has laid before the Royal Society an account of the differences in the structure of calculi, which arise from their being formed in different parts of the urinary passages; and on the effects that are produced upon them by the internal use of solvent medicines. The experiments made by this gentleman were very numerous, and on an uncommonly large collection of calculi, to most of which histories of the case are annexed. The subject is divided into different sections: the first relates to calculi formed in the kidneys, and voided without having undergone any changes in the urinary passages. These are entirely soluble in a solution of pure potash: and when exposed to the action of the blow-pipe, they blacken and emit a strong odour, which arises from the animal matter which they contain, and which occasions the loss in the analysis of these calculi. Its relative quantity is liable to much variation. In one instance a calculus from the kidney, weighing seven grains, was ascertained to consist of Grains.

In some cases the calculi from the kidneys consist almost wholly of uric acid; sometimes phosphate of lime was combined with the acid.

I. In treating of the calculi which have been formed in the kidneys, and which frequently increase in that situation to a considerable size, he observes, that this augmentation is of two kinds :

1. When there is a great disposition to the formation of uric acid, the calculus consists wholly of that substance and animal