General illustrations and

us to hope, that the new mode of analysis may lead us to the applications discovery of the true elements of bodies, if the materials acted on be employed in a certain state of concentration, and, the electricity be sufficiently exalted. For if chemical union be of the nature which I have ventured to suppose, however strong the natural electrical energies of the elements of bodies may be, yet there is every probability of a limit to their strength; whereas the powers of our artificial instruments seem capable of indefinite increase.

Alterations of electrical equilibrium are continually taking place in nature; and it is probable that this influence, in its faculties of decomposition and transference, considerably interferes with the chemical alterations occurring in different parts of our system.

The electrical appearances which precede earthquakes and volcanic eruptions, and which have been described by the greater number of observers of these awful events, admit of very easy explanation on the principles that have been stated.

Beside the cases of sudden and violent change, there must be constant and tranquil alterations, in which electricity is concerned, produced in various parts of the interior strata of our globe.

Where pyritous strata and strata of coal-blende occur, where the pure metals or the sulphurets are found in contact with each other, or any conducting substances, and where different strata contain different saline menstrua, electricity must be continually manifested; and it is very probable, that many mineral formations have been materially influenced, or even occasioned by its agencies.

In an experiment that I made of electrifying a mixed solution of muriates of iron, of copper, of tin, and of cobalt, in a positive vessel, distilled water being in a negative vessel, all the four oxides passed along the asbestus, and into the nega tive tube, and a yellow metallic crust formed on the wire, and the oxides arranged themselves in a mixed state round the base of it.

In another experiment, in which carbonate of copper was diffused through water in a state of minute division, and a negative wire placed in a small perforated cube of zeolite in

the

the water, green crystals collected round the cube; the partis General illuscles not being capable of penetrating it.

By a multiplication of such instances the electrical power of transference may be easily conceived to apply to the explanation of some of the principal and most mysterious facts in geology.

And by imagining a scale of feeble powers, it would be easy to account for the association of the insoluble metallic and earthy compounds containing acids.

Natural electricity has hitherto been little investigated, except in the case of its evident and powerful concentration in the atmosphere.

Its slow and silent operations in every part of the surface will probably be found more immediately and importantly connected with the order and economy of nature; and inves tigations on this subject can hardly fail to enlighten our philosophical systems of the Earth; and may possibly place new powers within our reach.

Explanation of the Figures.

Pl. I. Fig. 1, Represents the agate cups, mentioned Vol. XVIII, p. 323.

Fig. 2, Represents the gold cones, page 325,

Fig. 3, Represents the glass tubes, and their attached apparatus, page 337.

Fig. 4, Represents the two glass tubes, with the intermediate vessel, page 338.

In all the figures A B denote the wires, rendered one positively, the other negatively electrical; and C the connecting pieces of moistened amianthus.

XIII.

Memoir on the Analysis of the Sweat, the Acid it contains, and the Acids of the Urine and Milk; read to the National Inftitute by Mr. THENARD*.

IF

trations and applications.

F we examine the principal fluids of the animal economy, Animal fluids we find, that some are alkaline, and the others acid. To the acid or alka.

2

line.

Annales de Chimie, vol. LIX, p. 262, Sept. 1806.

alkali.

first class belong the blood and bile: to the second, the urine, milk, and sweat.

Hence arise naturally two questions; what are the alkalis, and what are the acids, proper to these fluids? The first has Soda the only already been solved, as the researches of Cadet and Deyeux have proved, that we never meet with any alkali but soda in What are the animal substances. The solution of the second however is acids. but little advanced: even the data, that might lead to it, are for the most part inaccurate: and many of the results relating to some of these parts are too deficient in proof, to be placed in the rank of demonstrated truths. This is the question therefore, that will form the subject of the present memoir; and, that I may treat it in a manner suitable to the object I have in view, I shall first present as fuil an analysis of the sweat, as we have of urine and of milk.

Sweat.

That of an adult from

PART I. Of the Sweat.

The sweat is a fluid separated from the blood in the skin by exhalant vessels, with which its texture is traversed or filled. It is more or less copious in different individuals: and its quantity is perceptibly in the inverse ratio of that of the urine. All other circumstances being similar, much more is produced during digestion than during repose. The maximum of its production appears to be twenty-six grains 1320 grs. near 2 lbs. avoird., and two thirds in a minute, the minimum nine grains, troy to 38400, near weight. It is much inferior however to the pulmonary tran5 lbs. per day. spiration: and there is likewise a great dillerence between their nature and mauner of formation. The one is the product of a particular secretion, similar in some sort to that of the urine: the other, composed of a great deal of water and carbonic acid, is the product of a combustion gradually effected by the atmospheric air.

That from the
Jungs still

more.

The first a secretion.

Its qualities.

The sweat, in a healthy state, very sensibly reddens litmus, paper or infusion. In certain diseases, and particularly in putrid fevers, it is alkaline: yet its taste is always rather saline, and similar to that of salt, than acid. Though colourless, it stains linen. Its smell is peculiar, and insupportable when it is concentrated, which is the case in particular during distillation. But before I speak of the trials to which I subjected it, and for which I had occasion for a great quantity,