on respiration. Nitrate of ammoniac perfectly neutralised, and rendered as dry at possible, must be exposed to a heat not below 310, or above 400° of Fahrenheit.* At this temperature it is decompounded into water and gaseous oxide of azote, or as I would rather call it nitrous oxide,

The gas must be passed through water, and suffered to remain in contact with it at least an hour and a half before it is respired. A sufficient test of its purity is the combustion of sulphur in it, with a vivid rose coloured flame. The same water should be used for receiving it through, and retaining it in different experiments. A pound of dry nitrate of ammoniac properly decomposed, produces rather more than four cubic feet of air. I have found that the nitrous oxide may be likewise procured in a state of great purity, by exposing nitrous gas to dry sulphate of potash. 1 of nitrous gas decomposed in this manner, produces nearly 05 of nitrous oxide.

The solution of metals in dilute nitrous acid never produces air sufficiently pure for respiration, and the decomposition of nitrous gas by the sulphures, wetted iron, &c. is a process too slow ever to be employed with advantage.

My investigation of the nature, properties, &c. of the nitrous oxide and the ærieform fluids relating to it, will consist,

1. Of experiments on its production, from the decomposition of nitrous acid and nitrous gas in different modes, its analysis, and the analysis of the substances connected with it.

2. On its action on different incombustible substances, on the combustion of charcoal, sulphur, iron, phosphorus, and hydrogen in it, on its decomposition by the compound combustible bodies, &c. 3. On its absorbtion in respiration, with a general investigation of this process, and the changes effected in different gases by it.

4. A history of its effects, containing the experience of different individuals who have respired it, furnished by themselves. Every day we gain new evidences in favour of its powers. A number of persons have breathed it since the publication of Dr. Beddoes's notice; all have been affected, and by far the greater number pleasantly. As yet we have tried it in no disease, except palsy; but as it supplies to the system two principles so essential to perceptive existence, as oxygen and nitrogen, and increases the powers of life generally without producing any ascertainable exhaustion; there is reason to hope that it will be a powerful agent in many diseases of debility.

An experiment on the collision of flint and steel in vacuo, and in carbonic acid, published in my Essay on Heat and Light,+ differs considerably in its results from a similar one made long ago by the

This decomposition was discovered by the illustrious Berthollet. I have found that at a temperature above 500°, nitrous gas and nitrogene are evolved as well as nitrous oxide. Whenever there is a luminous appearance in the retort, more or less of these two substances will be produced.

+ West Country Contributions.

*

ingenious Mr. Hawksbec. In repeating my experiment a number of times under new circumstances, I have discovered the cause of this difference; when the gunlock is snapped in carbonic acid, or in water, if a sharp and thin flint be made use of, and the springs be strong, a faint red light is generally perceptible; but if the flint be thick, and sufficiently sharp only to strike off particles from the steel, without suffering considerable abrasion of its own parts; though vivid sparks are produced in the atmosphere, not the slightest luminous appearance is perceptible in carbonic acid. If instead of flint, fluor spar, phosphate of lime, or sugar, be rubbed pretty briskly against steel in carbonic acid, as much light is produced as when they are rubbed against it in common air. These facts induce me to believe, that whenever light is produced by the collision of flint and steel in carbonic acid, it arrises from the collision of small particles of flint against each other, and never from the ignition of steel. I have often examined in a microscope, the small particles of steel struck off by flint in carbonic acid; the edges are generally deprived of metallic lustre, and exhibit an appearance of fusion; it is probable, however, that this appearance is owing to a partial oxidation of the particle, from the decomposition of the water held in solution by carbonic acid. In Mr. Hawksbee's experiments, the apparatus was contrived in such a way, as to produce perpetual abrasion of particles of flint. In my experiment the flint was not sufficiently thin to produce light in carbonic acid, consequently it ought to have produced none in vacuo; but if (as the facts I am about to detail render probable) the light produced by flint, fluor spar, phosphate of lime, &c. on collision be electrical, there are strong reasons for believing, that in a Torricellian vacuum, or in a vacuum formed by the absorbtion of carbonic acid, by a solution of potash sufficiently concentrated to form a solid compound with it, no light would be visible.

Mr. T. Wedgwood found, that fluor spar, phosphate of lime, flint, &c. were luminous, not only when heated, but when struck together, and that under water, or in any kind of air. Scheele discovered that fluor spar, after calcination, lost its phosphorescence. I exposed to a long continued red heat fluor spar, phosphate of lime, sulphate of strontian, sulphate of barytes, glass, sulphate of lime, and carbonate of lime, all of which were before phosphorescent, and produced light by collision under water.

After being suffered to cool in the light, they were placed on a heated iron successively. The fluor spar, the phosphate of lime, and the sulphate of strontian and barytes, were not phosphoric at any temperature. The calcarious spar, which had lost a portion of its carbonic acid, and the gypsum, were nearly as luminous as before; the phosphorescence of the glass and flint was barely perceptible.

Two pieces of the calcined fluor were now rubbed together, they

Phil. Trans. No. XXIV. 2185. (or Hawksbee's Physicomechan, Exper. 2d. edit. octavo, London, 1719, page 26.)

produced as much light as before. The phosphate of lime, the calcareous spar, and the gypsum, had lost their coherence; so that the pieces could not be rubbed against cach other with sufficient force. The sulphate of strontian and barytes, the glass, and the silex, produced as much light as before on collision.

I found that all these bodies were non-conductors of electric fluid. On rubbing a large crystal of quartz with woollen it became highly electric. Fluor spar was likewise made electric when heated and strongly rubbed. To prove, however, more satisfactorily, whether the light produced by the collision of two non-conductors was electric, two cylinders of glass were struck against each other, so as to produce light, and one of them was placed in contact with a Leyden phial. After a number of collisions, on applying a conductor to the phial, I procured a small spark.

Two pieces of pyrites, sufficiently hard to cut glass, and extremely brittle, produced an immense quantity of light, when struck together, in the atmosphere; but not the slightest luminous appearance under water. This body is a good conductor of electric fluid. Do not these facts go far to prove that light, when produced by the collision of bodies in water or non-respirable air, is electric; and generated by the rapid transmission of electrical fluid, excited by collision between two non-conducting surfaces, to a conducting body? And as iron can be heated, to a degree at which it is capable of decomposing oxygen gas, in a non-respirable air without being luminous; and as pyrites is not luminous under water, is it not probable that light is accidental to, and not necessarily produced by, high temperature? The admission of such inferences would be favourable to my theory of the combinations of light; but facts have occurred to me with regard to the decomposition of bodies which I have supposed to contain light, without any luminous appearance. Till I have satisfactorily explained these facts by new experiments, I beg to be considered as a sceptic with regard to my own particular theory of the combinations of light and theories of light in general. On account of this scepticism, and for other reasons, I shall in future use the common nomenclature; excepting that as my discoveries concerning the gaseous oxide would render it highly improper to call a principle which in one of its combinations, is capable of being absorbed by the venous blood, and of increasing the powers of life, azote, I shall name it, with Dr. Pearson, Mr. Chaptal, &c. nitrogene, and the gaseous oxide of azote, the properties and composition of which have been misunderstood by the chemists who gave it that name, nitrous oxide.

a

Many months ago I made a number of experiments on the composition, analysis, and decomposition of the ammoniacal salts. These experiments have afforded me curious and interesting results; but wish to complete the investigation relating to the nitrous oxide have prevented me from pursuing them to their full extent. Among these results, as affording useful, practical applications, I shall mention the decomposition of the carbonate and sulphate of ammonia. Car

bonate of ammonia undergoes a change it its composition with every change of its temperature; on being heated it gives out carbonic acid, and when cooled absorbs it again; when passed through a tube, heated red, it is decompounded into water, charcoal, nitrogen, and hydro-carbonate. Sulphate of ammonia, the partial decompositon of which was discovered by Mr. Hatchet, when sent through a tube heated red, is decompounded into sulphur, water, and nitrogen. I remain, sir,

Feb., 1800.

Yours, with much respect,

H. DAVY.

An Account of some Experiments made with the Galvanic Apparatus of SIGNOR VOLTA. By Mr. DAVY, Superintendent of the Pneumatic Institution.

In pursuing a course of experiments on the galvanic influence, I have made some new observations. They are connected with the curious facts already detailed in Mr. Nicholson's "Philosophical Journal," and they may possibly lead to elucidations of the pheno

mena.

The apparatus that I employed was constructed for Dr. Beddoes, and never consisted of less than 110 pairs of metallic plates. I found the sensible galvanic shock very much increased, when the parts communicating with the conductors were moistened with solution of green sulphate of iron. A pile erected with pieces of cloth, wetted in that substance, acted rather more intensely than a similar pile erected in the usual mode. It, however, lost its powers in a shorter time: perhaps a solution of sulphate of zinc may be employed with advantage.

a. Struck with the curious phenomena noticed by Messrs. Nicholson and Carlisle, namely, the apparent separate production of oxygen and hydrogen from different wires, or from different parts of the water completing the galvanic circle, my first researches were directed towards ascertaining if oxygen and hydrogen could be separately produced from quantities of water not immediately in contact with each other.

Two silver wires, one from the zinc end of the apparatus, and the other from the silver end, were made to communicate with the two glasses, distant from each other about five inches, and filled with water that had been long boiled, and was yet warm. Into one of these glasses I dipped the fingers of my right hand, and into the other the fingers of my left, so that the communication between them was made through my body. Immediately after the shock, the zinc wire began to calcine very fast, white clouds diffusing * To prevent unnecessary repititions, after Mr. Cruickshank, I have called the wire connected with the zinc end of the apparatus, the zinc wire, and that connected with the silver end, the silver wire.

themselves from it through the water. At the same time gas was formed round, and extricated from the silver wire in the other glass. The communication was kept up for half an hour; during this time no gas was produced from the zine wire, which continued to calcine throughout the process. The gas from the silver wire was caught in a small inverted cylinder; examined by the test of nitrous gas, it appeared to contain no oxygen, and inflamed with twice its bulk of common air, gave such a diminution, as denoted it to be hydrogen nearly pure.

This apparatus being adjusted as before, the communication between the glasses was made through three persons; the process went on, though less rapidly; the oxygen was fixed as before by the silver in one vessel, whilst the hydrogen was given out in the other. When muscular fibre, living vegetable fibre, or a moistened thread not exceeding three feet in length, was employed as the medium of connection between the glasses, similar effects were produced, though the gas was evolved more slowly than when the living animal was the connector. Muscular fibre appeared to be a better conductor than vegetable fibre, and yegetable fibre a better conductor than the moistened thread.

b. Several glass tubes about one-third of an inch in diameter, and four inches long, having each a piece of gold wire inserted into one end hermetically sealed, and the other end open, were provided. Two of these tubes were filled with distilled water, and inserted into separate glasses filled with that fluid. The glasses were made to communicate by means of fresh muscular fibre; the gold wires were connected with the machine by means of silver wires; one with the silver end, the other with the zinc end. Gas was immediately given out from both the gold wires; but most rapidly from that connected with the silver. In four hours and a quarter the process finished; the water in the tube communicating with the silver being below the gold wire. The gases were examined; the quantity from the water communicating with the zinc was equal to thirty-three grain measures; that from the water connected with the silver, to nearly sixty-five grain measures. The zinc gas was mingled with eighty measures of nitrous gas, containing nitrogen; a rapid diminution took place, and when the residuum was exposed to solution of green muriate of iron,* not quite five measures remained. Hence the thirty-three measures of gas evidently contained more than thirty-one measures of oxygen. The sixty-one measures in the other tube, gave with nitrous gas a diminution but barely perceptible, and fired after the absorption of the nitrous gas by the electric spark, with sixty measures of oxygen, left a residuum nearly equal to thirty-six measures; hence the gas was hydrogen almost pure.

• Solution of green muriate of iron rapidly absorbs nitrous gas, without effecting any change in it at common temperatures, and it is possessed of no action on gases not absorbable by water, and incapable of supporting flame. Solution of green sulphate of iron likewise absorbs nitrous gas without decomposing it.