The nitrous oxide, as fast as it is formed by the action of the sulphite on the nitrous gas, is absorbed by the free alkali; and thus a permanent union is effected between the two bodies.

C. The compound of nitrous oxide and potash is very soluble in water, but apparently insoluble in alcohol. Its taste is not very different from that of caustic potash, perhaps a little more pungent. When acted upon by the acids it gives out nitrous oxide. This gas is likewise disengaged from it in a pure form by the application of a heat above 400°, Fahrenheit. It produces scintillations when thrown upon red hot charcoal.

d. The properties of the combination of soda and nitrous oxide are not materially different from those of the compound of potash and nitrous oxide.

IV. Of the Action of Heat and Electricity on Nitrous Oxide. Sect. 1. Nitrous oxide undergoes no change in its composition at temperatures below those of ignition, though exposed to them for ever so great a length of time. When, however, it is passed through a porcelain tube, heated red, or when it is acted on for a long while by the electric spark, a new arrangement of its principles takes place and it becomes converted into nitrous acid, and a gas analogous to atmospheric air, but containing a little less oxygen.*

The nitrous acid formed in this process is very small in quantity, but the unabsorbable gas equals about ,8 of the original volume of the nitrous oxide.

V.-On the Decomposition of Nitrous Oxide by Combustible Bodies.

Sect. 1. The changes produced in nitrous oxide by heat, are probably intimately connected with the phenomena of its decomposition by the inflammable bodies, which in general require, for their combustion in this gas, much higher temperatures than those at which they burn in atmospheric air or oxygen. When they are intensely heated, they act upon it, and become oxygenated, nitrogen being evolved, and much heat and light generated.

During the combustion of solid and fluid bodies producing flame in nitrous oxide, nitrous acid is formed, most likely in consequence of a new arrangement of principles produced by the ignition of a part of the gas not in contact with the burning substance. Likewise when nitrous oxide in excess is decomposed by inflammable gases, nitrous acid, nitrogen, and a little oxygen, are produced, probably from the same cause.

a. Pyrophorus, which inflames in nitrous gas and in atmospherio air, at or even below 40°, Fahrenheit, requires for its combustion in nitrous oxide a temperature nearly equal to that of ignition.

Dr. Priestley first observed, that nitrous oxide, after being acted upon by the electric spark, became immiscible with water; but he did not notice the nitrous acid produced in the process; neither did the Dutch chemists, who repeated his experiments.

b. Phosphorus may be fused and even sublimed in nitrous oxide without effecting any change in it; but when it is introduced into it in a state of active inflamation, it burns with intensely vivid light.

c. Sulphur does not act in nitrous oxide when introduced into it, burning with the feeble blue flame; but if in a state of vivid inflamation, it decomposes it with the production of a beautiful rose-coloured light.

d. Iron and charcoal, when heated white, burn in nitrous oxide with much greater vividness than in the atmosphere.

e.

The lighted taper, introduced into nitrous oxide, burns at first as in oxygen; but afterwards with a flame, white in the centre, and blue at the circumference; a phenomenon apparently depending upon the nitrous acid formed in the process.

f. Hydrogen, and the compound inflammable gases, when mingled in certain proportions with nitrous oxide, and acted on by the electric spark, explode, with the production of much light and heat.*

Sect. 2. When nitious acid is formed in processes of combustion in nitrous oxide, so at to remain in the residual gas, the quantity of free nitrogen evolved never equals more than of the volume of the nitrous oxide decomposed, though when this substance is not produced, 10 of nitrous oxide give out about 11 of nitrogen.

Sect. 3. The heat produced by even the slow combustion of bodies in nitrous oxide, is in all cases sufficient to keep up the process for a certain time, after the original heating cause is removed; but in proportion as the volume of nitrogen increases, the inflammation diminishes in vividness, and it uniformly ceases before the whole of the gas is decomposed. Charcoal and iron cease to burn in nitrous oxide when it is mingled with an equal volume of nitrogen; yet the combustion of phosphorus will continue (though feebly) in a gas consisting of 4 nitrogen and 1 nitrous oxide.

VI.—On the Analysis of Nitrous Oxide.

Sect. 1. a. One hundred cubic inches of nitrous oxide weigh at temperature 55°, Fahrenheit, and atmospheric pressure 30 about 50-2 grains.

b. Four cubic inches of this gas, when perfectly decomposed by the combustion of charcoal, are converted into about 2.2 cubic inches of carbonic acid, and 4.2 cubic inches of nitrogen; no nitrous acid being produced in the process.

C. Likewise 2 cubic inches of nitrous oxide require, for their complete decomposition, about 2.2 cubic inches of hydrogen, and evolve during the inflammation, a quantity of nitrogen, nearly equal to it in volume.

The Society of Chemists at Amsterdam thought that hydrogen was the only body capable of decomposing nitrous oxide. From their experiments it appears probable that in many cases they did not raise the temperatures of other inflammable bodies sufficienty high for this purpose.

D d

b. Comparing these facts with other facts relating to the production of nitrous oxide, we may conclude that 100 parts of this gas are composed of about thirty-seven parts oxygen and sixty-three parts nitrogen, existing in a much more condensed state than when in their simple forms.

c. The oxygen appears to be combined with the nitrogen much more intimately in nitrous oxide than in nitrous gas; a phenomenon that may be easily accounted for, when we consider the general law of saturation.+

VII. On the Action of Nitrous Oxide on Living Beings.

Sect. 1. Nitrous oxide when taken into the mouth tastes faintly sweetish. Its odour is weak, but agreeable. It is respirable, and produces very peculiar effects, when made to act on the system by means of the lungs.

The sensations it occasions are in general analogous to those connected with intoxication from fermented liquors.

a. Healthy persons after breathing it accurately for a minute and a half, or two minutes, are usually exhilarated, and affected by strong pleasurable sensations, the circulation is quickened, the countenance becomes darker, and a sense of warmth is induced.

b. On unhealthy persons the effects are less pleasant, and in certain cases it has induced hysterical affections.

c. Nitrous oxide after being breathed for more than three minutes, produces violent excitement, which generally ends in momentary loss of sensation.

d. As far as experiments have yet gone, there is no reason to believe that any notable debility follows, even its most violent agency.

Sect. 2. Warm blooded animals, when permanently immersed in nitrous oxide, live longer in it than any other gases, except such as contain free oxygen; but cold blooded animals are quickly destroyed by it.

a. The smaller quadrupeds die in pure nitrous oxide in three or four minutes; they absorb a little of the gas, and their death seems to be occasioned by excessive stimulation.

b. When examinated after death their internal parts are found to have undergone peculiar changes.

The animal fibre is very inirritable; the blood both in the arteries and veins is dark and purple, and the lungs are marked with large purple spots.

Sect. 3. When nitrous oxide is exposed to fluid venous blood, whether in the vessels or out of them, it is rapidly absorbed, apparently no portion of it is decomposed, and the colour of the blood becomes rather more inclined to purple.

• This estimation is very analogous to that of the Dutch chemists. The affinity of one body for another is inversely as its saturation with it.

An Account of some Galvanic Combinations, formed by the arrangement of single Metallic Plates and Fluids, analogous to the new Galvanic Apparatus by Mr. Volta. By MR. HUMPHRY DAVY, Lecturer on Chemistry in the Royal Institution.

I. ALL the galvanic combinations analogous to the new apparatus of Mr. Volta, which have been heretofore described by experimentalists, consist (as far as my knowledge extends) of series containing at least two metallic substances, or one metal and charcoal, and a stratum of fluid. And it has been generallly supposed, that their agencies are, in some measures, connected with the different powers of the metals to conduct electricity. But I have found that an accumulation of galvanic influence, exactly similar to the accumulation in the common pile, may be produced by the arrangement of single metallic plates, or arcs, with different strata of fluids.

The train of reasoning which led to the discovery of this fact, was produced by the observation of some phenomena relating to the connection of chemical changes with the evolution of galvanic power.

It appeared, in several experiments, that series of double metallic plates, incapable of acting as galvanic combinations, when arranged in the proper order, with portions of water, were readily made to produce galvanic effects, by being alternated with acids, or other fluids capable of oxidating one only of the metals of the series. Thus, double plates, composed of silver and gold, (metals which have been supposed to differ very little in their powers of conducting electricity,) produced galvanic action, when placed in contact, in the common order, with cloths moistened in diluted nitric acid. copper and silver acted powerfully with nitrate of mercury.

And

These facts induced me to suppose, that the alteration of two metallic bodies with fluids, was essential to the production of accumulated galvanic influence, only so far as it furnished two conducting surfaces of different degrees of oxidability; and that this production would take place, if single metallic plates could be connected together by different fluids, in such a manner that one of their surfaces only should undergo oxidation, the arrangement being regular.

On this supposition, I made a number of experiments on different arrangements of single metals and fluids; and, after many various processes, I was enabled to ascertain, that many of these arrangements could be made active, not only when oxidations, but likewise when other chemical changes were going on in some of their parts.

In describing the different galvanic combinations formed by single metallic plates and fluids, I shall divide them into three classes, following, in the arrangement, the order of time with regard to dis

covery.

II. The first and most feeble class is composed, whenever single metallic plates, or arcs, are arranged in such a manner that two of their surfaces, or ends opposite to each other, are in contact with

different fluids, one capable, and the other incapable, of oxidating the metal. In this case, if the series are numerous, and in regular alternation, galvanic influence will be accumulated, analogous, in all its effects, to the influence of the common pile.

Tin, zinc, and some other easily oxidable metals act most powerfully in this class of combinations.

If pieces of polished tin, about an inch square, and one-twentieth of an inch thick, be connected with woollen cloths of the same size, (moistened, some in water, and some in diluted nitrous acid,) in the following order, tin, acid, water, and so on, till twenty series are put together, a feeble galvanic battery will be formed, capable of acting weakly on the organs of sense, and of slowly producing the common appearances in water; the wire from the oxidating surface of the plates evolving hydrogen; and the wire from the non-oxidating surface (when of silver) depositing oxide.

In all cases, when the batteries of the first class are erected perpendicularly, the cloth moistened in acid must be placed under the cloth moistened in water; and, in this arrangement, as the acid is specifically heavier than water, little or no mixture of the fluids will take place.

When zinc is employed, on account of its rapid oxidation in water containing atmospheric air, three cloths should be used; the first moistened in weak solution of sulphuret of potash, (which is possessed of no power of action upon zinc, and which prevents it from acting upon the water;) the second moistened in a solution of sulphate of potash, of greater specific gravity than the solution of sulphuret: and the third wetted in an oxidating fluid specifically heavier than either of the solutions. In this case, if the order be as follows, zinc, oxidating solution, solution of sulphate of potash, solution of sulphuret of potash, very little mixture of the fluids, or chemical action between them, will take place: and an alternation of twelve series of this kind, forms a battery capable of producing sensible effects.

III. The second class of galvanic combinations with single plates is formed, when plates, or arcs, composed of a metallic substance capable of acting upon sulphurated hydrogen, or upon sulphurets dissolved in water, are formed into series, with portions of a solution of sulphuret of potash, and water, in such a manner that one side of every plate, or arc, is in contact with water, whilst the opposite side is acted on by the solution of sulphuret. Under these circumstances, when the alternation is regular, and the number of series sufficiently great, galvanic power is evolved; and water, placed in the circuit with silver wires, is acted on; oxide being deposited on the wire connected with the side of the plate undergoing chemical alteration, whilst hydrogen is evolved from the side in contact with water.

Silver, copper, and lead, are each capable of forming this combination. Plates made from either of those metals, may be arranged with cloths, (moistened, some in water, and others in solution of sulphuret of potash), in the following order, metal, cloth moistened in sulphuret of potash, cloth moistened in water, and so on.