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as he thinks that accident is to be attributed solely to this circumstance. The fact of the high level of the channel during strong winds between W. and S. W. appears to rest on the most satisfactory proof; and, as the form of the channel does not permit the ready escape of the water, a current must be produced, in the straits of Dover, capable of disturbing considerably the reckoning of ships navigating there at these periods. The direction of the current must depend, of course, on the form and position of the opposite shores, and from the direction of these Major R. infers, that on the English side it will set to the north east; but, as the coast of Boulogne presents a direct obstacle to the water, the level of the sea there will be higher than on the opposite shore, and the current consequently stronger towards the Goodwin. From these considerations, Major R: concludes, that a ship passing the strait of Dover, at the back of the Goodwin sands, during the prevalence of W. or S. W. winds, will be carried many miles northward of her reckoning; and, if compelled to depend on it, may be subject to great hazard from the Goodwin.' p. 402.

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XXV. On Respiration. By William Allen, Esq. F. R. S. and William Hasledine Pepys, Esq. F. R. S. Read June 22, 1809.

This valuable memoir presents us with the continuance of an investigation, of which a considerable and interesting portion has appeared already in the Transactions of the Society*. In their former experiments, these gentlemen had observed, that when oxygen gas nearly pure was respired, a quantity of azot was evolved greater than could be accounted for satisfactorily by supposing it to have formed part of the air previously existing in the lungs; and the experiments here detailed were made chiefly to clear up the circumstance. In an experiment in which 2668 cubic inches of oxygen gas were employed, the azot after the experiment amounted to 211. 30 cubic inches. The oxygen contained originally only four per cent, or 106. 72 cubic inches, and there was consequently an increase of 105.08 cubic inches, a quantity much too great to be attributed to the air contained in the lungs at the commencement of the operation. To determine the question, however, as fairly as possible, the lungs of a stout man of about five feet ten inches high were procured soon after death; and their capacity determined with every requisite precaution. The quantity of air obtained from them, was 91.134 cubic inches; and correction being made for the temperature of the living body, and other circumstances, the air left in the lungs, after the complete expiration which takes

* Phil. Trans. 1808. Part II, See Ecl. Rev. Vol. V. p. 516,

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place at death, is estimated in this instance at 103 cubic inches. On taking the results, however, of four experiments made with every possible attention to accuracy, and estimating the capacity of the lungs by the quantity of azot evolved, the average would be 183 cubic inches; a difference too great to be reconcilable to any other idea, than that either azot is given out by the blood, or actually formed when pure oxygen is respired. In addition to the evidence derived from these facts, it was determined to perform a series of experiments on some animal living entirely on vegetable food; and a guinea pig was selected for the purpose. experiments were made, in the first instance, with atmospheric air; and in these the proportion of azot remained undisturbed; but, when oxygen gas was used, the azot evolved in one hour and twelve minutes was 50. 12 cubic inches, a quantity more than equal to the solid contents of the body of the animal. A similar experiment, made with a smaller animal, gave similar results. When a mixture of 22 parts of oxygen and 78 of hydrogen was used, azot was found to be evolved in considerable quantity, the increase being 57. 40 cubic inches when 750 cubic inches of the mixed gases were employed, and the time about 45 minutes.

The foregoing experiments seem to prove, 1. That when atmospheric air alone is respired, even by an animal subsisting wholly upon vegetables, no other change takes place in it, than the substitution of a certain portion of carbonic acid gas, for an equal volume of oxygen. 2. That when nearly pure oxygen gas is respired, a portion of it is missing at the end of the experiment, and its place supplied by a corresponding quantity of azote; the portion evolved in a given time, being greater in the early than in the later periods. 3. That the same change takes place when an animal is made to breathe a mixture of hydrogen and oxygen, in which the former is in nearly the same proportion to the latter, as azote to oxygen in atmospheric air. 4. That an animal is capable of breathing a mixture of 78 parts hydrogen and 22 oxygen, for more than an hour, without suffering any apparent inconvenience. 5. That the excitability of an animal is much diminished when he breathes any considerable proportion of hydrogen gas, or that it at least has a tendency to produce sleep. 6. That there is reason to presume an animal evolves less carbonic acid gas during its sleeping, than in its waking hours. 7. That the lungs of a middle sized man contain more than 100 cubic inches of air after death.'

XXVI. Experiments on Ammonia, and an Account of a new Method of analyzing it, by Combustion with Oxygen and other Gases; in a Letter to Humphry Davy, Esq. Sec. R. S from William Henry, M. D., F. R. S. &c. V. P. of the Literary and Philosophical Society, and Physician to the Infirmary at Manchester.

The primary object of these experiments was, to ascertain

if oxygen entered into the composition of ammonia. It was ascertained, by experiments, conducted in the most unexceptionable manner, that no oxygen was produced by the action of electricity upon ammonia, even when the metallic surfaces of the platina wires exposed to the gas were mere points of i of an inch diameter; nor did any water appear to be produced. Some appearance of moisture, indeed, was perceptible after electrization, which was not sensible to the same tests before, even when all possible care was taken to exclude it; but the quantity was so trifling, that Dr. H. concludes it was derived from the mercury, or some extraneous source. The tediousness and difficulty of decomposing ammonia by electricity, led Dr. H. to attempt it by other means; and a mixture of oxygen and ammoniacal gas more than answered his expectations. These gases mixed in proper proportions may be detonated over mercury by electricity, as readily as a mixture of oxygen and hydrogen, and an easy and precise method of analysing ammonia is thus obtained. When the oxygen exceeds the proportion of 3 to 1 of the ammonia, or the ammonia that of 3 to 1. 4 of oxygen, the mixture ceases to be combustible; but when the proportions best adapted to inflammation are used, the oxygen may be diluted with six times its bulk of atmospherical air, without losing its property of burning with ammonia. Atmospheric air alone, however, does not answer the purpose in auy proportion; but when electrified together for a long time, the ammonia is at length decomposed, water being one of the products. The products of the combustion of ammonia with oxygen vary according to the proportions of the two gases. If the oxygen exceed considerably the ammonia (as 2 to 1 or upwards in bulk) the ammonia disappears entirely, and no gases remain except nitrogen, mixed with the superabundant oxygen; but a dense cloud appears immediately on the detonation taking place, which from its characters Dr. H. concludes to be nitrat of ammonia, but the quantity was too minute for analysis. The nitrogen of the residuary gas, was found to be less than ought to result from the ammonia decomposed. When, on the contrary, the ammonia exceeds the oxygen gas considerably, no cloudiness appears, nor is any nitrous acid produced; but it is remarkable, that, even when the oxygen is less than sufficient to saturate the hydrogen, the whole of the ammonia is nevertheless completely reduced, the residuary gas being a mixture of hydrogen and nitrogen, which may be again inflamed by the electric spark on the addition of a second portion of oxygen, and in this way the whole bydrogen of the ammonia may be saturated with

oxygen, and the nitrogen obtained as a final result, affording a most easy and simple mode of decomposition.

The principal experiments detailed in this paper, were made with a deficient proportion of oxygen; and though their results are not perfectly uniform, they are perhaps as nearly so as could be expected in the analysis of a substance having so powerful an affinity for moisture, of which the minutest quantity must affect the results of the decomposition.

The proportions of oxygen and ammonia which most nearly saturate each other, are stated at 674 measures of oxygen to 100 of ammonia, or 100 of the former to 148 of the latter; and the composition of ammonia, as determined by these experiments, agrees very nearly with that assigned by Mr. Davy, (74 hydrogen to 26 azot): but the proportion of the hydrogen was generally rather too low, owing, as Dr. H. suspects, to the imperfection of the mode of analysing a mixture of hydrogen and nitrogon. Dr. H. found that a stream of ammonia burns in oxygen with a pale yellow flame. With nitrous oxide it forms a mixture which is extremely combustible; if the nitrous oxide is in excess, the propor→ tions have a considerable range, but the ammonia must not be less than of the whole; when the ammonia is in excess, combustion does not take place except the oxide forms

of the mixture. Nitrous gas, also, may be employed for the combustion of ammonia, the proportions required for mutual saturation being 120 measures of nitrous gas to 100 of ammonia.

In the conclusion of this interesting memoir, we are presented with some observations on the effect of long conti nued electrization or carburetted hydrogen, olefiant gas, and carbonic oxide, a subject which formerly occupied a considerable share of Dr. Henry's attention. The two former are decomposed by electricity; but on carbonic oxide it produces no change, eleven hundred discharges from a Leyden phial having had no effect upon a quantity equal to about of a cubic inch.

XXVII. New analytical Researches on the Nature of certain Bodies, being an Appendix to the Bakerian Lecture for 1808. By Humphry Davy, Esq. Sec. R. S. Prof. Chem. R. I. 1. Further inquiries on the Action of Potassium on Ammonia and on the analysis of Ammonia. Mr. Davy's preceding researches, (of which an account will be found in our analysis of the first part of this volume of the Society's Transactions, E. R. Vol. V. p. 757.) satisfactorily prove, that when ammonia is

acted upon by potassium, part of the nitrogen of the ammonia disappears, some gas is developed, and a fusible substance of a dark olive colour remains behind. The object of the experiments now detailed, was to determine the nature of the gas developed; and whether the basis of nitrogen was capable of forming an alloy with the metals used in the experiment, or, in other words, whether it was of a metallic nature. The experiments made upon the gas prove it to be pure hydrogen; by slow combustion with oxygen it was converted into water, and its weight corresponded exactly with that of an equal quantity of hydrogen. The results with respect to the metallic nature of the base of nitrogen, though not conclusive, are for the most part negative. The potassium reproduced in the distillation of the fusible substance exhibits precisely the usual properties, and presents the same results by combustion in oxygen, and by the action of water. The surface of the iron on which it had been distilled, though corroded and rendered brittle, gave hydrogen alone when dissolved in muriatic acid; and, when the gas evolved during the distillation in an iron vessel was made to pass through mercury, the mercury remained unaltered in its appearance, and did not effervesce when thrown into water.

That the nitrogene which disappears in this experiment is absolutely converted into oxygene and hydrogene, and that its elements are capable of being furnished from water, is a conclusion of such importance, and so unsupported by the general order of chemical facts, that it ought not to be admitted, except upon the most rigid and evident experimental proofs. I have repeated the experiment of the absorption of ammonia by potassium in trays of platina or iron, and its distillation in tubes of iron more than twenty times, and often in the presence of some of the most distinguished chemists in this country, from whose acuteness of observation, I hoped no source of error could escape. The results, though not perfectly uniform, have all been of the same kind as those described in page 55 (Bak. Lect.) Six grains of potassium, the quantity constantly used, always caused the disappearance of from 10 to 12. 5 cubical inches of well dried ammonia. From 5.5 to 6 cubical inches of hydrogene were produced, a quantity always inferior to that evolved by the action of an equal portion of the metal upon water. In the distillation from 11 to 17 cubic inches of elastic fluid were evolved, and from 1.5 to 2. 5 grains of potassium regenerated.' p. 451.

When the products of the distillation of the olive coloured substance are collected at different periods, the proportion of the nitrogen to the hydrogen is found to diminish as the process advances; the first portions containing a greater, and the last a less proportion, than the gas evolved from ammonia by electricity. Supposing nitrogen to be decom

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