8

Pretended Compofition of Azotic Gas.

II.

On the Luminous Appearance faid to be exhibited by Phosphorus in Azotic Gas.

By DR. ALEXANDER NICHOLAS SCHERER, Counsellor of the Mines to his Serene Highness the Duke of Saxen Weimar*.

AT the time when the principles of the new theory were newly difcuffed, the enquiries

of chemists were employed upon fome of its chief affertions. Befides examining the experiments that metallic oxyds do emit oxygen gas during their reduction, attention was also paid to another, by which it was obferved, that the combustion of bodies in oxygen gas is always accompanied by a total abforption.

Mr. Goettling, who exerted his industry on fuch experiments, made use of the apparatus he employed in feveral experiments of the fame nature. He accidentally observed, that the phosphorus continues to fhine for fome time in the azotic gas, which remains after its combustion in atmospheric air. What he principally observes on this head is, that phofphorus fhines very strongly in azotic gas, even more fo than in atmospherical air; that it is converted into phosphoric acid by this procefs; and that the azotic gas totally disappears. Hence he was led to infer, that azotic gas muft contain oxygen, as well as the oxygen gas itself does. But if so, what is the difference between these two species of gas? This question was apparently solved by another experiment he made. Phofphorus does not shine fo well in oxygen gas at a low temperature, as it does in the azotic; and when phofphorus gives light in atmospherical air, it is always with extrication of heat; whereas the light is not attended with heat in azotic gas. He concludes therefore, that the azotic gas confifts of oxygen combined with light, in the fame manner as, on the other hand, the oxygen gas confifts of that principle combined with caloric; and moreover that caloric has a ftronger affinity to oxygen than light has.-On this Mr. Goettling builds an entirely new theory of chemistry, from the confideration that the new mixture of azotic gas, which he pretends to have discovered, does not admit of the hitherto adopted way of explaining its influence.

Mr. Goettling has explained these facts at large in his Beytrag zur Berichtigung der antiphlogiftifchen Chemie. Weimar 1794. This work was univerfally well received, and fome were inclined to give it full credit without further examination. Mr. Goettling himself has publicly explained his new theory, and adapted the whole of his chemical lectures to that 'system. A few philofophers only ventured to offer their doubts concerning it. Among these are Dr. Eimbke; Intelligenzblat der allg. litt. Zeit. 1794, No. 92, and Yelin; Erlang. gel. Zeit. 1794, No. 80. The former observed, that when phosphorus had ceased to shine in atmospheric air, it would afford no more light in the remaining azotic gas. The second found, that phosphorus, after undergoing a very long continued heat in atmospherical air, does alfo leave behind an aëriform refidue, in which the phosphorus will by no means fhine any longer.

At this time I had commenced a public course of lectures on Chemistry. I therefore thought myself obliged to make new enquiries for the purpose of giving an impartial ac

* Received from the Author.

count

Controverfy respecting Phosphorus in Azotic Gas.

count of this new difcovery; but to avoid being led into error by individual obfervations, as is frequently the cafe with experiments, I joined Dr. Jaeger from Stuttgard, who was just then visiting me on a journey. We made a great number of experiments together, which we endeavoured to diverfify in every poffible manner, in order to difcover all the concurrent circumftances. In the Jena. gel. Zeit. 1794, No. 113, we published a fort account of one of the chief occurrences; but the full defcription of the refults from our inveltigations fome time after was given in the following book, Uber das Leuchten des "Phofphors im atmospherifchen Stickgas. Weimar 1795. To this work we have added another treatife on Goettling's theory by Dr. Pfaff.

The chief aim of this enquiry was to fhew by decifive experiments, whether phosphorus does really give light in azotic gas, and whether it be totally decompofed by it? Neither of these two we could find by any process of operation. We made comparative experiments over water and over quickfilver, and clearly perceived that Mr. Goettling, having closed his veffels merely by water, could not avoid a fource of error. We fpared no exertions to investigate as exactly as poffible the method of preparing azotic gas, and by that means discovered a variety of interefting circumftances. We always found that the fumes of phosphoreous acid, rifing by a momentary combustion of phosphorus in atmospherical air, did fo far envelope the remaining portion of oxygen, that the luminous appearance from the union of this with another part of the phofphorus could not be again produced until the water had abforbed the acid fumes. We always found however that this light was of fhort duration, accompanied by a very inconfiderable diminution of the claftic fluid, and that it was altogether impoffible to cause the phosphorus to emit any more light in the remaining air. On this account we had every reafon to confider this as pure azotic gas, and to declare those experiments of Mr. Goettling incorrect, from which the combustion of phofphorus was faid to take place in the purest azotic gas.

To all this Mr. Goettling made no reply, except that he gave an anfwer in the Intelligenzbl. der allgem. Literat. Zeit. 1794, No. 117, to our first very fhort notice, tending to place the whole investigation in an unfavourable point of view. Of our treatise, though printed above two years ago, he has not yet taken any notice.

Soon afterwards Mr. Girtanner took fome pains to explain the refult of Mr. Goettling's experiments, Ibid. 1795, No. 23, by fuppofing the azotic gas employed had contained fome water, which was decompofed by the phofphorus. He did not, however, take the trouble to ascertain by experiments, whether phosphorus does really give light in azotic gas thoroughly freed from oxygen. Mr. Goettling replied to this, by alledging, that if the water which exists diffolved in the gases were the cause of this light, the phosphorus ought also to emit light in oxygen gas, which according to his experiments did not take place. lbid. No. 27. He afterwards published a more ample elucidation of the short answer here related in the Almanach fuer Scheide Kuenfiler, 1795, afferting that the luminous appearance of phosphorus could not be obtained in an azotic gas, which had been procured by a long continued heating of the phosphorus in atmospheric air, because in that cafe the phosphorus mixes with the azotic gas, and prevents it from maintaining the light. He added, that the gas thus circumftanced is found to recover this property by adding a few drops of an acid. But he was by no means aware that his obfervation contained a very important objection against his own theory. For if, according to that theory, azotic C

VOL. II.-APRIL 1798.

gas

10

Controverfy refpecting Phosphorus in Azotic Gas.

gas be really a compound of oxygen and light, why should the phosphorus, on being mixed with it, cease to act on its oxygen? Ought it not rather to do this more speedily when the cohesion of its parts is deftroyed? Befides which, the addition of acids is not fair, because more acid than is neceffary to faturate the phofphorus diffolved in it, may in this way become united with the azotic gas. Thus I have found that the phosphorus, which does not shine in puré carbonic acid gas, begins to give light in that medium as foon as a fmall portion of acid is added. The answer given by Dr. Jaeger was more explicit. He discovered in particular, that the volume of the azotic gas was never diminished when the luminous appearance of the phosphorus was reproduced by means of acids. Gren's Neues Journal der Phyfik. B. II.

It was not long after, that Profeffor Lampadius published his experiments on this fubject. At first he seemed to find every thing exactly as defcribed by Mr. Goettling, Ibid. B. I.; but foon afterwards he made the interesting discovery, that by a careful decompofition of atmospherical air, by means of nitrous gas, azotic gas may be procured, so free from oxygen, that phosphorus cannot be made to fhine in it. Sammlung pract. chemisch. Abhandl. B. I.

Profeffor Hildebrandt repeated Mr. Goettling's experiments with the greatest care. Crell's Annal. 1796, B. I. These experiments are, no doubt, the most exact of any that were made for this purpose. He has perfectly confirmed our experiments. He has proved this beyond all question, by several experiments, of which I fhall mention but one.-In the fame azotic gas in which phosphorus had ceased to shine, and fresh phosphorus would not afford light, the luminous appearance took place as foon as oxygen gas was added. But this lafted no longer than till the latter was confumed; for there was precisely as much of the whole volume of the mixture abforbed, as made up the quantity of the oxygen gas that was added.

There are several well known papers on this subject, in the Annales de Chimie, written by French chemists; but none of their authors have paid the least attention to what has been tranfacted on this matter: a circumstance which I have thought proper to be mentioned in this place. But they have added the important fact, that phosphorus is foluble in azotic gas. Probably they had no intelligence of what has been written about it in Germany; and as this appears to me to be the cafe with England, I confidered it of fome importance, to give the fhorteft poffible view of the chief points of thefe tranfactions. I have endeavoured to give a more ample detail of all the particular facts, as far as they were known down to October 1796, in a work of mine, equally unknown in this country: Nachtrage zu den Grunzuegen der neuern chemischen Theorie, pag. 326—349, in which the whole extent of these enquiries may be seen with greater ease by the systematical arrangement of the experiments. It is It is to be hoped that the dispute will end here, and that the facts, (1.) that no shining of the phosphorus can in any respect take place in fuch azotic gas as is quite free of oxygen, and (2.) that it cannot be made to shine unless some other body be added which is capable of affording oxygen,—will be admitted as incontrovertibly established.

LONDON, Feb. 27, 1798.

III. On

New Weather-Inftrument.

III.

On M. LAZOWSKI's new Rarometer, or Weather Inftrument. By a Correspondent.

SIR,

To Mr. NICHOLSON, Editor of the Philofophical Journal.

II

Kendal, Jan. 31, 1798.

THE following experimental effay is too trifling to require an introductory apology,

were it not for the high name of Dr. Hutton, which unavoidably occurs in the courfe of it, as the subject of the prefent communication was first suggested by a paragraph in his Mathematical and Philofophical Dictionary, published in 1795.

When any thing new in fcience is announced, it ought to be made public as generally and ast fpeedily as poffible. In this refpect Dr. Hutton has only done his duty as a compiler, in bringing the English reader acquainted with the supposed discovery of a new inftrument capable of indicating approaching changes of the weather. On the other hand, when any thing novel is communicated to the lovers of science, it is the bufinefs and undoubted right of every friend to enquiry, not to receive the propofal on bare authority, but to fubject it to the teft of argument and experiment, in order to establish it as a fact, or refute it as an error. Having premifed thus much in my own vindication, I will in the next place tranfcribe the paragraph alluded to above. "To the foregoing may be added a new fort of Barometer, or Weather Inftrument, by the found of a wire. This is mentioned by M. Lazowski, in his Tour through Switzerland: it is as yet but in an imperfect flate, and was lately discovered there by accident. It seems that a clergyman, though near-fighted, often amufed himself with firing at a mark, and contrived to ftretch a wire fo as to draw the mark to him to fee how he had aimed. He obferved that the wire fometimes founded as if it vibrated like a mufical cord; and that after fuch foundings, a change always enfuedin the ftate of the atmosphere, from whence he came to predict rain, or fine weather, &c.*"

After perusing this fingular narrative, I found myself at a lofs in attempting to refer the difcovery to any known clafs of phenomena, or to explain it by the affections of the atmosphere, confidered as depending on the barometer, electricity, or even the hygrometer, without admitting a supposition, which is not discountenanced by the preceding report, viz. that one end of the wire was fixed to a frame of wood, while the other end was ftretched over a nail or metal pin in the fame by a weight. Under thefe circumftances, it appeared not impoffible, that the wood-work might contract and expand from fucceffive variations in the air's humidity, thereby putting the pin in motion, which may be supposed to scratch the wire, and give rife to the found in queftion. But with a view to afcertain if a vibratory motion can be excited in metallic ftrings by any other change in the state of the atmosphere, I fixed a number of copper and iron wires, in the beginning of April 1795, in an open place they were different lengths, from three to fix feet, and of different diameters, varying from the thickness of a fine thread to the fize of a small cord; they were all ftretched by metal pins, resembling those used in a harpsichord, and so disposed as to make various angles with the meridian and the horizon. The apparatus, being thus completed,

**See Hutton's Dictionary, article Barometer.

C 2

was

12

Weather-Inftrument. Eolian Harp, &c.

was carefully attended to through the fummer, particularly when the aspect of the fky and ftate of the barometer feemed to predict an approaching change; but the enquiry was fruitlefs, the promised found was never heard; nor did any other circumftance worthy notice occur, except that fome of the smallest wires snapped occafionally in the cold nights of the fpring. The failure of this experiment feems to confirm the fuppofition that M. Lazowski's instrument is at best but an imperfect Hygrometer, and that it does not promise any new discovery relative to the properties or compofition of the atmosphere *.

J. G.

IV.

Obfervations on Scylla and Charybdis t. By the Abbé LAZZARO SPALLANZANI, Profeffor of Natural History at Pavia, F.R. S. &c. &c.

SCYLLA and Charybdis, according to the fables of the poets, are two sea monsters

whofe dreadful jaws are continually diftended to fwallow unhappy mariners; the one fituated on the right, and the other on the left extremity of the Strait of Messina, where Sicily fronts Italy.

Dextrum Scylla latus, lævum implacata Charybdis

Obfidet: atque imo barathri ter gurgite vaftos

The paffage in Dr. Hutton's Dictionary will admit of the fenfe, that the obferver (who perhaps never took notice of his wire, except when bufied in the amusement there mentioned) did not hear any spontaneous found, but merely perceived a mufical vibration at certain times during the act of drawing the mark along the wire, which must have agitated it. This might arife from tenfion, by fome hygrometric change in the fituation of the points of fupport. It may be remarked, that a wire for the ufe the clergyman applied it to must have been much longer than fix feet; and that it was probably less stretched than the wires expofed by my correfpondent.

If the founds were spontaneous, the fact will be referable to the Eolian harp of Merfennus, fince re-invented by Ofwald. The inftrument confifts of a founding board about two feet or more in length, upon which ten or twelve (catgut) ftrings of equal length but different thickness are tuned in unifon, at as low a pitch as the fmalleft of the ftrings can bear. When this is placed in a current of air, fuch for example as paffes through a window partly opened, it emits a variety of contemporaneous and fucceffive tones, which from their changes in melody, harmony, and swell, and a certain wild ftrangeness in the whole effect, rivet the attention, and fometimes afford exquifite pleasure. The Eolian harp has been celebrated by Thomson and other poets.' I have not made experiments to analyse its mode of operation; but am difpofed to think, (1) that it can only give the trumpet notes; (2) that the note to be afforded by any one string depends on the quantity of the impulfe of the wind being greatest near one end of that string; (3) that the fame quantity and direction of impulfe will agitate a longer portion of the flack small string than of the tenfer thick ftring, fo that in the vibratory fubdivifions the smaller string will give the graver tone; (4) that a powerful tone drawn from one ftring may difpofe the other strings to vibrate unifons, fifths, thirds, octaves, and other concords, more or lefs remote according to the circumstances.

If M. Lazowski's wire acted upon the principle of the Eolian harp, it might be prefumed that the recurrence as well as the nature of the found emitted would be governed by the force and angle of direction of the wind; and, if so, much would depend on the expofure the direction and the tenfion of the wire. Whether on this fuppofition it could afford any more certain indication of approaching change of weather, than is usually ob-. tained from a fimple obfervation by the wind vane, must be decided by facts, if fuch should hereafter appear. N. Travels in the Two Sicilies. English Transl. IV. 168. Sorbet

I