XXIV. Experiments and Obfervations on the inflammable Air breathed by various Animals. By the Abbé Fontana, Director of the Cabinet of Natural History belonging to his Royal Highness the Grand Duke of Tuscany; communicated by John Paradise, Efq. F. R. S..

Read March 11, 1779.

PHILOSOPHERS believed, till lately, that inflam

mable air had the power of killing animals who breathed it. Dr. PRIESTLEY, to whom we are much indebted for many discoveries and obfervations relative to inflammable air, made in confequence of Mr. CAVENDISH'S excellent paper on that fubject, affures us, that inflammable air caufes the death of animals as readily as fixed air, and that animals die convulfed in it. The doctor adds, that water absorbed about one quarter of the inflammable air fhaken in it, after which a mouse lived in it as long as it would have lived in an equal quantity of common air. This air breathed by the mouse was still inflammable, though not fo much as

before.

Mr.

Mr. SHEELE, who has made various important observations in chemistry, on the contrary afferts, that inflammable air not only does not kill the animals who breathe it, but that it is even good and innocent air. He relates fome experiments to which it feems that nothing can be oppofed, and they appear to contradict Dr. PRIESTLEY'S obfervations. Mr. SHEELE has breathed inflammable air contained in a bladder, without receiving any hurt.

Seeing then that the experiments of these celebrated perfons contradicted each other, I began to suspect that they might poffibly be all true; and that their fo contradictory effects might be owing to fome circumstance not yet attended to.

In order to follow fome method in my researches about a point fo delicate, and which fo nearly interests human life, I first of all thought of affuring myself, whether or no animals could breathe inflammable air with impunity, when the receivers that contained it were immerfed in quickfilver. To this end, I introduced inflammable air, extracted both from zinc and iron, by means of the vitriolic acid, into various tubes filled with quickfilver, in which the air entered pretty free from moisture. I then introduced various birds into those tubes, and observed that they died in a few minutes

I

time,

time, but without any apparent fign of convulfions. Thefe experiments, having been often repeated, were conftantly attended with the fame event.

Being affured, beyond any doubt, that the inflammable air obtained from zinc or iron, and made to pafs through quickfilver, was fatal to animals; I next wifhed to obferve, whether it retained the fame properties when it had paffed through water; in which cafe the volatile fulphurous acid, or other vapour, is abforbed by the water; but, on trying the experiments, I found that the birds died under these circumftances as under the others (though not quite fo foon) fhewing likewise fome figns of convulfion. I introduced some of this fame air that had paffed through water into a glass tube full of quickfilver, by a method which makes the air lofe all its moisture. The birds died in it in the fame manner as when the experiment was tried upon water. In all these cafes the air after the animals had died in it was ftill inflammable, nor did its exploding properties feem to have been at all diminished.

The inflammable air extracted from zinc, and that extracted from iron, is fatal to animals even after it has been shaken in water for a minute's time, or fomething longer. By fhaking it a long time, it becomes in fome measure respirable; but then it is decompofed in a great

mcafure,

measure, and becomes of another kind, although it still preferves the properties of being inflammable, but in a fmaller degree,

Not only birds but also quadrupeds die in inflammable air (though not so soon) and fhew some figns of being convulfed.

It seems very strange, that Mr. SHEELE could breathe inflammable air with impunity, when animals obliged to breathe it were killed in a very short time. Admitting his experiments to be true, there remains nothing to be faid, but that the inflammable air in which animals die does not occafion death because it is conveyed to the lungs, but because it affects some other organs of the animal body exposed to that air, and neceffary to animal life. It is not impoffible to occafion death by affecting the very fenfible nerves of the nose; it being well known, that various liquors, as very concentrated volatile alkaly, &c. if they are inspired through the nose, immediately affect the fenfes, and occafion death if they continue to act upon the pituitary brane.

mem

In order, therefore, to try whether inflammable air killed, only because it was inspired through the nose, I stopped very accurately the nofes of various birds with foft wax, and in this manner I introduced them into

receivers