Experiments and Observations on Different Kinds of Air

by Joseph Priestley

Nitrous air is as much diminished both by iron filings, and also by liver of sulphur, when confined in quicksilver, as when it is exposed to water.

Distilled water tinged blue with the juice of turnsole becomes red on being impregnated with nitrous air; but by being exposed a week or a fortnight to the common atmosphere, in open and shallow vessels, it recovers its blue colour; though, in that time, the greater part of the water will be evaporated. This shews that in time nitrous air escapes from the water with which it is combined, just as fixed air does, though by no means so readily[14].

Having dissolved silver, copper, and iron in equal quantities of spirit of nitre diluted with water, the quantities of nitrous air produced from them were in the following proportion; from iron 8, from copper 6-1/4, from silver 6. In about the same proportion also it was necessary to mix water with the spirit of nitre in each case, in order to make it dissolve these metals with equal rapidity, silver requiring the least water, and iron the most.

Phosphorus gave no light in nitrous air, and did not take away from its power of diminishing common air; only when the redness of the mixture went off, the vessel in which it was made was filled with white fumes, as if there had been some volatile alkali in it. The phosphorus itself was unchanged.

There is something remarkable in the effect of nitrous air on insects that are put into it. I observed before that this kind of air is as noxious as any whatever, a mouse dying the moment it is put into it; but frogs and snails (and therefore, probably, other animals whose respiration is not frequent) will bear being exposed to it a considerable time, though they die at length. A frog put into nitrous air struggled much for two or three minutes, and moved now and then for a quarter of an hour, after which it was taken out, but did not recover. Wasps always died the moment they were put into the nitrous air. I could never observe that they made the least motion in it, nor could they be recovered to life afterwards. This was also the case in general with spiders, flies, and butterflies. Sometimes, however, spiders would recover after being exposed about a minute to this kind of air.

Considering how fatal nitrous air is to insects, and likewise its great antiseptic power, I conceived that considerable use might be made of it in medicine, especially in the form of clysters, in which fixed air had been applied with some success; and in order to try whether the bowels of an animal would bear the injection of it, I contrived, with the help of Mr. Hey, to convey a quantity of it up the anus of a dog. But he gave manifest signs of uneasiness, as long as he retained it, which was a considerable time, though in a few hours afterwards he was as lively as ever, and seemed to have suffered nothing from the operation.

Perhaps if nitrous air was diluted either with common air, or fixed air, the bowels might bear it better, and still it might be destructive to worms of all kinds, and be of use to check or correct putrefaction in the intestinal canal, or other parts of the system. I repeat it once more that, being no physician, I run no risk by such proposals as these; and I cannot help flattering myself that, in time, very great medicinal use will be made of the application of these different kinds of air to the animal system. Let ingenious physicians attend to this subject, and endeavour to lay hold of the new handle which is now presented them, before it be seized by rash empiricks; who, by an indiscriminate and injudicious application, often ruin the credit of things and processes which might otherwise make an useful addition to the materia and ars medica.

In the first publication of my papers, having experienced the remarkable antiseptic power of nitrous air, I proposed an attempt to preserve anatomical preparations, &c. by means of it; but Mr. Hey, who made the trial, found that, after some months, various animal substances were shriveled, and did not preserve their natural forms in this kind of air.

FOOTNOTES:

[13] The result of several of these experiments I had the pleasure of trying in the presence of the celebrated Mr. De Luc of Geneva, when he was upon a visit to Lord Shelburne in Wiltshire.