The Ear-wig, the great Staphylinus, the great black lowsy Beetle, and some other Insects would seem unconcerned at the Vacuum a good while, and lie as dead; but revive in the Air, although some had lain sixteen Hours in the exhausted Receiver.
Snails bear the Air Pump prodigiously, especially those in Shells; two of which lay above twenty four Hours, and seemed not much affected. The same Snails I left in twenty eight Hours more after a second Exhaustion, and found one of them quite dead, but the other revived.
Frogs and Toads bear the Pump long, especially the former. A large Toad, found in the House, died irrecoverably in less than six Hours. Another Toad and Frog I put in together, and the Toad was seemingly dead in two Hours, but the Frog just alive. After they had remained there eleven Hours, and seemingly dead, the Frog recovered in the open Air, only weak, but the Toad was quite dead. The same Frog being put in again for twenty seven Hours, then quite died.
The Animalcules in Pepper-Water remained in Vacuo twenty four Hours. And after they had been exposed a Day or two to the open Air, I found some of them dead, some alive.
[g] That the Air is the principal Cause of the Vegetation of Plants, Borelli proves in his excellent Book De Mot. Animal. Vol. 2. Prop. 181. And in the next Proposition, he assureth, In Plantis quoque peragi Aeris respirationem quandam imperfectam, à quâ earum vita pendet, & conservatur. But of this more when I come to survey Vegetables.
Some Lettice-Seed being sown upon some Earth in the open Air, and some of the same Seed at the same time upon other Earth in a Glass-Receiver of the Pneumatick Engine, afterwards exhausted of Air: The Seed exposed to the Air was grown up an Inch and half high within Eight Days; but that in the exhausted Receiver not at all. And Air being again admitted into the same emptied Receiver, to see whether any of the Seed would then come up, it was found, that in the Space of one Week it was grown up to the Height of two or three Inches. Vid. Phil. Trans. No. 23. Lowth. Abridg. Vol. 2. p. 206.
[h] In volucribus pulmones perforati aerem inspiratum in totam ventris cavitatem admittunt. Hujus ratio, ut propter corporis truncum Aere repletum & quasi extensum, ipsa magis volatilia evadant, faciliusque ab aere externo, proper intimi penum, sustententur. Equidem pisces, quò leviùs in aquis natent, in Abdomine vesicas Aere inflatas gestant: pariter & volucres, propter corporis truncum Aere impletum & quasi inflatum, nudo Aeri incumbentes, minus gravantur, proindeque levius & expeditiùs volant. Willis de Anim. Brut. p. 1. c. 3.
[] Fishes by reason of the Bladder of Air within them, can sustain, or keep themselves in any Depth of Water: For the Air in that Bladder being more or less compressed, according to the Depth the Fish swims at, takes up more or less Space; and consequently, the Body of the Fish, part of whose Bulk this Bladder is, is greater or less according to the several Depths, and yet retains the same Weight. Now the Rule de Insidentibus humido is, that a Body, that is heavier than so much Water, as is equal in Quantity to the Bulk of it, will sink, a Body that is lighter will swim; a Body of equal Weight will rest in any part of the Water. By this Rule, if the Fish, in the middle Region of the Water, be of equal Weight to the Water, that is commensurate to the Bulk of it, the Fish will rest there, without any Tendency upwards or downwards: And if the Fish be deeper in the Water, the Bulk of the Fish becoming less by the Compression of the Bladder, and yet retaining the same Weight, it will sink, and rest at the Bottom. And on the other side, if the Fish be higher than the middle Region, the Air dilating it self, and the Bulk of the Fish consequently increasing, but not the Weight, the Fish will rise upwards and rest at the top of the Water. Perhaps the Fish by some Action can emit Air out of its Bladder——, and, when not enough, take in Air,——and then it will not be wondred, that there should be always a fit Proportion of Air in all Fishes to serve their Use, &c. Then follows a Method of Mr. Boyl to experiment the Truth of this. After which, in Mr. Lowthorp’s Abridgment, follow Mr. Ray’s Observations. I think that——hath hit upon the true Use of the Swimming-Bladders in Fishes. For, 1. It hath been observed, that if the Swimming-Bladder of any Fish be pricked or broken, such a Fish sinks presently to the Bottom, and can neither support or raise it self up in the Water. 2. Flat Fishes, as Soles, Plaise, &c. which lie always grovelling at the Bottom, have no Swimming-Bladders that ever I could find. 3. In most Fishes there is a manifest Chanel leading from the Gullet——to the said Bladder, which without doubt serves for the conveying Air thereunto.——In the Coat of this Bladder is a musculous Power to contract it when the Fish lifts. See more very curious Observations relating to this Matter, of the late great Mr. Ray, as also of the curious anonymous Gentleman in the ingenious Mr. Lowthorp’s Abridgment, before cited, p. 845. from Phil. Trans. N. 114, 115.
[k] Among the Engines in which the Air is useful, Pumps may be accounted not contemptible ones, and divers other Hydraulical Engines, which need not to be particularly insisted on. In these the Water was imagined to rise by the power of Suction, to avoid a Vacuum, and such unintelligible Stuff; but the justly famous Mr. Boyl was the first that solved these Phænomena by the Weight of the Atmosphere. His ingenious and curious Observations and Experiments relating hereto, may be seen in his little Tract, Of the Cause of Attraction by Suction, and divers others of his Tracts.
[l] It would be endless to specify the Uses of the Air in Nature’s Operations: I shall therefore, for a Sample only, name its great Use to the World in conserving animated Bodies, whether endowed with animal or vegetative Life, and its contrary Quality of dissolving other Bodies; by which means many Bodies that would prove Nuisances to the World, are put out of the Way, by being reduced into their first Principles, (as we say), and so embodied with the Earth again. Of its Faculty as a Menstruum, or its Power to dissolve Bodies; I may instance in Crystal Glasses, which, with long keeping, especially if not used, will in Time be reduced to a Powder, as I have seen. So divers Minerals, Earths, Stones, Fossil-Shells, Wood, &c. which from Noah’s Flood, at least for many Ages, have lain under Ground, so secure from Corruption, that, on the contrary, they have been thereby made much the stronger, have in the open Air soon mouldered away. Of which last, Mr. Boyl gives an Instance (from the Dissertation de admirandis Hungar. Aquis) of a great Oak, like a huge Beam, dug out of a Salt Mine in Transylvania, so hard, that it would not easily be wrought upon by Iron Tools, yet, being exposed to the Air out of the Mine, it became so rotten that in four Days it was easy to be broken, and crumbled between one’s Fingers. Boyl’s Suspic. about some hid. Qual. in the Air, p. 28. So the Trees turned out of the Earth by the Breaches at West-Thurrock and Dagenham, near me, although probably no other than Alder, and interred many Ages ago in a rotten oazy Mold, were so exceedingly tough, hard, and found at first, that I could make but little Impressions on them with the Strokes of an Ax; but being exposed to the Air and Water, soon became so rotten as to be crumbled between the Fingers. See my Observations in Philos. Transact. Nᵒ. 335.