muft be found in the Air, fince intre Carcaffes are in a fhort time diffipated wholly therein. Laftly, Feffils of all kinds are found in the Foffils. Air, as Salts, Sulphurs, nay and Metals. The Atmosphere therefore may be confidered as a real Chaos of Bodies of all Sorts; and hence fo many extraordinary Phænomena and Effects of it; and the great Influence which it has on all chemical Operations. Dr. Boerhaave has often been led to think, that God created the two great Principles, Fire and elaftic Air, without gravity or tendency to any certain Point, equably diffufed thro' the whole Universe, and all the Syftems of things, with this Condition, that Fire fhould always be fo acting on Air, as that this could never remain at reft, or be in a ftate of abfolute Cold. From the Hiftory of Air, the Author proceeds to fome Experiments upon it, which illuftrate many of its Properties and Effects; as, that elaftic Air adheres to folid as well as fluid Bodies, and that it is found in Water, and may be procured out of the Subftance thereof, as alfo out of all other Fluids that it will enter and incorporate itself with Water exhaufted of its Air, tho' not with fuch as is faturated therewith. That Air is feparable from Water by Ebullition, alfo by Congelation; and by the admixture of alcaline Salts: and that Air is procurable out of the warm Juices of Animals, E. gr. Urine, &c. Air, how little fpace foever it seem to poffefs Air in Wain Water, when diffused thro' the minute Va-ter. cuities thereof, yet being extracted and collec-P. 523. ted together, poffeffes more room than the whole Body of Water did before. This the Author fhews by Experiment: and hence gathers, that Air, while imprisoned in Water, is not true Bb 3 Air 3 526. Air; nor has the fame phyfical Properties, as when difengaged from it, and collected together. Borelli and others were hence led into great Errors concerning the vital Action, and Of cillation of Air in the Blood and Juices of Animals. The Corpufcles of Air, by being difperfed, are hindered from operating: in effect, the expanfive Power of Air feems to arife hence, that the Particles mutually approach each other; so that when kept afunder, their action is prevented of course. Add, that Air while in feparate Particles will pass thro' the minutest Pores, fince we find that Water containing the ufual Proportion of Air, penetrates all Bodies, thro' which Water itself naturally paffes. But when the aerial Elements are collected, fo as to conftitute a Portion of vulgar Air; it becomes incapable of paffing Bodies, which it pervaded before. Thus the fmalleft, Bubble of Air is ftopped, where Water with the Air in it easily paffed.- Hence it may be inferred, that the Air intermixed with Fluids, as Chyle, Milk, Blood, Serum, Saliva, Bile or Urine, does not act in them by any Power belonging to common Air; nor can the Air diffufed thro' them difengage itself therefrom by any Diminution of the Weight of the Atmosphere, or any additional warmth which the Fluids in a healthy Body are capable of. The account of Air ends with fome Experiments, fhewing divers ways of procuring elastic Air from Bodies wherein it had before lain hid ; as from Vinegar, and Crabs-Eyes; from Chalk and Oil of Tartar per Deliquium; from Oil of Tartar and Vitriol; from Spirit of Nitre and Iron; from Spirit of Nitre and Oil of Carro ways; ways; and many other Bodies, either by Fermentation, Putrifaction, Diftillation or Burning. The whole clofes with fome Corollaries, concerning the Effects of Air in chemical Operations. The Article of Water is one of the finest in the Water, Book. This Fluid is of great importance in, 542. Chemistry; being intermixed with all Bodies, which come under chemical Confideration, partly per fe, and partly as contained in the Air. The driest Bodies, as Hartfhorn kept for half an Age, till as hard as Iron, will yield a Spirit which contains a good deal of Water: fo Stones and Tiles ground to Powder, and this expofed to the Fire, always yield a Proportion of Water. For a Characteristic of Water, whereby to Characters diftinguish when and where we meet it, the Au- of it. thor gives us the following Definition: That 66 by Water is meant a fluid, inodorous, infipid, pellucid, colourlefs Liquor, which "with a certain Degree of Cold congeals into "a hard, brittle, vitreous Subftance called Ice." The great Difficulty of afcertaining the Nature, and Conftitution of this Fluid, arifes from the impoffibility of having it pure, there being always other Bodies mixed with it; and no way of distinguishing, to which of them any difco- Contents. verable Property is owing. Thus in Water we always find Fire, alfo Air, and other Bodies diffolved by and incorporated with it. The Properties of Water are, 1°. Its Gravity, Properties the precife Quantity of which it is not easy to 547.. afcertain, by reafon of the extraneous Matters mixed with it, which being different in different Waters, makes a diverfity in their Weight. 2°. Fluidity, which depends on the Fire, and requires at least thirty-three Degrees of Heat, on Bb 4 Fab Kinds. Fahrenheit's Thermometer. This Degree of Warmth liquifies Water, and no further Heat, how vehement foever, renders it a whit more fluid. 3°. Immutability, its Particles being incapable either of being broken, bent, compress'd or the like. 4. Simplicity, whence Water has paffed, both with Chemists and other Philofophers, as the only Element, of which all Bodies are compofed. 5. Softness or Lenity, whence it may be applied without harm to the most exquifitely fenfible Parts of the Body. Thus warm Water becomes a capital Anodyne and Paregoric. 6o. Its folutive Power which extends to the diffolving of all Salts, both Vegetable, Animal, and Foffil, excepting fome metalline ones which it will not touch. Water infinuates into the Pores of Bodies, and thus increases both their Weight and Bulk ; and fometimes unites and incorporates with them, as is found in faline Bodies, alfo in Sulphur, Earths, and even the folid Parts of Animals, Oils, and Alcohol; where Water appears to make a confiderable Part of the Compofition. From the general Properties of Water, the Author proceeds to confider the different Species of it, and the Ufes: as Rain-Water, Spring Water, River-Water, and Pond-Water; the particular Characters, Qualities, Ufes, Origins, &c. of each whereof he purfues at large. The natural State of Water is its frozen, or icy State; out of which it is brought by Force Thawing. of Fire. Thawing is to be confidered as the Effect of a Menftruum, viz. Fire. Ule of Water. The Ufe of Water is great, as it is the Vehicle of Aliment, and the Inftrument of Life and Health in Animals, as well as Vegetables and Foffils. The Colours of Bodies alfo have, a great Dependance on it, as appears in Flow- Water indeed has been faid to be convertible Water #f into Earth by a Series of Diftillations; particu-convertible larly by Mr. Boyle, on whofe Authority many to Earth, have taken it for granted, and among the reft Sir Ifaac Newton. Dr. Boerhaave has made the Experiment with great care in Rain-Water, without finding any thing to countenance the Opinion; the Quantity of the Earth left after Diftillation of a large Quantity of Water by a gentle Fire, being exceedingly little: befide, a great deal of Water was loft in the Operation, tho the |