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ing as discourse, of a tree in one of the Tercera Islands, that perpetually distils water, so as to be of some convenience to the inhabitants *: and Paracelsus says, there is a plant called Rosa Solis, or Ross Solis, that remains full of dew in the noon-day heat, when all other herbs are dry †. And if these instances are true, they might prove of noble use, and very worthy of farther examination. But for those honey-dews, which, like manna, are found upon oak-leaves in the month of May; we judge they are not made or condensed by any consent or peculiarity in the oak-leaf, but that they fall upon other leaves also, and are only catched and detained upon the leaves of the oak, because these are closer, and not so spongy as most other leaves.

As to heat, men have a large supply, and a great command thereof, though some of its most necessary particulars still remain to be observed, and enquired into, notwithstanding the boasts of the chemists. For though the works of intense heat are much sought after and admired, yet the effects of a slow heat (which are chiefly those produced by nature) remain unexperienced and concealed. Hence we see by the violent heats

* See Dr. Sprat's History of the Royal Society. ↑ See the Sylva Sylvarum.

now commonly used, the spirits of bodies are greatly exalted, as in mineral acid spirits, and certain chemical oils, but the tangible parts are hardened, and sometimes fixed, with the loss of the volatile ones. And thus the homogeneous parts are separated, and the heterogeneous grossly incorporated and mixed together, whilst the structure and more subtile texture of compound bodies, is, by this means, confounded and destroyed, so that the effects of a milder heat ought, by all means, to be tried and discovered; whence much more subtile mixtures and regular textures, or structures of bodies, might be procured in imitation of nature and the works of the sun, according to what we intimated above*. For the operations of nature are performed by much slower degrees, or much smaller steps and portions at a time, and by more exquisite and various positions or arrangements, than the works of fire, as it is now employed. And it is then that the human power may seem truly enlarged, when, by heats and artificial ways, the works of nature may be exactly imitated, or expressed in appearance, perfected in virtue, and varied in number; to which we may also

add, accelerated in time t.

Thus the rust of iron

is a long while in making, but expeditiously ob

*See Aph. 35.

+ See the Sylva Sylvarum.

tained in the artificial Crocus Martis. And the same is to be understood of verdigrease and ceruse. Crystal is produced by a long process, but glass by a short one; stones grow slow, but bricks are presently made.

And all the diversities of heat, with their different effects, are, with diligence and industry, to be sought out and collected from all quarters, viz. (1.) those of the heavenly bodies, by their direct rays; and as they are reflected, refracted, and united by burning-glasses*: (2.) those of lightning, flame, and coal-fires: (3.) Fires of different material: (4.) open fires, close fires, straitened and streaming fires; or fires modified by all the various structures of furnaces: (51) Fire animated by the blast: (6.) Fire left to itself, unexcited: (7.) Fire removed to a greater or less distance: (8.) Fire acting through different mediums: (9.) moist heats, as those of the Balneum Mariæ, and the dunghill; external and internal animal heats; compressed hay, &c. (10.) dry heats; as of ashes, lime, sand; and, in short, heats of all kinds, with their various degrees +.

* See the experiments made with the Duke of Orleans's burning lens, by M. Homberg; Memoir. de l'Acad. Roy. An. 1702. See also the Philosophical Transactions, and German Ephemerides, to the same purpose.

† See the New Atlantis, in a collection of the Author's Miscellaneous Writings, printed uniform with the present Work.

Above all, the enquiry and discovery of the effects and productions of heat, continued and remitted gradually, regularly, and periodically, at due distances, and with due continuance, should be attempted; for this stated inequality is a true offspring of the heavens, and the mother of generation. Nor is any thing extremely great and commanding to be expected from a vehement, hasty, and subsultory heat. This appears plainly in vegetables; and again in the wombs of animals, where there is a great inequality of heat, from the motion, the sleep, the food, and the passions of the female in gestation; and, lastly, the same inequality takes place in the matrices of the earth, where metals and minerals are formed.

This renders the unskilfulness of some modern alchemists the more remarkable, who expect to obtain their end by means of an athanor, or the equable heats of lamps, &c. kept burning in one constant manner*. And so much, at present, for the works and effects of heat. Nor is it yet the season to examine these particulars thoroughly, before the forms and textures of bodies shall have been farther discovered and brought to light, for it is then that instruments are to be sought out, applied, and adapted, when the ex

See the Sylva Sylvarum, under the article Gold,

amples, views, and designs, are fixed and determined.

The fourth means of practice, viz. continuance, is the provider and dispenser of nature. We call that continuance, when a body is left for a considerable time to itself, guarded and defended from all external force, in which state the intestine motions discover, and finish, or perfect their own course, whilst the extraneous and adventitious motions are excluded, for the works of time are much more subtile than the works of fire*. Wine can no way be so well clarified by the fire, as by time, nor are the incinerations made by fire so exquisite as the resolutions, consumptions, and decays of time. The sudden and precipitate incorporations and mixtures made by fire, are far inferior to those made by time. And the different and various textures, which bodies endeavour at by continuance, as in the case of putrefactions, are destroyed by fire, or a violent heat t.

It may be here proper to observe, that the motions of bodies perfectly included, or close confined in vessels, suffer something of violence, as this imprisonment hinders the spontaneous

* See the Sylva Sylvarum, under the articles Heat, Preservation, and Putrefaction.

+ See the Sylva Sylvarum.

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