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three or four foot under the earth in a vault, or in a conservatory of snow, the snow being made hollow about the bladder; and after some fortnight's distance, see whether the bladder be shrunk; for if it be, then it is plain that the coldness of the earth or snow hath condensed the air, and brought it a degree nearer to water: which is an experiment of great consequence. Experiment solitary touching congealing of water
into crystal. 364. It is a report of some good credit, that in deep caves there are pensile crystals, and degrees of crystal that drop from above; and in some other, though more rarely, that rise from below: Which though it be chiefly the work of cold, yet it that water that passeth through the earth, gathereth a nature more clammy, and fitter to congeal and become solid than water of itself. Therefore trial would be made, to lay a heap of earth, in great frosts, upon a hollow vessel, putting a canvass between, that it falleth not in :'and pour water upon it, in such quantity as will be sure to soak through ; and see whether it will not make a harder ice in the bottom of the vessel, and less apt to dissolve than ordinarily. I suppose also, that if you make the earth narrower at the bottom than at the top, in fashion of a sugar-loaf reversed, it will help the experiment. For it will make the ice, where it issueth, less in bulk; and evermore smallness of quantity is a help to version. Experiment solitary touching preserving of rose
leaves both in colour and smell. 365. Take damask roses, and pull them; then dry them upon the top of a house, upon a lead or terras, in the hot sun, in a clear day, between the hours only of twelve and two, or thereabouts. Then put them into a sweet dry earthen bottle, or a glass, with narrow mouths, stuffing them close together, but without bruising: stop the bottle or glass close, and these roses will retain not only their smell perfect, but their colour fresh, for a year at least. Note, that
nothing doth so much destroy any plant, or other body, either by putrefaction orarefaction, as the adventitious moisture which hangeth loose in the body, if it be not drawn out. For it betrayeth and tolleth forth the innate and radical moisture along with it when itself goeth forth. And therefore in living creatures, moderate sweat doth preserve the juice of the body. Note, that these roses, when you take them from the drying, have little or no smell ; so that the smell is a second smell, that issueth out of the flower afterwards. Experiments in consort touching the continuance
of flame. 366. The continuance of flame, according unto the diversity of the body inflamed, and other circumstances, is worthy the inquiry; chiefly, for that though flame be almost of a momentary lasting, yet it receiveth the more, and the less : we will first therefore speak at large of bodies inflamed wholly and immediately, without any wick to help the inflammation. A spoonful of spirit of wine, a little heated, was taken, and it burnt as long as came to a hundred and sixteen pulses. The same quantity of spirit of wine, mixed with the sixth part of a spoonfúl of nitre, burnt but to the space of ninety-four pulses. Mixed with the like quantity of bay-salt, eighty-three pulses. Mixed with the like quantity of gunpowder, which dissolved into a black water, one hundred and ten pulses. A cube or pellet of yellow wax was taken, as much as half the spirit of wine, and set in the midst, and it burnt only to the space of eighty-seven pulses. Mixed with the sixth part of a spoonful of milk, it burnt to the space of one hundred pulses; and the milk was curdled. Mixed with the sixth part of a spoonful of water, it burnt to the space of eighty-six pulses; with an equal quantity of water, only to the space of four pulses. A small pebble was laid in the midst, and the spirit of wine burnt to the space of ninety-four pulses. A piece of wood of the bigness of an arrow, and about a finger's length, was set up in the midst, and the
spirit of wine burnt to the space of ninety four pulses. So that the spirit of wine simple endured the longest; and the spirit of wine with the bay-salt, and the equal quantity of water, were the shortest.
367. Consider well, whether the more speedy going forth of the flame be caused by the greater vigour of the flame in burning; or by the resistance of the body mixed, and the aversion thereof to take flame: which will appear by the quantity of the spirit of wine that remaineth after the going out of the flame. And it seemeth clearly to be the latter; for that the mixture of things least apt to burn, is the speediest in going out. And note, by the way, that spirit of wine burned, till it go out of itself, will burn no more; and tasteth nothing so hot in the mouth as it did ; no, nor yet sour, as if it were a degree towards vinegar, which burnt wine doth; but flat and dead.
368. Note, that in the experiment of wax aforesaid, the wax dissolved in the burning, and yet did not incorporate itself with the spirit of wine, to produce one flame; but wheresoever the wax floated, the flame forsook it, till at last it spread all over, and put the flame quite out,
369. The experiments of the mixtures of the spirit of wine inflamed, are things of discovery, and not of use: but now we will speak of the continuance of flames, such as are used for candles, lamps, or tapers; consisting of inflammable matters, and of a wick that provoketh inflammation. And this importeth not only discovery, but also use and profit; for it is a great saving in all such lights, if they can be made as fair and bright as others, and yet last longer. Wax. pure made into a candle, and wax mixed severally into candle-stuff, with the particulars that follow; viz. water, aqua vita, milk, bay-salt, oil, butter, nitre, brimstone, saw-dust, every of these bearing a sixth part to the wax; and every of these candles mixed, being of the same weight and wick with the wax pure, proved thus in the burning and lasting. The swiftest in consuming was that with saw-dust; which first burned fair till some part of the candle was consumed, and the dust gathered about the snaste; but then it made the snaste big and long, and to burn duskishly, and the candle wasted in half the time of the wax pure. The next in swiftness were the oil and butter, which consumed by a fifth part swifter than the pure wax. Then followed in swiftness the clear wax itself. Then the bay-salt, which lasted about an eighth part longer than the clear wax, Then followed the aqua vita, which lasted about a fifth part longer than the clear wax. Then followed the milk, and water, with little difference from the
aqua vita, but the water slowest. And in these four last, the wick would spit forth little sparks. For the nitre, it would not hold lighted above some twelve pulses: but all the while it would spit out portions of flame, which afterwards would go out into a vapour. : For the brimstone, it would hold lighted much about the same time with the nitre; but then after a little while it would harden and cake about the snaste; so that the mixture of bay-salt with wax will win an eighth part of the time of lasting, and the water a fifth.
370. AFTER the several materials were tried, trial was likewise made of several wicks; as of ordinary cotton, sewing thread, rush, silk, straw, and wood. The silk, straw, and wood, would flame a little, till they came to the wax, and then go out: of the other three, the thread consumed faster
than the cotton, by a sixth part of time : the cotton next, then the rush consumed slower than the cotton, by at least a third part of time. For the bigness of the flame, the cotton and thread cast a flame much alike; and the rush much less and dimmer. Query, whether wood and wicks both, as in torches, consume faster than the wicks simple ?
371. WE have spoken of the several materials, and the several wicks : but to the lasting of the flame it importeth also, not only what the material is, but in the same material whether it be hard, soft, old, new, etc. Good housewives, to make their candles burn the longer, use to lay them, one by one, in bran or flour, which make them harder, and so they consume
the slower : insomuch as by this means they will outlast other candles of the same stuff almost half in half. For bran and flour have a virtue to harden; so that both age, and lying in the bran, doth help to the lasting. And we see that wax candles last longer than tallow candles, because wax is more firm and hard. :: 372. The lasting of flame also dependeth upon the easy drawing of the nourishment; as we see in the Court of England there is a service which they call Allnight; which is as it were a great cake of wax, with the wick in the midst; whereby it cometh to pass, that the wick fetcheth the nourishment farther off. We see also that lamps last longer, because the vessel is far broader than the breadth of a taper or candle.
373. Take a turreted lamp of tin, made in the form of a square ; the height of the turret being thrice as much as the length of the lower part whereupon the lamp standeth : make only one hole in it, at the end of the return farthest from the turret. Reverse it, and fill it full of oil by that hole;, and then set it upright again ; and put a wick in at the hole, and lighten it: you shall find that it will burn slow, and a long time: which is caused, as was said last before, for that the flame fetcheth the nourishment afar off. You shall find also, that as the oil wasteth and descendeth, so the top of the turret by little and little filleth with air; which is caused by the rarefaction of the oil by the heat. It were worthy the observation, to make a hole in the top of the turret, and to try when the oil is almost consumed, whether the air made of the oil, if you put to it a flame of a candle, in the letting of it forth, will inflame. It were good also to have the lamp made, not of tin, but of glass, that you may see how the vapour or air gathereth by degrees in the top.
374. A Fourth point that importeth the lasting of the flame, is the closeness of the air wherein the flame burneth. We see that if wind bloweth upon a candle, it wasteth apace. We see also it lasteth longer