Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/670

 T R A

T R A

The fourth clafs is diftinguifhed by the phrafe nympha vermi- formis ; and the creatures of this clafs remain always Ihut up tn the cafe of the worm or maggot, without any poffibility of difccrning the parts, till rafting both fkins at once, it becomes a perfect and free animal, capable of propagating its fpecies. Thofe infers which come forth perfect, and in their own proper form, out of the esg, fuffer no future changes, but only the cafting off their fkins ; but thofe which come forth under the envclopement of a vermicular coat, do, befide caft- ing their fkins, after a proper time of eating and crawling about in that ftate, become nymphas j and that all infects, as well thofe which come out of the egg in the worm ftate, as thofe which come forth in their own form, are originally, in the egg, all in the nymph-form ; and that thofe which come out of the egg perfect animals, have no other difference in the manner of their productions, from the others, but that they have fuffered in the egg, and out of the way of our infpedf ion, all thofe changes which the others do undergo in the chryfalis or nymph-ftate, in our fight. The parts of the nympbze of thefe animals protuberate and expand themfelves by degrees, much in the fame manner that the buds of flowers of plants do ; and the caterpillar is certainly the butterfly itfelf, only co- vered with a mantle which hides itsfcveral limbs from our eyes till thrown off.

Thus are the general tribes of infects regularly reduced to thefe four clafTes, in regard to the manner of their production, Thofe particular fpecies which feem not reducible to thefe, or any other rules, or for which farther obfervation at leaft is re- quired, are the glow-worm, the fcolopendra, the julus, the weavil or cuiculio, the dung-beetle c?r pilularius fcarabieus, the fmalleft water-beetle, and the fcorpion. See thefe under their feveral heads. Swam. Hift. Infects.

TRANSFUGA, in antiquity, adefcrter. Among the Romans, deferters were commonly punifhed by cutting off their hands, it being thought, that living in fuch a miferable truncated condition, would ftrike. more terror than death itfelf. We find, however, ithat deferters were likewife crucified, burnt alive, thrown from the Tarpeian rock, or expofed to wild beafts at public fhews. Pitift. m voc -

TRANSMUTATION (Cycl.)— Transmutation of Me- tals. Among the many things urged in favour of the belief of the poffibility of this effect of chemiftry, the experiment of Thurneiffer, who, in the prefence of the Great Duke of Tufcany, converted one half of a common iron nail into gold, by only dipping it, while hot, into a certain liquor, has given great encouragement to the fearchcrs after that famous f,cret. The nail is ftill preferred in, the repository of the Great Duke of Tufcany at Florence ; and we have, in a very famous Englifh collection, the blade of a knife, half iron and half gold, faid to have been effected in the fame manner, and pur- chafed by the prefent poffelfor at a very ccnfiderable price. Tachenius, however, has difcovered the cheat of the Floren- tine nail ; ant! probably the matter does not ft and much better, on examination, with the Englifh knife. This author gives a procefs by which iron may be fo prepared as to be made to mix perfectly with gold. This was the whole fecret of Thur- neiffer, who in this manner made his nail half iron and half gold, and then coating it all over with a ferrugineous matter, made it appear all iron. When this had been, in this Mate, fubjedtcd to the examination of the prince, and a great many other perfons, he heated.it red hot, and by that means burnt off the ferrugineous part of the golden end ; and then dipping it into a certain oil, which he pretended to have great efficacy, the gold appeared, and was pretended to have been made by the oil from the iron. Tachenn Hippocrat. Chem. Mr. Boyle thinks there is no impoffibility in the nature of the thing, that one metal fhould be tranfmutcd into another : And in confirmation of this opinion, he mentions %.tranfmu- tation of gold into filver, by means of his menjiruum peracu- tum. Monfieur Homberg declares, he has changed filver into gold by heat \ Mr. Boyle alfo mentions an anti-elixir, which, in very fmall proportion, would confiderably debafe gold b in many refpects, and particularly by reducing its fpeci- fic quantity from 19 to 15 * times that of water. — ['Mem. Acad. Scienc. Anno 1709. b Works abr. vol. 1. p. 78.]

Transmutation of Colours. The change of colour of a decoction of the nephritic wood, according to the different lights it was viewed in, long perplexed the wits of thofe who attempted to account for it ; but Wolfius has carried the ex- periments on this decoction much further, and found a way of giving it its colours again, after taking them wholly away. If this decoction be held between the eye and the light, it appears of a blue colour ; but if the eye be placed between it and the light, it appears then of a yellowifh or a reddifh co- lour. If a few drops of oil of vitriol be dropped into it, it will appear of a gold yellow in whatever light it is viewed ; but if too much of this oil be added, the whole becomes foul and obfeure ; and if a few drops do not produce the effect, it is a fign that the decoction is too ft rong, and that it muft be diluted with water.

Oil of vitriol has the fame effect upon many other decoctions of the woods, particularly on that of Brafil wood, which is of a fine red, but immediately becomes yellow on dropping a fmall quantity of this acid into it. And, as in the other in- 1

fiance, fo in this, It is neceffary to the fuccefs of the experi- ment, that the tiniture be not over ftrong. A few drops of oil of tartar added to this yellow liquor turn it red again, as at firft ; and if more oil of tartar be added, the colour becomes bluifh, with a tinge of red, much ftronger than the colour of the nephritic wood at firft, when held between the eye and the light. In all experiments of this kind, the weaknefs of the tincture produces the greateft beauty ; and therefore it is beft, inftead of making a decoction, to make only a cold in- fufion, by putting a fmall quantity of the chips of the wood into water, and letting this ftand cold for fome time. Act. Erudit. Ann. 1718. p. 321.

A tincture of red rofes, made with common water and oil of vitriol, is well known to be of a very beautiful red colour ; yet when the water has flood ever fo long on the rofes alone, it has fcarce any colour : If it be ftrained off in this colourlefs ftate, and the oil of vitriol then added, the red colour is pro- duced as ftrongly as if this acid had been dropped into the water while the rofes were yet in it. When the liquor is of this fine red colour, a fmall quantity of oil of tartar makes it immediately green ; and if more oil of vitriol be added to this green liquor, it becomes red again, but is muddy, and not fo well coloured as before. If a few drops of a- folution of corro- five fublimate be added to this, it docs not at all change co- lour j and on adding more water, with lalt of tartar diflblved in it, the liquor became red again, but of a very different red from what it was before in its muddy ftate, bang now clear and deeper. When the tincture of roles has fcarce any colour, a fmall quantity of fait of tartar makes it green, but a large quantity makes it yellow. A few drops of oil of vitriol added to this yellow liquor, turned it to a pale red, and this could never be made green again by oil of tartar. Alum- water, ad- ded to a folution of fait of tartar, makes a white and opake fluid, though they are both feparately pellucid. What is moft obfervable in thefe experiments on the infufion of woods, is, that oil of tartar, and a folution of fait of tartar in water, have a very different effect. Thus an infufion of Brafil wood is red; and on dropping to it a few drops of oil of vitriol, it becomes yellow. If oil of tartar be added to this liquor, it only makes it yet more yellow; but if a folution of fait of tartar in water be added to this, it makes it red again. Act. Erudit. Ann. 1718. p. 322. TRANSPIRATION {Cycl.)— Transpiration of Plants. It is evident that plants as well as animals continually fuffer a Iofs of their fubftance and juices, and that in two manners ; by a fenfible Tranfpiration^ and by an infenfible one. The latter of thefe is perceived very plainly in obferving, that in the heat of fummer, toward the clofe of the day, thofe plants which in the morning were very lively and vigorous, and in a perfectly good ftate, are then found feeble, and, as it were, withering, and bending down toward the earth. It is with thefe plants juft as it is with men and other animals, who are in the fame manner faint and languid, by reafon of their great Tranfpiration during the heat of the day. The fenfible Tranfpiration of plants is lefs eafily proved than this infenfible one, which feems fomewhat ftrange. By fenfi- ble Tranfpiration in a plant we underftand an evacuation made by means of the pores of the leaves of a fubftance too thick and coarfe to be evaporated as foon as difeharged, as the mat- ter of the infenfible Tranfpiration is. This matter is, how- ever, not unfrequently found on the leaves of trees, though it is there ufually miftaken for the remains of dew fallen upon them.

This, however, is not the cafe, as may be eafily determined by the following confiderations : 1. That the fluid matter upon the leaves of thefe trees is not merely aqueous, but is vilcid and glutinous, and fweet to the tafte. 2. That it is always found in greater quantity on thofe leaves which are ex- pofed to the fun, than on thofe which are {haded. 3. The leaves which abound in this appear lucid and gloffy in feveral places, thefe lucid parts fometimes appearing only in form of fpots, and fometimes in fmall fpaccs of a twelfth of an inch long ; and fometimes leaves are found with their whole upper furface covered with one continued coat of it. 4. There is no appearance of this matter upon the leaves, either in the night, or before fun-rife in the morning ; the occafion of which is, that it is only drawn out by the heat of the fun; and being in itfelf of the nature of manna, that is, being fo~ luble in aqueous menftruums, it is carried off and diflblved by the dews which fall in that time. 5. The bees are often found collecting this matter from the leaves of trees, as care- fully, and loading themfelves with it in the fame manner, in order to make honey, as they do the fweet fubftances from the bafes of flowers. This matter is the fame with that in flowers, both are extravafated in the fame manner, and both are collected by the bee without injury to the plant. Since honey, therefore, is the matter of the fenfible Tranfpiration of plants, it cannot be wonderful that it fhould fometimes have the flavour of that plant whofe juices it once was a part of, or that the Narbonne honey fhould have the flavour of rofemary ; and fo of others.

The trees which yield this fenfible Tranfpiration in the moft obvious manner, are the feveral fpecies of maple and of lime. It is found more or lefs on a vaft number of others ; and many

plants,