Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/379

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, take root well the firft year, but if fufFered to remain on the ftock longer, they grow woody, and often fail. But the beft method of obtaining vigorous plants, is, by lay- ing down the fhoots ; this is to be done in autumn, and by the autumn following they will have taken root fo well, that they may be taken off from the old plant, and removed to the places where they are to remain. Thefe may be tranfplanted any time from October to April, but the earlier the better.

Rofes, in general, delight in a rich moiff, foil, and an open fituation, in which they will produce great quantity of flow- ers, and thofe much more beautiful than when they are on a dry foil and fliady fituation.

All the pruning they require is to have their dead wood cut, and their fuckers taken away every autumn ; and if there are any very luxuriant branches they may be iliortened, and the doing this will fupply the other parts of the tree with frefh wood. Miller's Gardners DidT:. EJenee of Roses. There is fcarce a more valuable perfume in the world than the eflence of damafk rofes, and fcarce any thing is obtained from its fubje£t with more difficulty and in lefs quan- tity. All elTences or eflential oils arc, while in the plant, con- tained in certain vcncles, lodged in different parts, and of different ftructure ; thefe veficles are in the rofe particu- larly fmall and tender, and are placed very fuperficially ; the confequence of this is, that there is originally but a very lit- tle of this eflence in the flower, and this is the very fubjedt that will be diffipated and loft when the flowers are gathered and thrown in a heap together, as they are fucculent, and very quickly heat in lying together. To avoid all diflipation and wafte of this choice eflence, the rofes fhould be thrown into the ftill as foon as gathered, arid diftilled with very little water, and that in a balneum maris; j then the fire is to be conti- nued fo long as the flowers float feparate about in the water ; but as foon as ever they form themfelves into a cake, and ftick to the bottom, the diftillation fhould be finiihed, as they then yield no more eflence. With all thefe precautions, however, it is with great difficultly we can procure any ef- fence of rofes. What we obtain by this diftillation being chiefly a very odoriferous and fragrant water. In the warmer countries the fame caution affords a larger quantity of oil, •which may be fcparated and preferved under the name of the eflence. In Italy they make fome quantity of it, but there it is very dear ; a vaft quantity of the flowers yielding only a very little eflence, and that being thick and troublefome in the procuring, as it every where flicks to the veflels. It is to be obferved, that the feafon of the year, as to wet or dry, makes a very great difference in the eflential oils of all plants ; they are always much finer in dry and hot feafons than in cold and mo'ifl : we find our rofe water in England much finer, and more fragrant, though diftilled in the fame proportion in hot and dry fummers than in colder and rainy ones ; and Mr. GeofTroy gives an account that he fucceeded, one very hot and dry year, in the making eflence of rofes in France, in the following manner.

As the rofes were brought to him frefh gathered, he turned them immediately into the frill ; and drawing over the water into a glafs matrafs, when it had flood by fome time, and was perfectly cold, he difcovered fome of the eflence fixed to the fides of the matrafs, and the furfacc of the water co- vered with a thin reticular pellicle. All the contents of the matrafs were put to filter through a paper, fupported by a fine Iinnen cloth ; and the filtrated water was added to new rofes for many fucceeding diftillations, the produce of which was all filtered through the fame paper. After a long courfe of diftillations, with frefh flowers every time, but flill with the fame, veflels and the fame water, there was found in the paper of the filtre a quantity of thick eflence ; this being carefully waihed out of the paper with a fmall quantity of the moil fragrant of the water, and afterwards feparated pure from its furface was very white, and extremely fra- grant, and as thick as fine butter. This is not the only eflential oil which naturally concretes into this nrmffatej oil of annifeed, though fluid, when diftilled, always concretes in the fame manner on the firft approach of cold ; and another oil of this kind is that of the laurel, which is ufed in fome places, though very improperly, to give the fcent and tafte of bitter almonds, or apricot kernels, to foods of different kinds.

Monfieur Homberg has taught us how to gain a larger quantity of the eflential oil of rofes than is ufual in di- ftillation, by the previous addition of mineral acids, as the fpirit of fait, vitriol, c?Y. thereto ; which increafe the fermentation, and joining with the oil render it more liquid, and eafier to be raifed by heat. He advifed a perfumer, who before fcarce obtained an ounce of oil from an hundred weight of rofes, to fieep his flowers for fifteen days water made fharp with fpirit of vitriol, by which means the perfumer, upon diftillation, found his quantity of oil increafed almoft a third.

The_ perfumers keep the ftru&ure of the veflel they em ploy in this diftillation in great fecret. Mr. Homberg tell. us, it is a large convenient flill, that opens th a tube at the top to receive the water which muft often be poured Suppl. Vol. II.

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upon the rofes to bring over the oil with it ; this it does but very flowly, and fo requires that its quantity be We - the frill alfo opens below, that the flowers, when they will yield no more oil, may be eafily taken out ; but the prin- cipal contrivance is the figure of the vefTel which receives the oil; this is made like an ordinary matrafs, from the lower part of the belly whereof comes a tube, as from an old fafhioned cruet, and riflng to the bottom of the neck of the receiver, it bends outwards j fo that though the vef- fel ufually contains but two or three French pints, it con- veniently receives and lets pafs many hundred pints of the rofe water, without any neceflity of being changed j for a change would lofe the fmall quantity of the oil obtained. The water diftilled runs through a pipe into a fecond re- ceiver : the oil being lighter than the water, floats upon its furface, and adheres to the neck of the veflel as high as the aperture of the little pipe, while the water runs from the bottom of the firft receiver into the fecond. See Mem. de l'Acad. des Sciences, 1700.

Mr. Homberg obferves that this ftill may be ufeful to draw off any kind of precious eflential oils. Rose fly, in natural hiftory, the name given by authors to a peculiar fpecies of fly found very frequently on rofe bufhes, and produced out of a baftard caterpillar, which feeds on the leaves of that tree.

The male of tins fly has a long body, the female a flibrt and thick one ; fhe depofits her eggs in fmall holes, which fhe makes in the bark of the young branches, and for this pur- pofe is furnifhed with a very remarkable inftrument placed at the hinder part of the body, which is a kind of faw. This is a four winged/j, and is fo common on rofe bufhes, that it is fcarce pofltble to mifs it in any of the fummer months ; and the parts of the branches where it has depoflted its eggs, are fo vitiated by it, that they alfo are eafily known. They are ufually fwelled to a greater bignefsj than either the part above or below them, and are ufually fomewhat bent ; they are often black on the underfide, and among this blacknefs the holes made for the eggs, and often the eggs in them may be feen. The head and breaft of this fly are black. Its wings alfo are edged with black, its body is yellow, and its legs yellow, with a few black fpots. If thefe flies be obferved in a fummer morning-, as they are crawling upon the branches of the rofe tree, they will foon be found at work for the depofiting of their eggs. Thefe creatures give us a very good opportunity of obferving the manner in which they perform this, as they are of a very fluggifh difpofition, and will ftand ftill even to be taken be- tween the fingers ; fo that when one of them is in a proper fituation, it may be examined, by bringing the eye near it, and by ufing the common magnifying glafles, without quitting its place or its work ; and if there be leaves of the tree, or fmall branches of it in the Way, they may be removed without difturbing the creature. Reau?nur\ Hift, Inf. Vol. 9. p. 145.

As foon as t\\cfly has found a proper place for her eggs, fhe directs the hinder part of her body downwards, and open- ing a pair of fcaly fubftances placed near her tail, fhe thrufts out from between them an inftrument exactly reprefenting two common faws, with fharp teeth and fmooth backs ; when fhe has fo placed thefe, that their points touch the bark, fhe prefles down her body in order to force the points to enter, and afterwards continues this preflure till the whole length of both faws is immerfed in the wood. If the whole be nearly examined, however, it will be found that a Am- ple preflure is not all the means employed to force them in ; but that as foon as ever the points are entered the bark, the two faws begin to work by means of tendons and muf- cles made for that purpofe, and are moved about exactly as the common faw in the hand of a carpenter ; only that as there are two of them, they always move the contrary way, one being forced in while the other is drawn out ; by this means they become a fupport to one another. As thefe inftruments are extremely fmall, they would not naturally cut an opening large enough for the receiving and covering the egg which is to be depoiitcd there. The crea- ture therefore ufes great art and addrefs in the working with them. She opens the branch, not by making a bare punc- ture, but in the fame manner in which a furgeon opens a vein, by plunging the point of his lancet perpendicularly in, and then raifing it out obliquely; and, in order to enlarge the width of the wound, fhe makes the teeth of each of the faws work forcibly againft the fides o( it at every return. When the aperture is thus made of a proper fize, the creature immediately draws out the faw, and prefling her body down upon the bark, depofits an egg in the hole ; im- mediately after which, fhe covers the orifice with a vifcous fluid, which bubbles up in the manner of foap fuds, and ferves at once to preferve the egg, and to prevent the wound- ed fibres of the tree from decaying too foon. lb. p. 150. When the laying of one egg is thus Sniffled, the crea- ture moves a little way forward or backward on the branch, and then begins the like operation for another egg, and goe* on in this manner till fhe has laid her whole ftore. If the branch be all the Wav proper to receive them, fhe lays K k k them