Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/546

STA have the black degenerate into blue, they need only add less of the blue, and a little of the ceruss and agate white before described. They have two peculiar ways of applying the red, beside the common one, both which require a nice workman, and make the ware come very dear. They call the one of these oils red, and the other blown red. Observ. sur les Coutumes de l'Asie. See Blown.

There are many things practifed by the Chinefe in their colouring and forming the feveral kinds of porcelain, which may be well brought into ufe among us, and give a new Value to our own wares, even though we fhouid never ar- rive at their art of making the tiling itfelf. One kind of colouring eaiily introduced among us, would be what they call hoan ton boon. .This produces veflels of great beauty and price, and is dune in this manner. The matter, of which the veflels are made, for this purpofe, need not be fine ; they ufually take any of the common veflels baked, without hav- ing been varn'ifhed, and cenfequently fimply white, and without lu'ftre. When thefe are intended to be of one fimple colour, they need only be plunged into a liquid varnifh or oil, as the workmen there call it, coloured with fuch in- gredients as will ftrike the mod lively tinges : but if it is to be coloured in compartments, as is ufually the cuftom with this fort of China, it is to be done by the pencil. The ufual way is to paint thefe in pannels, one green, another blue, and fo on, and they make a very agreeable appearance. There requires no more to this, than the laying on the colours tolerably thick with a large pencil ; but if the pictures of animals, and plants are to be given, they are to be done with the moil permanent colours, and the VefTel being again well baked, becomes very beautiful. Obferv. fur les Coutumes de l'Alie, p. 320. The Chinefe, who are deceivers in every thing, find the way of cheating very much in regard to this fort of China- ware. They paint the flowers of plants, and fome parts of the birds, t5V. in very bright colours, after the veflel has been baked. Vermilion is a fine colour, which they often add on this occafion ; but they cannot ufe this before the baking, becaufe it would be deftrcyed by the fire. Thefe colours which are laid on afterwards cannot laft, but foon rub off in the, wiping, or ufing the things ; the others laft for ever ; for they are laid on with the greateft heat of all, the vefiels being put into the fame furnaces to lay on thefe, as the other things are baked in for the firft: time. Salt petre, and powder of flints, are generally the things added to the colours thus laid on, to make them penetrate, and run properly. Thus for the fine deep violet colour, which makes the greateft figure of all others on this ware, they mix together equal quantities of the fine azure, the powder of flints and fait petre, all firft powdered feparately till perfectly fine ; this is tempered with water, and then laid on with the pencil, and though it looks rough at firft, it comes out of the furnace of as beautiful a glofly hue as any thing can be conceived. The yellow is made by mixing together three ounces of cerufs, and three ounces of pow- dered flints, and adding three, four, or more drachms of the red copperas, till the whole is of the proper degree of colour. The white is compofed only of powder of, flints and cerufs, with a fmall admixture of the fait petre, or it will fucceed tolerably well without. Thefe are all the particu- lars necefTary to be obferved for the making a fort of por- celain of great beauty, in which the nature of the ware it- felf is not concerned ; fo that it feems cafy to imitate it with any of our own wares.

In the baking of this, or any other kind of coloured China, the fecond time, there is, however, fome caution to be ufed in the placing the pieces. The Chinefe are very artful in their difpofition of thefe, arranging them in the moft compact manner, and putting the little ones within the great ones ; but great care is alfo neceflary, that the veflels do not touch one another in the parts where they are painted, for the confequence of that would be .the fpoiling of both veflels, as the colours would run together. The bottom of one vefTel may generally be placed on the bottom of another, though both are painted, becaufe the rims are not painted, and they keep the painted parts from touching one another, High and narrow veflels, fuch as chocolate-cups, and the like, are very troublefome on this occafion. The method the Chinefe workmen take with them, is this : they place a range of them, fo as to cover the whole bottom of the fur- nace, and they cover this with a thin bed of broken China- ware, over which they place another row of the cups, and fo on to the top, where they lay on no covering : they ne- ver bake any thing elfe with thefe cups, when they are of this kind of twice-baked porcelain. Obfervat. fur les Cou- tumes del'Afie, p. 321. Staining of Jl ones. The art of Jlaining the gems and hard ftones, could it be brought to perfection, would be a very elegant and ufeful one ; but it is loaded with fo many diffi- culties, that many, who have worked largely in the at-, tempt, have given it up as impoflible to be carried to any degree ot perfection. The heat, neceflary to be given to the ftones in the common way of attempting this operation, 1 jpoils the ftone, in order to give it the colour. It is true,

that fomethlng is to be done with folutions of fllvcr, and the other metals, in acid menftrua without fire, and fame- thing may be done with a moderate heat alone:, without the u(e of any thing elfe; but chance has difcovered another way, by which, without heat, it may be done in a very eafy manner. This was difcovered by Mr. Mullcr, who grinding fome aurum fulminans, made by diflblving gold in aqua regia, and precipitating it with fait of tartar, together with fome red glafs powdered, and a little water added, found that this mixture ftained the onyx, or chalcedony, of which the mortar was made. He was rubbing this mix- ture together to make an enamel colour, and leaving it three or four days in this little mortar, he found, that not only where it had been rubbed againft the bottom of the mortar, but where it had accidentally fplafhed againft the fides of it, and on the furface of the peftle*, it had tinged them both very deeply to a fine red, leaving the intermediate parts of a true onyx, or chalcedony colour, wholly unaltered. The polifh of the ftone was not injured in the places where it was thus Jlained, nor could any art get out the colour, though it was tried with alkalis, and other {harp liquors. This colour was not given to thefe parts of the ftone of the mortar in Ample blotches, but formed itfelf into regular lines, as we fee the natural colours of ftones do; but" this not in the fame degree of colour, but fome of the lines were deeper, others paler.

This experiment was repeated in feveral other mortars of the fame ftone, but without fuccefs ; on which the ftones, of which they were compofed, were examined with the help of glafles, and it was found that this mortar chanced to be made of a more flaky chalcedony than any of the others, though it appeared equally folic] and beautiful to the naked eye, and bore a polifh no way inferior to them. It may be worth while, on this occafion, ftrictly to examine ftones of this chalcedony kind, and on meeting with a plate of one of them of this flaky kind, to cover it with this mixture, and by that means give it a feries of lincations, which mult make it a very beautiful and valuable ftone. -The polifh. will not be ' injured by this, or if it fhould, the adding a new polifh will not at all affect the colours. In the fame manner the texture of ftones, intended for any other expe- riments in Jlaining, fhculd be confidered, and the choofing proper ones may make this proceis fucceed on them. Phil. Tranf. N° 179.

STAJOLUS, among the Romans, a measure of length used in surveying land; it was equal to five palms and three fourths of a palm. Pitisc. in voc.

STAKE, the name of a small anvil used by smiths; sometimes it stands on a broad iron foot, on the work-bench, to be moved up and down occasionally; and sometimes it hath a strong iron spike at the bottom, by which it is fixed to some place on the work-bench. Its use is to set small and cold work strait, by hammering it on the stake, or to cut or punch upon with the cold chisel, or cold punch.

of a plough. The stake is an upright piece of wood, passing at its bottom through that link of the tow-chain which passes through the box of the plough, and at its upper end receiving the end of what is called the bridle-chain, which ties it to the crow-staff, or if it be not long enough, a wyth, or cord, is used to tie it; it is also tied to it again, a little below the pillow of the plough, by another wyth or cord, Tull's Husbandry, See the articles, &c.

STAL-boat, a kind of fishing-boat, mentioned 27 Eliz. c. 21. Blount.

STALACTAGNIA, in natural history, the name of a genus of spars. The word is derived from the Greek σταλάσσω, stillatitious, or formed by dropping, and ἁγνός, pure.

The bodies of this genus are formed by the dropping of water from the roofs of subterranean caverns, and are the purer sort of what are called by authors stalactitæ. They are crystalline sparry bodies, formed into oblong conical figures, composed of various crusts, and usually found in form of icicles. Of this genus there are three known species. 1. A hard and white one. This is a very beautiful body, and is found in many parts of England, as well as other countries. 2. A white shattery one, found in the same places. And 3. a yellow shattery one, common with us in Yorkshire, Devonshire, and Derbyshire; as also in many other parts of the world. Hill's Hist. of Foss. p. 363.

STALACTOCIBDELA, in natural history, the name of a genus of spars. The word is derived from the Greek σταλάσσω, ftillatitious, or formed by the dropping of water, and κιβδηλα impure.

The bodies of this genus are formed by the dropping of water from the roofs of subterranean caverns, and are the coarser kinds of what authors have called stalactitæ. They are crystallino-terrene spars, formed into oblong bodies, and found hanging from the roofs of caverns and grottos.

Of this genus there are only two known fpecies. 1. A brownish friable one, common in our subterranean caverns, and even on the insides of new-built stone arches, as those of the New Bridge at Westminster. And 2. a snow-white friable one, found in subterranean caverns in England and Rh