C O L D. 



gold and the liydrojrpn of the ammonia combining to form 

 water, and to the hboration of the azot and its fudden af- 

 fum-rtion of the gafeous llate.'" Aikin's Dift. 



Gold, Leaf, or heuUn ^ohU is gold beaten w ith a ham- 

 mer into exceedingly thin leaves. It is aftoiiifliing to con- 

 hd?r the iinenefs to 'which a body of gold is thus reduced. 

 In an experiment of Reaumur's, forty-two fquare inches 

 and three tenths of gold-leaf weighed one grain Troy ; and 

 Mr. Boyle found tlint fifty and feven tenths weighed but 

 a grain.' As ;\ cubic inch of gold weighs 4902 grains, 

 the thicknefs of the gold-leaf examined by the one was 

 the 207355lh, and of that by the other only the 248532nd 

 part of an incli. See Ductility of Gold. 



This gold is b.'at on a fmooth block of black marble, 

 from two hundred to fix hundred pounds in weight, and 

 about nine inches fquare on the upper furface, litted into 

 the middle of a wooden frame, about two feet fquare, fo 

 as that the furface of the marble and frame form one even 

 plane. Three of the fides are furniflied with a hjgh ledge, 

 and the front, which is open, has a leather flap fallened to 

 it, which the gold beater ufes as an apron, for preferving 

 the fragments of gold that fall off. Three hausmers are 

 employed in this bufinefs, having two round and iome- 

 wh.it convex faces : t!ie firft, called the cutch hammer, is 

 about four inches in diameter, and weighs fifteen or iixteen 

 -pounds : the fecond, called the flioderlng hammer, weighs 

 about twelve pounds, and is about the fame diameter : the 

 third, called the gold or finidiing hammer, weighs ten 

 or eleven pounds, and is nearly of the fame width. The 

 French ufe four hammers, differing both in (ize and fliape 

 from thofe of our workmen. 



The gold beaters alio ufe three kinds of animal mem- 

 branes ; fome of which are laid between the leaves to pre- 

 vent their uniting together, and others over them to defend 

 them from injury by tlie aftion of the hammer. For the 

 oatfide cover, they ufe common parchment made of (heep 

 ikin ; for interlaying with the gold, firit, the fmoothefl and 

 clofeft vellum made of calves ikin; and afterv.-ards, the 

 much finer ikins of ox-gut, ftript off from the large flraight 

 gut flit open, prepared on purpofe for this ufe, and^ hence 

 ■c-^t&. gold-lniter s Jh'm. The general procefs of their pre- 

 paration, is faid to confifl in applying one upon another, by 

 .the fmooth fides, in a moill ftate, in which they readily 

 cohere and unite infeparably, ftretching them on a frame, 

 and carefully fcraping off the fat and rough matter, fo as 

 to leave only the fine exterior membrane of the gut ; beat- 

 in'f them between double leaves of paper, to force out the 

 remaining umSluofity ; moiftening them once or twice with 

 an i-Ti'ufion of warm fpices, and laftly, drying and prefTing 

 tl em. It is faid, that fome calcined gypfum, or plafter 

 of Paris, is rubbid with a liare's foot, both on the vellum, 

 and ox-gut ikins, which fill up their pores, and prevent 

 the gold'lcaf from flicking. Thefe f]<ins, after feventy or 

 t'ighty repetitions, become unfit for ufe; but their virtue 

 may be reilored by interlaying them with leaves of paper 

 r.ioitlened with vinegar or white wine, beating them for a 

 whole day, and afterwards rubbing them over with plaller 

 of Paris ; and even holes in them may be repaired by the 

 dextrous application of frefh flcins. 



Gold, the manner of preparing and beating. They firft 

 melt a quantity of the pureil gold in a black-lead crucible, 

 with fome borax, in a wind furnace, and pour it into an 

 iron ingot mould, fix or eight inches long, and \ of an inch 

 wide, previoufly greafed and heated ; the bar of gold is 

 made red-hot and forged on an anvil into a long plate, 

 which is farther extended, by being pafTed repeatedly be- 

 tween polifli'-d Heel rollers, till it becomes a ribband, as 



thin as paper. This ribband is divided by compafTcs, ancl 

 cut with (hears into equal pieces, which are forged on an 

 anvil till they are an inch fquare, and afterwards well an- 

 nealed. Two ounces of gold, which is the quantity melt- 

 ed at a time, make a hundred and fifty of tliefe fquares, 

 fo that each of them weighs fix grains and two fiftlis ; 

 and as 4902 gi-ains of gohf make a cubic inch, the thick- 

 nefs of the fquare pieces is about the 766th part of an 

 inch. All thefe fquares are interlaid with leaves or vel- 

 lum, three or four inches fquare ; one leaf being laid be- 

 tween every two of them, and about twenty more of the 

 leaves are laid on the outfides : over thefe is drawn a 

 parchment cafe open at both ends, and over this another, 

 in a contrary direftion, fo that the veilum and gold leaves 

 are kept tight and clofe. The whole is then beaten with 

 the heavielt hammer, till the gold is llretched to tlie ex- 

 tent of the vellum : the pieces taken out of this cafe or 

 mould, are cut in four with a fteel knife; and the fix 

 hundred pieces thus produced are interlaid, in the fame 

 manner, with pieces of the ox-gut fiiius, five inches 

 fquare. The beating is repeated with a lighter hammer, 

 till the golden plates have acquired the extent of tSie fkin ; 

 when they are divided into four, by a piece of cane cut 

 to an edge. The whole number of leaves is then divided 

 into four parcels, which are interlaid, as before, and 

 beaten feparately, till they are ftretched for the third time 

 to the fi/e of the fltins. The French repeat the divifion 

 and beating once more. After the laft beating, the leaves 

 are taken up by the end of a cane inllrument, and being 

 thrown flat on a leathern cufliion, are cut to a fizc, one 

 by one, with a fquare franie of cane made of a proper 

 fliarpnefs, or with a frame of wood edged \\'ith cajie. They 

 are then fitted into books of twenlv-five leaves each, the 

 paper of which is v.-ell fmoothed, and rubbed with red bole 

 to prevent their flicking to it. The fize of the French gold 

 leaves is from fomewhat lefs than three inches to 3^ fquare : 

 that of oui 's from three inches to 3 i. We Ihall here obferve, 

 that the gold ufed for the above purpofe is never pure, 

 becaufe pure gold is too duttile to be worked between the 

 gold-beater's Ikins. The newefl flcins will work the finefl gold, 

 and make the thinned leaf, becaufe they are the fmootheil. Old 

 fl<ins, being rough or foul, require coarfer gold. The 

 finefl: gold for tliis purpofe has three grains of alloy in the 

 ounce, and the coarfeft 12 grains. In general the alloy is 

 fix grains, or one eightieth part. The alloy of kaf-gohl 

 is filver, or copper, or both, and the colour is produced 

 of various tints accordingly. Two ounces and two peiniy- 

 weights of gold are delivered by the mailer to the work- 

 man, who, if very ikilful, returns 2000 leaves, or So books, 

 of gold, together with one ounce and .fix pennyweights 

 of walle cuttings. Hence one book weighs 4.8 grains ; 

 and as the leaves meafure.3.3 inches in the fide, the thick- 

 nefs of the leaf is one two hundred and eighty-two thou- 

 fandth part of an inch. 



The French prepare what is called green gold-leaf, from 

 a compofition of one part of copper and two of filver, 

 with eighty of gold; but Dr. Lewis obferves, that fueh 

 an admixture gives no greennefs to gold, and that this kind 

 of leaf is made from the fame fine gold as the highcft 

 gold-coloured fort, the greeuilh hue being a fup<'rficial teint 

 given to the gold in fome part of the procefs : this leaf 

 is chiefly ufed for the gilding of books. A kind of leaf, 

 called parly-gdd, is form.ed by laying a thick leaf of filver, 

 and a thiimer one of gold, flat on one another ; they arc- 

 then heated and prefTed together, fo as to unite and cohere ; 

 and being beaten into fine leaves, as in the foregoing 

 procefs, tlie gold, though only in quantity a fourth 



of 



