On various preparations of carmine

On various preparations of carmine

3%2 *‘BE PRANKtlW SOUR&AL ANil guishecl. Tile frames, with the seeds still sticking to the skitiS, are &en dried slowly in the shade, till the se...

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3%2

*‘BE

PRANKtlW

SOUR&AL

ANil

guishecl. Tile frames, with the seeds still sticking to the skitiS, are &en dried slowly in the shade, till the seeds will shake off withou t any violence ; and the skin is left a hard horny substance, with It is then laid on a solid block, co& grain side deeply indented. feretl with wool, and strongly rasped with two or three iron instruments, (the particulai- forms of which need not be. here described,) till the whoie Of’the grain side is shaved, so that the impressions of the The skins are then softened, first seeds are very sli ht and uniform. with water, and t?Ien with a warm alkaline lye, and are heaped, warm and wet, on each other ; by which means, the parts indented by the

imggression+regain much of their elasticity .: nnd hhv@ lost none 01 t/beil*substance by paring, rise up fully to the level of the ehavedpkucess and thus form the promilwzt grains, or the granular texture, peculiar The skin is then salted and dyed. to the shagreen.

The beautiful green dye is giveh, b,y soaking the inner or flesh side Of the skin, with a saturated solution of sal-ammoniac, strewill it over with copper filin 3, rollin, (7it up with the flesh side inwards, am4 pressing each skin wit4 1 a considerable weight3 for about twent -four hours, in which

timq

the sal-ammoniac

dissolves

enough

r copper to of tie

penetrate the skin with a! agreeable sea-green colour. This is rcpeated a second time, to give the colour more bpdy. L&e sftaqreen is dyed with indigo, dissolved in an impure soda, by means of lime and honey. Bluck shagreen is dyed with galls and The skins are finished with oil, or suet. Gtriol.

On various Prepurations

Of

Carmine.

(Continued from y. 302.) CnINESE

CARMINE.

Twenty ounces of very finely-powdered cochineal are boiled witfi B pailful of river water, contained in a proper vessel; to which sixty grains of Roman alum are added. After seven minutes’ ebullition, the boiler is removed from the fire, and the liquor ptit into anothet vessel, by inearls of B siphon : it may also be passed through fioe linen; This liquor is to be preserved for use. A solution of tin is previously prepared, in the following thanher. Ten ounces and a half of com* lnon salt (mtiriate of soda) are dissolved in a pound of aqua-fortis nitric acid :) to this solution, wheh cold, four ounces of Malacca-tid Blings arr? added, by degrees :-a fresh quantity of tin must not be put m till the former is diSsolved. This solutiod is added, drop by drop, to tha heated cochineal liquid ; and the carMine preci itates& When the carmine is deposited, the liquid is decanted ; and t Ke car&nine allowed to dry in the shade, in china or Delft-ware vessels, THE

GERhlhi

METHOD

OF

PREPARlNG

CARMINE.

Six pints of river water are boiled in a copper vessel: two ounces of powdered cochineal arc then thrown into it, and well stirredh After six minutes’ boiling, sixty grains of powdered a:um are th_rawn

AYERICAN

MECEL4NICS' &A~l~E.

388

in, and the whole sutt’ered to boil for three minutes. The vessel ie then removed from the fire ; and the liquor drawn off with a siphon, and iiittbretl through a lawn sieve. The iiquor is then placed in man)china or Delft-ware vesseis, and ailowed to remain at rest for three days ; WIICIIit is decanted, and the deposits dried in the shade. Aftel. tlkrw trrore Claysthe liquor is again to be decanted; when it will have formctl carmine of an inferior cluality. ALYON’S

I’KOCESS.

sotl;~, tiissolved in a of cochincnl ; and,

cshote is afierwardu left at rest fur twenty-five minutes. The liquor, which is then become ofa very fine scarlet coiour, is to be decanted into another vrsscl ; and the whites of two eggs, msiously bcatcn up with half a pout~tl of tvater, are atldrd : the whorc ts . then stirred up with thrs brush ; iclltl the VPSW~ ~phccd upon the fire, and made to boil. ‘I’hc whites of yggs coagulate, and precipitate with the colourinv substance. which iorms the carmine. ‘i’he boiler is then remove s from or thirty minutes, in order tlic fire, atic! left at rest for twenty-five that the carmine may entirely deposit itself. The”liquor is decanted; and thr ticposit placed upon fine linen, that it mny drain. The carmine is nfteln-arcis re~novetl with silver or ivoty spoons, and dried upon plafcs which are covered with white paper. A pound of Go&ine:tl, by this pl’ocess, affords au ounce of carmine. It is essential that sofy wate: only Lwemployed. \Ye see: by two of these reel )es, that alum IS not, as many&hors have advancec!, an intlispensab 1e material, in the preparation of carmine: in one Instance, it is replaced by the acid oxalate of potash; in another, by the I~ydrochloratc of tin : and the experiments of MN. Wlctier and Caveutou prove that these salts, as well as the alum, serve, both to heicrhten the colour, and to assist in its precipitation, by the actiorr of &eir excess of acid OII the animal matter contained in the cochineal. C’armine is very much used in Inin;ature-paintin,rr: and a great quantity pf it is also employed in the manufacture of artificial ilowt:rs. The contrctioners and apothecaries make use of ‘4, to colour various preparations; and it gives a beautiful tint,, when m~erk with any subIF hen it is used as a liquid stances which they wish to colour. coIour, it is dissolved in the volatile alkali: the excess of alkali is dissipated by spontaneous cvaporatiou; aud, when the solution is becuriae

inodorous,

it

is

fit

Vor

use.

MM. Pelleticr and Caventou have given the name of Cartnine to matter contained in the cochineal, which is the the pure cotonri?,- 11‘ basis of the carmine. These chemists have succeeded in sqwmiing it> by first macerating the cochineal in ether, in order to fret it Irum

334

THE FRANKLIN

JOURNAL AND

& greasy

substance which it contains, and then repeatedly treating the At each decoction, It deposits, on cochineal with boiling alcohol. cooling, a granulated matter, of a beautiful.red colour; and, on leaving the solutions to a spontaneous evqoratmn, the deposit continues to form, and then assumes a crystalline appearance. In this state, the colouring-matter of the cochineal is nearly pure; nevertheless, it still retains a little of the greasy substance ; to divest it of which, entirely, MM. Pelletier and Caventou direct it to he re-dissolved in This alcohol at 40°, and then to add to it an equal part of ether. mixture is at first very thick, but afterwards becomes clear ; and, in ;L few days, the sides of the vessel are found to be covered with an incrustaiion of a brilliant reddish-purple colour, which is p2cre cm-This has been characterized bv the following properties: its mine. appearance ; is perfectly colour is a vivid purple ; it has a crvstallized unalterable in the air; heat easily decon~po~es it, and without producing any azote; it is very soluble in water; and neither crystallizes by evaporation or coohng ; it is insoluble in ether; soluble jn boiling alcohol, 8%

It appeared from hf. Dreant’s former experiments, published in the ii 1Julletin de la Societe d’Encoura,oement, ” for 1821, that the watered or wavy appearance dn fhe eastern damasked steel is not mechanically pr0d11~t1, but the result of a particular composition, and he has at Icngtll axcrtained that it is owmg to an increased quantity of carbon incc,rlx,ratc(l with the steel beyond the proportion contamed in the C~~IIJOII sorts. According to this chemist, the effect de )entls on two states of combinatian in which the carbon exists in t\ le steel, and numerous esperimcnts have enabled him to give the rules for several procrsses for the manufacture of different kmds of cast steel. ~‘?‘he watered (moSe) surface of the oriental sabres has led to the supposition that they are made from what is called stu$(etofe,) that is, a bundle of steel bars, or wires, forged and welded together, and twisied in different directions. 6‘A long series of experiments has taught me that the substance of the oriental damask is a fused steel, more loaded with carbon than our European steels, and in which, by means of a proper man?gement in the cooling, a crystallization of two distinct compounds of UOB and carbon is ett’ccted. ‘4 This separation is the essential condition ; for if the fused matter be suddenly cooled, as is the case when cast into small ingots, no appearance of damask is perceptible; it is only to be discovered by uSmv a magnifying lens. 4 ron and carbon form at least three distinct compounds ; steel, a From the .RnnaQ deaMines.