112

COCOA.

.eather bag, first, with sulphate of baryta in fine powder, afterwards with bone or ivoryblack, to give it the appearance of negra cochineal, and then dried. By this means about12 per cent, of the-worthless heavy spar is sold at the price of cochineal, to the enrich-ment of the sophisticators, and the disgrace and injury of British trade and manufac-tures.

The specific gravity of genuine cochineal is T25; that of the cochineal loaded withthe barytic sulphate 1*35. It was taken in oil of turpentine and reduced to water asunity, because the waxy fat of the insects prevents the intimate contact of the latterliquid with them, and the ready expulsion of airffrom their wrinkled surface. They arenot at all acted upon by the oil, but are rapidly altered by water, especially when theyhave been gummed and barytified.

The quantities of cochineal imported into the United Kingdom in the following yearswere : —

1827. 1828. 1829. 1830. 1831. 1832. 1833. 1834. 1835.

Lbs. 320,722 .258,032 288,456 316,589 244,371 388,478 359,381 410,387 418,320

The quantities re-exported were: —

145,756 158,109 153,738 100,059 168,329 138,270 130,732 265,490 352,023

Humboldt states that so long ago as the year 1736, there was imported into Europe from South America cochineal to the value of 15 millions of francs. Its high price hadfor a long time induced dyers to look out for cheaper substitutes in dyeing red, and sincescience has introduced so many improvements in tinctorial processes, both madder andlac have been made to supersede cochineal to a very great extent. Its price has, in con-sequence of this substitution, as well as from more successful modes of cultivation, fallenvery greatly of late years. At present it is only 7.s. per lb. in London . See ScarletDyeing.

COCOA, STEARINE, and ELAINE. Mr. Soames obtained a patent in September,1829, for making these useful articles, by the following process : —

He takes the substance called cocoa-nut oil, in the state oflard, in which it is importedinto this country, and submits it to a strong hydraulic pressure, having made it up in smallpackages, 3 or 4 inches wide, 2 feet.long, and 1 or 1J inches thick. These packages areformed by first wrapping up the said substance in a strong linen cloth, of close texture,and then in an outward wrapper of strong sail cloth. The packages are to be placed sideby side, in single rows, between the plates of the press, allowing a small space betweenthe packages for the escape of the elaine.

The temperature at which the pressure is begun, should be from about 50 to 55 degrees? .or in summer as nearly at this pitch as can be obtained, and the packages of the saidsubstance intended for pressure, should be exposed for several hours previously to aboutthe same temperature. When the packages will no longer yield their oil or elaine freelyat this temperature, it is to be gradually raised; but it must at no time exceed 65 degrees?and the lower the temperature at which the separation can be effected, the better will bethe quality of the oil expressed.

When the packages are sufficiently pressed, that is, when they will give out no moreoil, or yield it only in drops at long intervals, the residuum in them is to be taken out andcleansed and purified, which is done by melting it in a well-tinned copper vessel, whj c ^is fixed in an outer vessel, having a vacant space between, closed at the top, into whichsteam is admitted, and the heat is kept up moderately for a sufficient time to allow theimpurities to subside; but if a still higher degree of purity is required, it is necessary t°pass it through filters of thick flannel lined with blotting paper. . .

Having been thus cleansed or purified, it is fit for the manufacture of candles, whicare made by the ordinary process used in making mould tallow candles. Having thudisposed of the stearine, or what is called the first product, he proceeds with the ela* 1 ’or oil expressed from it, and which he calls the second product, as follows: that issay, he purifies it by an admixture, according to the degree of its apparent foulness? ^from 1 to 2 per cent, by weight of the sulphuric acid of commerce, of about 1*80 s P eCl t i vgravity, diluted with six times its weight of water. The whole is then to be violentlyagitated by mechunical means, and lie prefers for this purpose the use of a vessel ccmstructed on the principle of a common barrel churn. When sufficiently agitated, A 'T 1 .have a dirty whitish appearance, and is then to be d awn off into another vessel, in y iC ait is to be allowed to settle, and any scum that rises is to be carefully taken off- _day or two the impurities will be deposited at Ab e bottom of the oil, which willcome dear, or nearly so, and it is to be filtereiihrough a thick woollen cloth, after wit will be fit for burning in ordinary lamps and for other uses. r re ..

The process of separating the elaine from the stearine, by pressure, in manner a ^said, had never before been applied to the substance called cocoa-nut oil, and conseque ^no product had heretofore been obtained thereby from that substance, fit for ^ e ? n “ usua lnufuctured into candles in the ordinary way, or for being refined by any of the