COCHINEAL.

309

fine; M C, middling; 0 C, ordinary. A melting furnace, containing 8 pots of glass,produces in' 24 hours, from 24 cwts. of the mixture, 19 cwts. of blue glass; and from$ to | cwt. of scoriae or speiss (speise). The composition speise, according to Berthier,is nickel, 49-0; arsenic, 37-8; sulphur, 7-8 ; copper, 1-6; cobalt, 3-2 in 100. Nickel,arsenic, and sulphur, are its essential constituents; the rest are accidental, and oftenabsent. The freer the cobalt ore is from foreign metals, the finer is the color, and thedeeper is the shade; paler tints are easily obtained by dilution with more glass. ThePresence of nickel gives a violet tone.

The production of smalt in the Prussian states amounted, in 1830, to 7452J cwts.;and in Saxony to 9697 cwts.; in 1825, to 12,310 cwts.

One process for making line smalt has been given under the title Azure ; I shall in-troduce another somewhat different here.

The ore of cobalt is to be reduced to very fine powder, and then roasted with muchrare. One part, by weight, is next to be introduced, in successive small portions, intoan iron vessel, in which three parts of acid sulphate of potassa have been previously*nsed, at a moderate temperature. The mixture, at first fluid, soon becomes thick anddrrn, when the fire is to be increased, until the mass is in perfect fusion, and allwhite vapors have ceased. It is then to be taken out of the crucible with an irona dle, the crucible is to be recharged with acid sulphate of potash, and the operatione °ntinued as before, until the vessel is useless. The fused mass contains sulphate ofa °balt, neutral sulphate of potassa, and arseniate of iron, with a little cobalt. It is to0e Pulverized, and boiled in an iron vessel, with water, as long as the powder continues£ ou Sh to the touch. The white, or yellowish white residue, may be allowed to separaterom the solution, either by deposition or filtration. Carbonate of potassa, free from^‘na, i s tj len t0 j, e added to the solution, and the carbonate of cobalt thrown down is“f se I>arated and well washed, if possible, with warm water; the same water may bej s se< * 1:0 wash other portions of the fused mass. The filtered liquid which first passess . a ftturated solution of sulphate of potassa: being evaporated to dryness in an iron ves-sul’ h * ay be reconverted into acid sulphate by fusing it with one half its weight ofPhurie acid: this salt is then as useful as at first.

Sent B ox ^ e cobalt thus obtained contains no nickel; so little oxyde of iron is pre-j, > that infusion of galls does not show its presence; it may contain a little copper, ifsu j me tal exists in the ore, but it is easily separated by the known methods. Sometimesfits I hydrogen will produce a yellow brown precipitate in the solution of the

h;- * mass; this, however, contains no arsenic, but is either sulphuret of antimony or

\Th ’ or a mixture of bolh -

“ as been found advantageous to add to the fused mass sulphate of iron, calcined toar Se - ss> an< l one tenth of nitre when the residue is arseniate of iron, and contains nothe „ l ? te cobalt. There is then no occasion to act upon the residue a second time fore T aaba lt in it.

c or * 6 P roce ss is founded on the circumstances that the sulphate of cobalt is not de-al! j,p j hy a red heat, and that the arseniates of iron and cobalt are insoluble inof acid b 4uids. It is quite evident, that, to obtain a perfect result, the excessa PPlied U1 lbe h'sn'phntc of potassa must be completely driven off by the red heat

Wer eret^ ' bs - smalts were imported into the United Kingdom in 1835, and 96,949In iB*> ain ®^ *" or home consumption. In 1834, only 16,223 lbs. were retained,retained ,c^'>o62 lbs. of zaffres were imported, and 336,824 are stated to have beenCOCCTTt is odiously an error. 284,000 lbs. were retained in 1834.f.W^smmcvs; or Indian berry, is the fruit of the Menispermum Cocculus ,k^ckish fee i grows upon the coasts of Malabar, Ceylon, &c. The fruit is

l he ve^et a s * 2e a ^ ar ? e P ea * ^ owes its narcotic and poisonous qualities to

chemical principle called picrotoxia , of which it contains about onea *Ul it i 3 • w cight. It is sometimes thrown into waters to intoxicate or kill fishes;

use fo r Ji,* aave been employed to increase the inebriating qualities of ale or beer,the brewer »* S i* > !c? ,ose * s Prohibited by act of parliament, under a penalty of 200/. uponU ^ 0n the seller of the drug.

v utiou s of Le W J h Vas taken in Europe at first for a seed, but was proved by the obser-° r coccu^ dUcov** a ^ to an insect > being the female of that species of shield-louse,*’here the animal P* 1 ^ ex * co > so long ago as 1518. It is brought to us from Mexico ,

at>e gathered_the !*n S u P° n the cactus opuntia or nopal. Two sorts of cochineal

the cultivated or th *" rom wo °ds> called by the Spanish name grana silvestra;^^ince. The first ■ 8 rana f lna , termed also mesteque, from the name of a MexicanWith a matter i,* 8 , smal ! er > an d covered with a cottony down, which increases itsior > and is of inferin SS8 * n dyein = i it yields, therefore, in equal weight, much less‘ e compensated in som Pr * Ce l ° tllat oP tbe fine cochineal. But these disadvantagese measure to the growers by its being reared more easily, and