4 o 4 AURIPIGMENTA.

flakes of the Talc, but they are, tho’ very flexile, not at all elastick, being easily bentinto any posture, and always remaining in it; whereas elasticity is the great distin-guishing character of the Talcs j hence appears the error of those who suppos’d Orpi-ment to be Talc accidentally stain’d. . It is of an extreamly bright and beautiful yellow,not pale but very much the colour of the deeper gold; it is not hard but very tough,easily bending without breaking, and when split it affords an extreamly bright andbeautiful surface, and is in thin pieces beautifully transparent.

It makes no effervescence with Aqua Fortis.

It is not hard enough for the test by steel.

Examin’d by the Microscope, it appears one pure homogene substance, divisible intoplates of extream thinness, and of a beautiful colour, brightness and transparence.

It readily melts with a small fire, and runs into a red fluid mass as thin as water,the Sulphurs appear red while in fusion, but recover their native yellowness whencold again; but this never loses the redness it thus gains, but continues of a fine red,and is then the factitious Sandarach.

If set on sire it burns very freely, emiting a strong smell like that of garlick, andgiving a pale whitish flame, with an admixture of a blueifh green at the edges ; andthe fluid mass below retains a perfectly smooth and equal surface, never bubbling orboiling up ; when it goes out it may be lighted again, and will finally burn all waywithout leaving the least remainder.

It is found in the islands of the Archipelago, in the mines of Goffelaer in Saxony, insome parts of Turky and the East-Indies; the finest now known in the world is aboutSmyrna, where it is not well known of, but might make a very advantageous branchof commerce.

It is sometimes ting’d with an admixture of red Orpiment, and makes with it avery beautiful figure; it makes the finest of all yellows in painting.

2 . Æiripigmentum jlavescens , squammis minoribus.

Small-flaKel, yellow Orpiment.

This is the common Orpiment of the shops, and tho’ greatly inferior to the last spe-cies, is yet a very fine colour. As that resembles in texture the Speculares or broadflak’d Talcs, so this does the Bractearia or spangled ones; and its flakes are usuallylodg’d, like the spangles of those bodies, in an impure and irregular substance, of acoarser nature than Orpiment, and not foliaceous or flaky; these and the mass theyare lodg’d in, have been usually look’d upon as one substance, however, and the wholepowder’d together for use ; but the matter the flakes are lodg’d in, tho’ usually call’d alsoOrpiment, has not the characters of that body, being neither flexile nor foliaceous, butis properly a green substance of the nature of Sandarach, tho’ less pure ; tho’ these bodieshave ail been hitherto call’d Orpiment, the Sandarach itself being call’d red Orpiment,the more accurate distinctions of the Genera of Fossils will not permit these substancesnow being call’d by that name, but determine them a separate Genus, next to be de-scrib’d under the name of Zarnichs, a word us’d indiscriminately by the Arabian Phy-sicians indeed for these, and all the other Orpiments, of whatever figure or colour.

The flaky spangles in these masses, which alone are true Orpiment, are of a veryfine and pure texture, considerably heavy, of very smooth, polite, and glossy surfaces,and very soft and smooth to the touch ; they are perfectly irregular in size and figure,and are many of them so large as to emulate the appearance of the large flak’d Orpi-ment when taken out of the mass ; they are usually, however, much smaller, the fifthor sixth part of an inch being their most usual diameter; they are often of a longhhfigure, tho’ very frequently as broad as long, and are of a pale but bright yellow in-different degrees; tho’ their external appearance does not distinguish them howeverfrom small flakes of the broad flak’d kind, their internal structure and qualities do;they are very easily fissile, like that, into thin flakes, but there is in these a de-gree beyond which we cannot go ; the thinnest flakes we can split these into, notappearing any farther fissile, whereas those of the broad flak’d kind, even in their thin-nest pieces, are seen yet fissile into multitudes of others, if we had eyes and instrumentsto do it j these flakes are very flexile, but less so than those of the other kind, muchmore readily breaking in the attempt to bend them ; they are not at all-elastic, and inthin pieces are very transparent.

They