6 4 OCHRES.

vegetable than mineral matter, and evidently owes its origin to the remains of woodlong buried in the Earth; the ashes made by burning this substance, I have try’d inthe usual way of making lixivial salts, from those of vegetables, and have procur’dfrom them a fair, fix’d, alkaline salt, tho’ in a very inconsiderable quantity.

It is dug in Germany and France ; the quantity we have of it is from Cologne, whereit is found very plentifully; nor is England without it, I have obferv’d of it about Bir-mingham, and on Mendip Hills in different places there are many parcels of it, but none sopure as that of Cologne, ours being generally saturated with ochreous or clayey par-ticles, which make it fink in water, and burn but partially and irregularly.

Sect. IV. The Blue and Green OCHRES.

i. Ochra cærulea friability quæ lapis Ar menus author um.Friable , blue Ochre , calTd lapis Armenus.

T HIS is the Lapis Armenus, Cæsalp. 163. Boet. 292. Calc. Mus. 468. Worm.66. Kiw 1/e'f auropuuV, Theophr. IOO. Aet. 1. 2.

It is a very beautiful and very valuable earth, of an even and regular texture, and incolour of a very beautiful blue, sometimes deeper, sometimes paler, and frequent-ly mix’d more or less with green; it is soft, tender and light, of an even and regular,but somewhat dusty surface, it adheres firmly to the tongue, is dry, but not harsh to thetouch, easily breaks to pieces between the fingers, and does not at all stain the hands ;it melts freely in the mouth, and is perfectly pure, leaving not the least harshnessbetween the teeth, but is of a somewhat disagreeable taste; thrown into water it raisesa considerable ebullition, and hissing noise, and aster some time breaks into smalllumps, and from those into a fine powder.

View’d before the Microscope it appears of a fine, but spungy and cavernous texture.It makes no effervescence with Aqua Fortis.

In burning it acquires a little additional hardness, but loses all its colour, coming outof the sire an ordinary pale brown Ochre.

It is a very scarce Fossil, provided that we keep up to this description of it, and callnothing by its name but what is the genuine substance; for it frequently appears, inpart, among masses of the green Ochre, next to be describ’d, and gives occasion to itsbeing call’d, tho' improperly, by its name ; I have only met with it pure from oneplace, which is the great mine of Goffelaer in Saxony; and am inform’d, that even thereit is very seldom found perfectly fine, being frequently spotted with green, and notrarely with black, and sometimes having large lumps of the following Ochre immers’din, and mixt with it ; my particular specimen has indeed a yet greater peculiarity in it,which makes it valuable even for its impurity, for it contains many pieces of a greenarenaceous substance, hereafter to be describ’d under the name of the Chrysocolla of theantients. It is remarkable, that that excellent author Theophrastus was well ac-quainted with its being liable to this mixture, and has mention’d it in express words,L-r! KuawV uuroip uA f^w» h l»v\S ^ua-oxoAAav. The native blue, or Lapis Armenus, havingin it Chrysocolla. This has indeed appear’d to many late writers on these subjects noremarkable account, as they have learn’d to think the green Ochre to be next describ’d,and which I have already observ’d, is frequently mixt with this, the Chrysocolla of theantients; but it will be made evident in its proper place, that this author knew no suchsubstance under that name, and this will help to prove that the Ochre here describ’d,was the true native Cæruleum, or Lapis Armenus of the antients, and probablyin the places whence they had it, it was generally found containing this substance.

Pliny indeed might give us some room to doubt, whether what I have here de-scrib’d, was the substance known by this name to the antients; for he describes theirsto have been of the colour of Chrysocolla, and adds, that the Armenian was the best,because it was the greenest. Lapis eft hie quoque Chrysocollœ modo infedhis, optimumqueeft quod maxime viret-, or as father Hardouin has it, Qui maxime vicinus eft, that is, whichcomes nearest the true colour of the Chrysocolla, Communicato colore cum cœruleo, 1. 3 c ) .p. 688. But this does not at all bring it to agree with the rest of the antients, for theirChrysocolla was certainly green, and their Armenus as certainly blue: I ssou’d therefore,as there is some difference in the copies of Pliny, be inclin’d to believe, either that this

pasiage