Part 47

The author ſpeaks here of ſuch as he obtained by precipitation from acids, but the native TERRA PONDEROSA aerata (ſee note at page 28) has a ſpecific gravity of nearly 4, 338. W.

Footnote 39:

Opuſc. vol. i. p. 21, 398.

Footnote 40:

N. Acta Upſ. Vol. II. page 198.

Footnote 41:

Opuſc. chem. vol. I, page 23.

Footnote 42:

Opuſc. chem. vol. I, page 398.

Footnote 43:

Opuſc. chem. vol. II. p. 29, 373.

Footnote 44:

Profeſſor Bergman does not here ſeem to be ſufficiently aware of the difference between our Devonſhire pipe clay, and that which is uſed in the manufacture of porcelain. The former, in an open fire, burns to a blueiſh grey, or pidgeon colour; the latter remains white. The former ſeems to be the ſame as the Cologne and Maeſtricht pipe clay, of Cronſtedt, §78; the latter is a decayed Feldſpath, and conſequently, according to our author, (§ 130) contains magneſia. Our porcelain clay, likewiſe, has quartz, chryſtals, and mica mixed with it, parts of the granite which it originally compoſed. Before it is uſed the quartz is ſeparated, but the mica remains. I am indebted to my friend Mr. Watt for theſe obſervations. W.

Footnote 45:

I have taken the liberty to add this ſpecies upon our author’s own authority. See BERGMAN Diff. de Lithomarga, page 13.

Footnote 46:

N. Acta Upſal. vol. III, page 121.

Footnote 47:

Opuſc. vol. I, page 291, 292.

Footnote 48:

It is probable, that in another edition, the author may ſee reaſon to ſeparate the mica from the talc; as ſome experiments I have made, though yet too imperfect for publication, ſeem to indicate the neceſſity of ſuch a meaſure. W.

Footnote 49:

Opuſc. vol. ii. p. 49.

Footnote 50:

Hiſt. des Plantes de la Gujane. 1774.

Footnote 51:

Dr. SWEDIAR lately preſented a paper to the Royal Society, from which it appears highly probable that Ambergriſe is nothing but the indurated fæces of the Sperma Ceti whale, who feeds upon the cuttle fiſh. He has found the beaks of that fiſh intermixed with the ambergriſe, in the form of black ſpots. W.

Footnote 52: