■TO 



1825.] Scientific Notices — Mineralogy. 



have now to acquaint our readers with Mr. Heuland's purchase 

 of that of the Marquis de Dree. The Parisians, however, have 

 still to admire the private collection of the late King of France 

 under the superintendance of Count Bournon, that of the Jardin 

 des Plantes, and another, highly instructive, at the College of 

 Mines. Besides every Professor of Mineralogy at Paris has a 

 collection, and that of MonS'ieur Brochant de Villiers is now the 

 most valuable of any private individual there. With the excep- 

 tion of two other private collections o^ peculiar note on the Con- 

 tinent, all the others from thence have by degrees found their 

 way to this country. 



5. Supports for Minerals before the Blottpipe. 



Our readers will remember the interesting paper by Mr. 

 Smithson on this subject, which appeared in the Annals (f P/ii- 

 losophy, vol. vi.p. 412, N. S. Lieut.-Col. Totten, of the United 

 States, has lately published some experiments on the same sub- 

 ject. His process is a modification of that adopted by Mr. 

 Smithson. We extract a part of his memoir. 



" Not being able to obtain any clay sufficiently refractory for 

 my purpose, though I tried the German and the English (Stour- 

 bridge) clay, used for crucibles by glass-blowers, and two or 

 three specimens called pipe-clay, I had recourse to the minerals 

 which I designed to expose to the action of the flame ; this is 

 Mr. Smithson's third process. Instead, however, of taking upon 

 the point of the wire a very minute portion of the paste made of 

 the powdered mineral, according to Mr. Smithson's method, I 

 formed a paste by mixing the powder with very thick gum water, 

 and rolling a little of it under the finger, formed a very acute 

 cone, sometimes nearly an inch in length, and generally about a 

 twentieth of an inch in diameter at the base. These cones, being 

 held by the Ibrceps, or attached to the end of a wire, or even of 

 a sphnter of wood, may be directed accurately upon the minutest 

 visible particle ; and being a little moistened at the point with 

 saliva, the particle will adhere to the very apex under the stroufj-- 

 est blast of the blowpipe. 



I conceived that when a very small quantity of paste was 

 used, the extremity of the wire or forceps must necessarily 

 abstract much heat from the fragment under examination, 

 because it must itself be often within the limits of the blue flame ; 

 and my object was, as much as possible, to insulate the frag- 

 ment. These cones need not in fact be more than one-quarter 

 or one-fifth of an inch in length ; for so effectually is the con- 

 ducting property of the mineral substance destroyed, by 

 destroying the continuity of its particles, that one of these cones, 

 of the length of half an inch, may be held at the base by the 

 fingers with impunity, while the apex is in the focus of heat. 



One great advantage of this method over the others is, that if 

 fusion ensues, it is owing entirely to the nature of the substance 



