110 On the use of the Blow-pipe. 



be melted without difficulty, and even when of considerable 

 bulk." 



Having, in common, I presume with all who have had 

 occasion to refer to the blow-pipe for determining certain 

 characteristic differences of minerals, been much dissatisfied 

 with the limited power of the instrument when acting upon 

 the usual supports of charcoal, platina forceps, &c. ; I was 

 not less convinced, on reading the paper of this gentleman, 

 that his improvements would greatly extend its utility, than 

 gratified by the facility of their application, and the results 

 he had already obtained by their use. With these im- 

 pressions I have recently made a few trials ; which, as they 

 indicate a greater power in the blow-pipe, at least as to one 

 substance, than even Mr. Smithson attributed to it at the date 

 of his letter, this society may not consider wholly uninteresting. 



Not being able to obtain any clay sufficiently refractory 

 for my purpose, though I tried the German, and the English 

 (Stourbridge) 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, how- 

 ever, 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 

 forceps, or attached to the end of a wire, or even of a splinter 

 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 strongest 

 blast of the blow-pipe. 



I conceived, that when a very small quantity of paste was 

 used, the extremity of the wire or forceps must necessarily 



