On the use of the Blow-pipe. Ill 



abstract much heat from the fragment under examination, 

 because it must itself be\>ften within the limits of the blue 

 flame ; and my object was, as much as possible, to insulate 

 the fragment. These cones need not in fact be more than 

 one quarter, or one fifth of an inch in length ; for so effectually 

 is the conducting 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 sub- 

 stance experimented upon, and not in any degree to the 

 agency of foreign substance acting as fluxes. 



No. 1. Precious Serpentine — (From Phillips-town, N. Y.) 

 melts instantly into a brownish yellow, blebby enamel : 

 by continuing the heat, ebullition is observed, the colour 

 is nearly or quite dissipated, and numerous wart-like ele- 

 vations appear on the surface. 



No. 2. Precious Serpentine — (From Easton, Pa.) a very lus- 

 trous and beautiful specimen; same result as No. 1. 



No. 3. Precious Serpentine — (Believed to be from Massachu- 

 setts) a dark green specimen ; melts with great ease at 

 first into a dark green blebby enamel ; subsequent effects 

 the same as Nos. 1 and 2. 



Having recently seen the paper of Mr. Keating on the 

 specific identity of Precious serpentine and Marmolite, I 

 was most naturally led to examine this latter substance ; 

 and if a corroboration of that gentleman's opinion were 

 necessary, we might find it in my results! 



No. 4. Marmolite of Nuttall— (Hoboken, N.J.) The effects 

 precisely the same, in all respects, as in Nos. 1 and 2. 



No. 5. Com. Serpentine — (Hoboken, N. J.) somewhat diffi- 

 cult of fusion ; the point of th$ cone alone, or a very 



