112 On the use oj the Blow-pipe. 



small particle attached to it, melts into a white blebby 

 enamel. 



No. 6. Black Flint — (found in chalk) melts with more ease 

 than No. 5, into a white enamel. 



No. 7. Homstone, black — (found on the shore of the Dela- 

 ware, out of place.) Result the same as with the flint. 



No. 8. Homstone, black — (Black Rock, N. Y, imbedded in 

 limestone.) Result the same. 



No. 9. Chalcedony — (shore of the Mississippi, out of place) 

 melts without difficulty into a colourless vesicular glass. 



No. ] 0. Carnelian, deep red — (shore of the Mississippi, out of 

 place) loses colour instantly, and fuses like chalcedony. 



No. 11. Ferruginous Quartz, deep red — (Brooklyn, N. Y. out 

 of place) melts with about the same ease as flint, into a 

 white glass globule, full of air bubbles. 



No. 12. Fer. Quartz, yellowish brown : called by some Horn- 

 stone — (Suffolk county, N. Y.) melts like No. 2. 



No. 13, Common Quartz — (shore of the Delaware, out of 

 place.) This specimen is highly crystalline and trans- 

 parent, but not rock crystal. The results of the experi- 

 ments were, however, precisely similar to those with rock 

 crystal, which are next detailed. 



No. 14. Rock Crystal — (West Canada Creek, N. Y.) For tri- 

 al with this substance, a small crystal, having both termi- 

 nations complete, and of the finest water, was selected. 

 The extremity of the cone is converted into a globule 

 without difficulty ; but it is next to impossible to in- 

 crease the globule first formed. The cone must be very 

 acute, and, after being burned in the flame of a candle, 

 is perceived to be rough and uneven with microscopical 

 particles of the crystal ; the blow-pipe converts the 

 roughness into a smooth and shining surface, and the 

 particle at the very apex into a globule of colourless 

 glass, more or less vesicular. 



I conceive this effect to be most easily produced after 



