DESCRIPTION •F A BLOW-PIPE. ^S- 



as readily as copper or brafs wire would have done, I foon —canfed by tfie 

 perceived from Jhe colour of the flame of the hydrogen and volauluation of 

 the depcfit of white clouds on the infide of the glafs, that the 

 rapid folution of the finely powviered zinc ufed to afford the 

 gas, that this metal was a6lually fufpended or diflTolved in the 

 gas, and hence the zinc ading to the platina fufed the latter. 

 It may be perhaps ufefiil to know this fadt, which occurred 

 during the public ledure, 



Your's, as ufual, 



AMICUS. 

 JuIj/2, 1804. 



VI. 



Defcripiion of a Blow-Pipe a^ing hy the Prejfure of Water, by the 

 Abbe Melograni. In a Letter Jrom Mr. G. B. Greenough. 



To Mr. NICHOLSON. 

 'SIR, 



No. 15, Parliament- Street, 

 Augufi 13, 1804. 



JlT ERMIT me to make you acquainted with the principle of Blow-pipe fup- 

 an inftrument invented by the Abb^ Melograni, and ufed by ^^^^^1,^^^^^' 

 him at the Royal Mineralogical Collection at Naples, as a changing their 

 fubftitute for the blow-pipe. I regret that I cannot fend you P°^^*^°"*« 

 an accurate account of its conftru£Hon, as I made no fketch 

 at the time, and fpeak only from recolledlion. 



Two hollow glafs globes of convenient lize were connoted 

 together by two brafs tubes laid along-fide each other, one of 

 them having a valve or flop cock, I am not fure which, at 

 each end, and a fide tube of the fame metal going off from the 

 middle at right angles. The frame was attached to the verti- 

 cal tubes, foas to allow the globes to circumvolve each other. 

 Let the lower globe be half filled with water and inverted; 

 Then the water in A (Fig, 2. Plate IV.) running into B 

 through the tube C, will force a conftant flream of air into 

 the tube D, and thence, the upper orifice being clofed, into 

 the fide-tube E, at the mouth of which the candle is placed. 

 When the water is nearly run out invert the globes. 



If 



