428 Dr, Clarke upon a new Blowpipe, [June, 



From the summary nature of my little volume the above has 

 been omitted, as well as a great deal more on some other points, 

 which I fear will in consequence be liable to be misunderstood. 

 i hope, however, to have it in my power to obviate this objection 

 at no very remote period. I am, yours truly, 



William Prout. 



Article V. 



Upon a new Ili/dro-Pneumatic Blowpipe, so constructed as to 

 maintain during two Hours, uninterruptedly/ , a Degree of Heat 

 capable of melting Platinum ; and this by propelling the Flame 

 of a small Wax Taper with Atmospheric Air. By Edward 

 Daniel Clarke, LLD. Professor of Mineralogy in the Univer- 

 sity of Cambridge, Member of the "Royal Academy of 

 Sciences at Berhn, &c. &c. 



(To the Editor of the Annals of Fhilosophy.) 



SIR, Camhridge, May 15, 1821. 



To the various successive improvements which the blowpipe 

 has received, we may now apparently add another, possessed 

 of considerable advantages : — I allude to that form of the instru- 

 ment wherein the air is propelled from a jet by the pressure of a 

 quantity of water; this being the kind of blowpipe on which 

 these improvements are founded. 



The advantages of the old instrument consisted in the opera- 

 tor having both his hands at liberty ; and in the relief which it 

 afforded from that fatigue and possibihty of injury to the lungs 

 incident to a protracted restraint on their free action, to which 

 persons using the common mouth blowpipe were liable. To 

 these advantages, which the new instrument also possesses, we 

 may add the following : 



1 . Either common air, or any other gaseous fluid may be used 

 for the propelling current, by condensing it in the reservoir, and 

 thus experiments may be made on the fusing powers of the dif- 

 ferent gases with perfect ease and convenience. 



2. The power of entire exhaustion possessed by the new 

 instrument, ensures the operator from any admixture of common 

 air, where oxygen gas, or any other gaseous fluid is to be 

 employed. 



3. The old instrument, although very useful for bending tubes, 

 or other ordinary purposes, required to be repeatedly restored to 

 action by fresh supplies of air, at intervals seldom exceeding five 

 minutes, in the common-sized instrunjents. In the new instru- 

 ment tliere is this great improvement ; that a steady flame of 



