COMPOUND BLOWPIPE. 



225 



5. The apparatus which I employ, is 

 that represented in the annexed figure, 

 the parts of which are described at page 

 184 ; it is convenient and effectual, and 

 has, for many years, enabled me to per- 

 form all these interesting experiments 

 with great facility, and on a large scale. 

 By adverting to the strictures of Dr. 

 Hare,* and to the statement of the edi- 

 tors of the Annales de Chimie et de 

 Physique, f it will be apparent, that in 

 point of effect, no advantage is gained 

 by mingling the gases, previously to 

 their combustion, f and a serious danger 

 is necessarily encountered, notwithstanding the wire gauze, and oil, 

 and mercury valves that have been interposed in the apparatus of 

 Newman or Brooke, whose figure is annexed. 



\ 



It is a small copper box, (here represented on the left of the page,) 



* Am. Jour. Vol. II, p. 281. t Ibid, Vol. Ill, p. 87. 



t In the apparatus which 1 employ, stout tubes of cast silver are screwed into a 

 piece of platinum, shaped like the lower frustrum of a pyramid, and this is the 

 part of the instrument where the gases issue ; but common brass tubes hard soldered 

 and screwed into a silver frustrum, will answer; care must however be used, that 

 the silver is not melted, which it certainly will be, if allowed to sink into the hole 

 burned into a charcoal support, on which any thing is melting or burning. 



Professor Griscom was so good as to bring this instrument to Yale College, some 

 years since, and we made a series of experiments with it, but with no results differ- 

 ent from those produced by Dr. Hare's blowpipe. In point of pressure, we carried 

 it so far that the copper parallelepiped, was swollen (ill its sides were convex, but no 

 advantage appeared to be gained bv great pressure. 



29 



