THE CHEMICAL HAKMONICON. 



370 



ility of producing the necessary draught, that is, the 

 instant renewal of air required for combustion. 



The apparatus for producing notes in this manner has been termed 

 le chemical harmonicon. It consists of a tube of glass or of sheet 

 ietal, which is best clamped in the retort-holder, and of a small 

 is-burner, which reaches to some distance into the tube. The 

 irner is a small straight tube, tapering towards the upper 

 id, which has an aperture of O5 or l mm ; it is usually a glass tube, 

 *avm to a point, connected by means of an indiarubber tube with 

 gas-pipe, or with an apparatus for making hydrogen, and clamped 



!<>,. 229 



real si~e). 



ad arm attached to the retort-holder. The sounding tube may 

 tve a width of from 15 to 30 mm , and a length of from 20 to 100 cm . 

 te most convenient size of the flame and the most suitable height of 

 *;3 burner in the tube should be ascertained by trial ; both are ap- 

 pximately represented in fig. 229. If coal-gas is used, the size of 

 1i > flame requires more careful regulation than for a hydrogen 

 *;tne; but even in the latter case it is desirable to have a stop-cock 

 1 regulating it, and the apparatus in fig. 156 is therefore prefer- 

 *le to that in fig. 154. 



