96 



into the mercury, and the blow-pipe screwed to the other gaso- 

 meter. When we turn the stopcock of the oxygen, the gas drives 

 the water before it into the bell, and rises through it in bubbles 

 as represented in the plate ; but were its elasticity overpowered 

 by that of the hydrogen, the water would be driven back into 

 the longer leg of the syphon, and would add to the oxygen a 

 pressure of eight inches, which is more than enough, as the total 

 force of the hydrogen is seldom more, in my apparatus, than six 

 inches. This safety apparatus (i) might be applied to the hy- 

 drogen, but it is unnecessary, as an excess of oxygen puts out 

 the flame. Fig. 2, represents the nozzle of the blow-pipe as I use 

 it, for that of the inventor did not answer my expectation, ex- 

 cept when its aperture was small ; when it was — of an inch, it 

 became apparent that the gases were not accurately mixed. D 

 and E are the tubes which bring the gases ; they are soldered 

 into holes, drilled through the piece of brass F, so that their aper- 

 tures are at its surface, and their sides in contact, the metal is 

 cut away between them, the piece G applies closely, being fitted 

 by grinding, and it is clear, that the most perfect mixture must 

 take place while the gases pass through it. As this jet is made 

 of brass, it must be kept cooled by any convenient method ; I sur- 

 round it, in general, with moistened lint, but this may be avoid- 

 ed by making it of platina. The widest aperture wliich I have 

 tried is ~ of an inch, and its performance is most satisfactory. 

 When tlie machine is used, the hydrogen cock is opened, and 



(b) It is scarcely necessary to tell the chemical reader, that this is only a modifica- 

 tion of Welter's tubs; the mercury allows room for Uexion of the parts and latitude of 

 adjustment. 



