2 Description of a new Gazometer and Blow-pipe. 



D and E, the two stop-cocks, fixed in tlicir places, as shown- 

 in the figure. 



The whole being tlius connected, it is obvious that, if the 

 operator open both the cocks and, with his mouth applied to E, 

 suck out or inhale the air out of the superior vessel, the water 

 will then ascend and occupy the plaee of the air thus exhausted ; 

 while the receiver below \\\\{ have gained a proportional quan- 

 tity of atmospheric air which had entered through the stop- 

 cock at D. If both cocks be then instantly shut, the whole of 

 the water, drawn u]) into the superior vessel B, will retain its 

 position and may be there kept for any time. 



Now, if a lamp, v.-itlv a proper wick and lighted, be placed 

 before the blow-pipe C, and the cock E i;e then opened to ad- 

 mit the atmospheric pressure to act, it is evident that the water 

 in the funnel will begin to descend and take its former station, 

 and, consequently, the air in the Woulfe's receiver, having no 

 other way to escape, must be forced out at the aperture of the 

 bloAv-pipe and through the flame of the lamp. 



In this way I have found, that a very fev/ cubic inches of 

 common air are sufficient to impel the fiame of the lamp, while 

 a person can hermetically seal up a small glass tube, or perform 

 some other useful or amusing experiment on minute objects. 



\Mien all the water has descended it must again be raised by 

 suction as before, first opening the stojj-cock D. This must be 

 done at every operation, and will not occasion so much fatigue 

 and continual blowing as when the blow-pipe alone is employed 

 in the ordinary way. It affords also another advantage to an 

 experimentalist, that of having both hands at liberty, which is 

 particularly requisite in the formation of small glass instnuuents. 



Bya very evident contrivance, that of connecting the tubulure 

 at D \\\t\\ a common bladder or receiver containing oxvgen, hy- 

 drogen or any other gaseous fluid, and then ijy inhaling from the 

 orifice or stop-cock at E, as has been already explained, this in- 

 strument can be charged with either of these airs, and in this way 

 it maybe em})loyed as a ga::ometer or blow-pipe. In some cases- 

 the l)low-pipc must be closed or furnished with a stojj-cock, parti- 

 cularly when for certain experiments hydrogen is to be admitted. 



It is almost superfluous to mention another useful application 

 of this apparatus, namely, to convert it into the hydro-pneu- 

 matic blow-pipe of Mr. Tilley, which is so well explained in the 

 Philosophical Magazine for April. This is to be accomplished 

 merely by introducing a long metallic or glass-tube into the ori- 

 fice at D, in place of the stop-cock ; and in such a maimer that, 

 when firmly secured and luted, it may reach from within a very 

 little of the bottom in the water, and proceed uj)wards to the 

 v«ry top of the whole apparatus. This tube^ externally from 



