WATER. 



219 



and also by some separate instruments called volumeters, and sliding 

 rod gas measures. To one of his eudiometers a barometer gage is 

 attached, by which the amount of absorption is accurately ascertain- 

 ed. The ignition of the platinum by the calorimotor, for the purpose 

 of inflaming the gases, is an elegant and novel method of operating ; 

 the various modes of measuring the gases are ingenious and accur- 

 ate, and the detailed description of all the instruments and operations 

 may be found in Dr. Hare's Compendium, and in the Am. Journal. 

 We subjoin the figure, and an abridged description of the simplest 

 of these eudiometers. 



Hydro-oxygen Eudiometer of Dr. Hare. 



A A 



W W 



W W Two brass wires passing through the socket S, and appear- 

 ing within the glass detonating tube G, where they are connected at 

 the top by a soldered arc of platina wire, visible in the drawing. 

 One of the brass wires is soldered to the socket. The other is fast- 

 ened by means of a collar of leathers, packed by a screw, so that it 

 has no metallic communication with the other wire, unless through 

 the filament of platinum, which is called the igniting wire. 



At A is a capillary orifice in the glass tube, which is opened and 

 closed by the lever and spring, seen in the drawing, and it may be 

 guarded by a gallows screw, in the iron staple A A, which may be ap- 

 pended to the instrument by pivots at S, and the opposite point, and 

 may be dropped out of the way when the eudiometer is to be charged. 



R The sliding rod, is acurately graduated to about 160, and to 

 diminish the chance' of leakage, a stop cock may be interposed be- 

 tween the sliding rod and the detonating tube. 



B represents a detonating tube, to be discharged by an electric 

 spark ; it may be screwed into the socket S, instead of the tube G. 



