BETWEEN MURIATIC ACID' AND 'CHLORINE. 



339 



now recommend it to the chemical world, as possessing every 

 requisite advantage of convenience, cheapness, safety and pre- 



cision. 



It is represented on the margin. 

 It consists of a glass syphon, having an interior <~=?\JT^9 

 diameter of from T % to T \ of an inch. Its legs 

 are of nearly equal length, each being from 6 to 

 9 inches long. The open extremity is slightly 

 funnel-shaped ; the other is hermetically sealed ; 

 and has inserted near it, by the blow-pipe, two 

 platina wires. The outer, end of the one wire is 

 incurvated across, so as nearly to touch the edge 

 of the aperture ; that of the other is formed into 

 a little hook, to allow a small spherical button 

 to be attached to it, when the electrical spark is to be transmit- 

 ted *. The two legs of the syphon are from \ to \ inch asun- 

 der. 



The sealed leg is graduated, by introducing successively 

 equal weights of mercury from a measure glass-tube. Seven 

 ounces Troy and 66 grains, occupy the space of a cubic inch ; 

 and 34^ grains represent T ^ ¥ part of that volume. The other 

 leg may be graduated also, though this is not necessary. The 

 instrument is then finished. 



To use it, we first fill the whole syphon with mercury or 

 water, which a little practice will render easy. We then intro- 

 duce into the open leg, plunged into a pneumatic trough, any 

 convenient quantity of the gases, from a glass-measure tube 

 containing them previously mixed in determinate proportions. 

 Applying a finger to the orifice, we next remove it from the 

 trough in which it stands, like a simple tube j and by a little 



dexterity, 



* In the figure, the ball should have been represented pendent from a hook. 



