Description of a Compound GasometcK 35 



pillars BB, which are fixed into the base cc. D and E are 

 two class jars eleven inches diameter and eighteen inches 

 high, fixed to the base by means of two brass rings about 

 one inch broad. F is a glass globe twelve inches diameter, 

 sustained in its place by means of the tripod mm', this, and 

 the two glass jars, are provided with brass collars and 

 caps n,n,n; into these are screwed, and properly fixed, the 

 tubes and cocks o,h,p,k,(j,l, s,i, I. Through a collar of 

 leathers on the cylinder A passes the metal tube Y, about 

 four-tenths of an inch diameter, extending down the tin or 

 brass tube G (of about two inches and a half diameter) to H : 

 this tube is moveable through the collar of leathers, and may 

 be elevated and depressed at pleasure until the desired pres- 

 sure is attained, h and i are two tubes passing from the 

 cvlindcr A into D and E, and are recurved under the cap, 

 as represented at y, fig. 2. y is a cock for exhausting the 

 balloon F, and behind it is a glass tube through which passes 

 the wire b, nearly meeting the end c of the recurved tube kc, 

 for igniting the gas by the electric spark in the composition 

 of water by the combustion of hydrogen in oxygen, as de- 

 scribed by M. Van Marum (Phil. Mag, vol. ii. p. 85). The 

 jars D and E are provided with, cocks jrx, cemented into 

 apertures formed for that purpose. The tubes h,i,k,l, being 

 fixed with screucd flanches, may be easily removed, as also 

 the caps n,n,n, which are screwed to the collars so as to be 

 perfectly air-tight. 



The gasometer being thus prepared, nothing more is ne- 

 cessary to charge it than to fill the cylinder A, screw in the 

 collar of leathers, and adjust the tube YH, so that the end 11 

 be on a level with the upper parts of the plugs of the cocks 

 o,p, s, t, all of which must be opened. Open also k and i, 

 by which means D and E will be filled. Shut h,p,s,i, and, 

 having the gas-holder V ready, screw the cocks v and z on 

 to t and r. Open these cocks, and the gas in V will be 

 transl'erred into E : charge it again with the gas intended 

 for D, and proceed in the same manner. The vessels D 

 and E should hif. provided with a scale expressing in cubic 

 inches the quautliy of gas at any time in them. Having 

 d*;tfTmined the rc(^uisite pressure, adjust the tube YH ac» 

 C a cordingly. 



