174 Apparatus for the Analysis of Organic Products. [March, 



tion is to be conducted in a somewhat different manner to that 

 last-mentioned. 



The lamps in this case are to be lighted at the extremity next 

 the o-asometer, and as soon as the gas ceases to be liberated, the 

 next in succession may be employed, and so on to the end ; but 

 instead of suffering the whole of them to continue in flame, it is 

 as well to extinguish a portion, and to sutler only about three or 

 four to remain in operation at once, but taking care to ignite 

 the whole extent of tube at the close of the process. The 

 gaseous products being collected, and their bulk noticed, their 

 analysis is to be conducted in the usual manner, taking care, 

 however, in all instances, to observe the precise temperature of 

 the gases, that their bulk, as also the quantity of aqueous vapour 

 they contain, may be estimated,* and either to equalize the 

 internal and external surfaces of the mercury, or to calculate the 

 volume of gas by the difference of mercurial levels. 



Description of the Plate. 



Fi°\ 1, a a and b b, two long spirit lamps, each having ten 

 burners and wicks, the burners of each lamp sloping towards 

 those of the other, as seen in the end view, fig. 2 ; they are 

 placed in a tin tray, r c, mounted on four feet ; this tray is per- 

 forated in the middle the whole length of the lamps, and as wide 

 as e e, fi°\ 2 ; the object in making the burners sloping is, that 

 they may clear the lamps and approach each other as near as 

 requisite, and yet leave a clear current of air to the flames, and 

 the tray is perforated and mounted on feet to admit this current. 



d d, are springing wires placed at each end of the tray to 

 receive the tubeff, which contains the substance to be analyzed, 

 and to hold it over or between the two rows of flames; by press- 

 ing the finger and thumb on the two shoulders, g g, fig. 2, the 

 wires open to receive the tube, and close on letting go ; and 

 should the tube be shorter than the lamps, an additional support 

 on a leaden foot, fig. 3, is placed through the opening e e of the 

 tray to rise between the flames, and hold the end of the tube ; 

 the tubes are hermetically sealed at one end, and the materials 

 then put in while the tube is straight ; it is then bent at the 

 other end to suit the mercurial trough. 



The tubes are coated with copper foil, wrapped spirally round 

 them ; if each succeeding fold lie on half the other there will be 

 a double coat of copper all the way ; if it lie on two-thirds, there 

 will be three layers of copper, and so on ; by which the glass 

 tube is supported from bending when hot, and becomes very 

 uniformly heated. The spirals are continued beyond the end of 

 the tube, to reach the support, and leave the end within the 

 flames. The dotted lines at h, fig. 4, show the end of the tube, 



« For which very convenient formulae will be found in the ninth edition of Dr. 

 Henry's Elements of Chemistry. 



