1820.] the Analysis of organized Substances, 191 



bottom of the wooden dish, H, and the dish is placed upon the 

 support, D, which has a hole in its centre adapted for receiving 

 it. F, is a spirit lamp with a circular wick, like the common 

 Argand lamp. This lamp stands upon a support, C (fig. 1), 

 capable of being moved up and down by means of the counter- 

 poize weights, MM, attached to the lines passingoverthe pulleys, 

 L L, in a manner easily understood by a bare mspection of the 

 figure. The tube, G, passes through the centre of the lamp, and 

 thus is enveloped equally on all sides by the flame. The gaseous 

 products are collected in the graduated tube, K, which had been 

 previously filled with mercury, and inverted in the wooden dish 

 above described likewise partly filled with mercury. The external 

 glass tube, I, is furnished with a brass screw cap by which it 

 can be attached at pleasure to the piece of brass fixed in the 

 bottom of the wooden dish, in the manner shown in fig. 2. The 

 use of this tube is to afford an easy means of equalizing the 

 height of the mercury on the inside and outside of the tube, K, 

 and thus to supersede the necessity of calculation. N is a cir- 

 cular tin plate, with a hole in the centre, of such a size as to 

 admit the tube, G. This plate is suspended by wires from the 

 support, D ; and its use is to prevent the action of the flame of 

 the lamp upon the wooden dish, H, and its contents. Fig. 3 is 

 a small mercurial gasometer, whi.ch may be used instead of the 

 dish and graduated tube when it^s desired to take the specific 

 gravity of the gaseous products. -The tube, G, in this case is 

 fixed into the brass cap, e, by means of a cork. When the 

 above apparatus is employed, the lamji, F, is raised to the upper 

 part of the tube, G (two or three inches of which at this part is 

 filled with pure oxide of copper only), and there permitted to stay 

 till the tube becomes red-hot. When this is the case, it is 

 depressed a little, and another portion of the tube similarly 

 heated, and so on, till the whole of the tube has been heated in 

 succession, when the operation is completed. The gaseous pro- 

 ducts are then analyzed in the usual manner, if the substance 

 submitted to the operation has contained azote ; if not, the 

 "whole of the gas (except a very minute quantity) will be carbonic 

 acid. 



The proportion of hydrogen in a substance may be ascertained 

 in several different ways by means of this apparatus. A mode I 

 have commonly practised is (after filling it as usual) to exactly 

 counterpoise the tube, G, in a dehcate balance, and when the 

 process is finished to see how much it has lost in weight by the 

 operation. The quantity of gases produced by the same 

 substance being previously known, the quantity of hydrogen may 

 be thus readily estimated. Another mode is to actually collect 

 the water formed, and to weigh it. This may be effected by 

 having the tube in the shape represented in fig. 4. At the end 

 of the operation, most of the water will be found collected in the 

 part O, and to ensure the collection of the rest, another tube fiiUed 

 with dry muriate of lime may be attached to the end, P. Another 



