2SI4.J Elements of Organic Nature are combined. 405 



natural size in fig. 3. This glass, which I call the receiver, is 

 joined to the tube by a caoutchouc tube* about an inch long, and 

 of the requisite diameter. I tie the elastic tube with a silk thread 

 both to the tube and to the receiver. By this contrivance 1 obtain 

 a joining at once moveable and air tight. The elongated part of 

 the tube penetrates through one quarter of the receiver. Fig. 4 

 shows how that is arranged. 1 attach the tubulure of the receiver, 

 by means of another elastic tube, to a long glass tube filled with 

 muriate of lime. This salt had been heated to redness, but not 

 melted. Of course it preserved a spongy texture, presenting a 

 great deal of surface, without rendering the tube which contains it 

 too heavy. This tube is l'O inches long, and one-fourth of an inch 

 in diameter. At its two ends it was shut by smaller tubes, the 

 openings of which, that entered into the greater tube, were covered 

 with muslin, to prevent the muriate of lime from falling out. These 

 little tubes were firmly attached to the great tube by means of 

 sealing-wax. One of these little tubes communicated with the 

 receiver by means of an elastic tube, the other by means of a similar 

 elastic tube with a curved glass tube, which conveyed the gases to 

 the pneumatic tub. The weight of the small receiver with the two 

 elastic tubes was about 85 grains troy, and that of the tube con- 

 taining the miniate of lime about 77- grains. 



To strengthen the glass tube that was to be exposed to the fire, I 

 surrounded it with a piece of tin plate, very thin, and curved so as 

 to form a tube. This 1 kept fast by means of an iron wire that was 

 wrapped round it. I was obliged to have recourse to this precaution, 

 because no glass tube could have resisted the pressure of the mer- 

 cury in the pneumatic trough, after the glass began to soften in the 

 fire. 



The tube thus secured was placed between bricks, as may be seen 

 in fig. G (in which however one of the two side bricks is not repre- 

 sented). Fire was kindled round the anterior extremity of the 

 tube, taking care to secure the posterior parts from its influence by 

 means of a screen, represented at F, fig. 6". This screen had a hole 

 in it, through which the tube passed ; and as the disengagement of 

 gas began to slacken, 1 drew it by half an inch at a time towards 

 the posterior end of the tube. By this means 1 was enabled to 

 regulate the decomposition at pleasure. In most of my experiments 

 1 burnt from five to eight grains troy of the substance under exami- 

 nation mixed with from 80 to 40 grains of hypcr-oxymuriate of 

 potash. I took care to redden the anteiior part of the tube before 

 the heat began to act upon the mixture. The decomposition 

 Ufually lasted from an hour and a half to two hours. 



I received the gasea funned over mercury in a glass jar capable of 



i I make taete tnbei ia the follow in^ manner i 1 take ■ thin )>irn- of caoutchouc, 

 aad heal it ■ little. I bead it, ami tut oil' from the beading* ■ naall portion with 



■ pail <>t ' il MV The CUl unlace, unite together, and folia a tulir. If llu-v do 



as! oaite, !. t them be prated wiili tin- naili a^aiu.t each other, talcing care not t« 

 touch tbem v.itti the bngt-ri. 



