On Vegetalle and Animal Analyst. 61 



could succeed in operating the transformation so as to col- 

 iect ail the gase*, this analysis would be accomplished with 

 Very great precision and simplicity. Two obstacles pre- 

 sented themselves: one was to burn completely the hydro- 

 gen and the carbon of these substances, and the other to 

 operate the combustion in close vchsels. 



We could expect to surmount the first difficulty onlybv 



means ofthe metallic oxides which easily give up their oxygen, 

 or by the hyper-oxygenated muriate of potash. Some experi- 

 ments soon made us give the preference to the above salt 

 which succeeded beyond all expectation. It was not quite' 

 so easy, however, to overcome the latter difficulty; for we 

 could not attempt combustion in a retort full of mercury. 

 To prevent the matter from being burnt, the retort must 

 have been broken: it became neces'sary to find an apparatus 

 therefore, m which we might — ' 



1. Burn portions of substance so small as not to fracture 

 the vessels. 



_ 2. To make a great number of successive combustions, 

 in order that the results might be perceptible. 

 3. To collect the gases as thev were formed. 

 We now exhibit to the class 'an apparatus of the above 

 description. It is formed of three distinct pieces : one is a 

 very thick glass tube, closed at its lower extremity bv the 

 blow-pipe, and open at its upper end, about two decim'ctres 

 in length, and eight millimetres in breadth; it has laterally 

 five centimetres from its aperture a very small tube also 

 of glass, which is soldered to it, and which resembles that 

 which we should adapt to a retort for receiving the o-ascs. 

 1 he other piece is a copper ferule into which we insert the 

 open extremity of the large glass tube, and with which it is 

 united by means of a mastic which melts only at 40°. The 

 last piece is a peculiar kind of stopcock, in which ihe'whole 

 merit of the apparatus consists. The key of this stop- 

 cock has no hole through it, and turns in every direction 

 without giving vent to the air: there is simply about the 

 middle ot It a cavity capable of receiving a small pea: bul 

 this cavity is such that being in its upper position, it cor- 

 responds to a small vertical funnel which penetrates the 

 socket, and of which it forms in sonic measure the extremity 

 ot the beak, and which v. hen brouglu back to its lower no- 

 sition communicates with, and is a continuation of, the 

 bodyot the stop-ci.ck, which is hollow, and is screwed to 

 the ferule. Thus, when we put small fraomcnts of anv 

 matier into the funnel and turn the kcv, the cavity is soon 

 fiJkd, andcainus tiie matter into the body of the siop-cock, 



Irom 



