00 APPAllATUS FOR "THE ANALYSIS OF GASSES. 



Method of as- The inflammable gas, which has found its way into the 

 lelkluTl'hidro- rece i yer *> is always present in too minute a quantity to 

 gen. compose, with the residuary oxigen, after the removal of the 



carbonic acid, a mixture capable of being inflamed by the 

 electric spark. To ascertain its precise quantity, it is ne- 

 cessary to have recourse to another operation. After trying, 

 eudiometrically, the quality of an aliquot part of the gas 

 in the receiver b, let a similar aliquot part be deprived of 

 its carbonic acid, and then mixed with a portion of pure hi- 

 drogen gas, not exceeding one third or one fourth the esti- 

 mated bulk of the oxigen which it contains. Detonate the 

 mixture, and observe the amount of- the diminution after 

 the explosion ; the products of the combustion ; and the 

 quantity of oxigen gas consumed. After subtracting, from 

 the total expenditure of oxigen, half the bulk of the added 

 hidrogen gas, the remaining number shows; kow much oxi- 

 gen has been absorbed by the combustible gas contained in 

 the residue. By the rule of proportion, it may be deter- 

 mined, how much carbonic acid would have been produced* 

 by the oxigenation of the whole of the combustible gas, and 

 what quantity of oxigen it would have Saturated. 

 Objection. The mosit obvious objection to this method of analyzing 



Absorption of ^ e com p und gasses is, that the real proportion of the pro- 

 bonic acid by ducts, resulting from their combustion, may perhaps be 

 the water. disguised, in consequence of the absorption of a part of the 

 carbonic acid by the water, over which the experiment is 

 made. By frequent trials, however, I find that this is a 

 This trifiin". source of errour too trivial to be deserving of consideration ; 

 and that the proportion of carbonic acid, thus generated, 

 exceeds what is composed by the rapid combustion of the 

 same gas over mercury. When the operator has acquired 

 sufficient dexterity, the interval of time between the com- 

 pletion of the combustion and the admeasurement of the 

 residue is too small, to allow an absorption to any notable 

 amount. It must be observed, also, that the carbonic acid 

 constitutes only a small part of the residue ; and is, for this 

 reason, very little acted on by water, conformable to a prin- 

 ciple which I have explained in the Philosophical Transac- 

 tions for 1803, p. 2/4*. I believe, therefore, that, with an 



•Journal, vol. V, p, 133. 



attention 



