278 



Chemical Instruments and Operaiionss 



If the preceding experiment be repeated with an ex'cess of 

 either gas, it will be found that a quantity, equal to the ex- 

 cess, will remain after the explosion. This is very evident 

 when the excess is just equal to one volume, because, in that 

 case, just one volume will remain uncondensed. By these 

 means, a satisfactory illustration is afforded of the simple and 

 invariable ratio in which the gaseous elements of water unite, 

 when mixed and inflamed ; which is a fact of great import- 

 ance to the atomic theory, and to the theory of volumes. 



9. Application of the Volumescope to the illustration of the 

 ratio, in which nitric oxide, and the oxygen in atmospheric 

 air, are condensed by admixture. 



Fig. 5. 



The tube being filled with water by ex- 

 hausting it of air, as in the preceding experi- 

 ment, let five volumes of atmospheric air be 

 introduced into it. Afterwards, by means of 

 a volumeter, or sliding rod gas measure, add 

 at once three volumes of nitric oxide. In the 

 next place fill the syphon, S Y, and the ca- 

 outchouc bag attached to it with water, and 

 pass the leg, Y, up through the bore of the 

 eudiometer lube ; then by alternate pressure 

 and relaxation, the water may be propelled 

 from the bag, through the syphon, into the 

 gaseous mixture, so as to accelerate the ab- 

 sorption. 



If in five volumes of atmospheric air there 

 be one of oxygen gas, there will be just 

 enough to condense two volumes of nitric 

 oxide, by converting them into nitrous acid. 

 Of course of the eight volumes in the tube, 

 three will disappear and five remain. Hence 

 the gas, after the absorption of the red fumes, 

 will occupy the same space as the air before 

 the introduction of the nitric oxide. The extent of the de- 

 viation, from this result, may be measured by introducing 

 hydrogen by means of the sliding rod gas measure, until the 

 quantity added causes the gas to extend to the next gradua- 

 tion. By these means, it is easy to ascertain how much the 

 residue diflfers from five or six volumes. I have generally 

 found it rather less than five volumes. 



