J<2 OV MIXED GASES. 



Bxamination of s^'wosphere in the room of it: because when this substance, 

 Mr. Dahon's which is impenetrable to steam, has been removed, theredun- 

 «/gaLs. ^^*' ^^"^ vapour will, according to the theory, flow into the at- 

 mosphere, thereby leaving the moist air of the tube to follow 

 the law of expansion observed by dry air. With a view to 

 find whether this be the case or not, I filled a bottle with run- 

 ning water of the temperature of 59 degrees, which, when 

 carefully poured out again, weighed 7794- grains. The bottle, 

 having a d-ew left stickirig to the sides of it, was placed in 

 water at the temperature of 126 degrees: the mouth, which 

 remained about an inch above the surface, was covered with 

 my hand, care being taken to remove it frequently for an 

 instant to permit the vapour and expanding air to escape. 

 After keeping it in this situation about two mmutes, I secured 

 the mouth in the manner described above, and inverted it in 

 a quantity of the same water, where it was reduced to 59 

 degrees ; in consequence of which it took up 1622 grains of 

 water, leaving a space equivalent to 6172 grains. If the ex- 

 periment be now inverted, 6172 par t^, of air will occupy the 

 space of 7794- such parts when its temperature is raised from 

 59 to 120 degrees; which is nearly double the expansion of 

 dry air iu like circumstances. Fox, according to Mr, Schmidt's 

 experiments, 1000 parts of dry air of 59 dtgrees will become 

 equal lo 1 133^03 such parts, by being heated to 126 degrees; 

 therefore, by the rule of proportion, if 1000 parts give an ex- 

 pansion of 1 133, 03 such parts, 6172 parts give only 820 : but 

 the difference of 7794- and 6172 is 1622, which is nearly the 

 double of 820. The preceding experiment, and others which 

 I have made of the same kind, demonstrate that moist air ex- 

 pands more than dry air under like circums<ances ; and the 

 fact subverts the notion of uncombined elastic vapour mixing 

 with the atmosphere. The accuracy of the fact may be dis- 

 puted; the doubt however is removed by repeating the expe- 

 riment : but so long as my statement remains uncontradicted, 

 the consequences of it to the theory in question, cannot be 

 controverted by argument : for it elastic vapour mix with the 

 air, it does more than merely enter the pores of this fluid; for, 

 according to my experiment, it enlarges these pores at low 

 temperatures, which we know to be impossible, unless the 

 heatof the compound arises to 212 degrees. Those who are 



