500 CONSTlTUTIOtJ OF MIXKC GASE5» 



thefe I fliall mention only a few; fince the theory will receive 

 from yourfelf all the elucidation that its eftablifliment can re- 

 quire. 

 Light and heavy ]. If Cadh gas be a vacuum to every other, a heavier gas 

 t3neoJfly/^°"' ^'""'<-^ afcend into a hghter one, without the aid of agitation; 

 and on the contrary a lighter one fnould defcend into a heavier 

 one. That this is a61ually the fafl, and under circumflances 

 very unfavourable to their mixture, your own experiments 

 have fully proved. 

 Su]phuret takes 2. The hypothefis explains why fulphuret of potafh with- 

 noi:^a"itat°d ^"^ ^^^^'^^ oxygcn from the air without agitation, and whether 

 placed at the top or at the bottom of a jar; for it acts as if tlie 

 abforbed gas were the only one prefent in the veffel. 

 Abforbable gafes 3. It explains why the laft portions of common air are ex- 



expe t e laft pgHed from water by carbonic acid, and other abforbable gafes. 



portions of com- ' . -'■■ ... 



mon ah- from For thefe gafes act as a vacuum to the air contained in the 

 water. Water, which muft therefore necefTarily quit its place. It 



folvcs alfo the problem how to expel completely any gas from 

 water; for to effedt this, the water mud fucceffively be agi- 

 tated with portions of fome other gas of the greateft attainable 

 purity. Thus to expel atmofpherical air entirely from water, 

 it may be agitated with pure carbonic acid gas ; but as the li- 

 berated common air preffes on that remaining in the water, 

 according to the proportion it bears to the fuperincumbent car- 

 bonic acid, the gas thus employed mufl be removed, and freflj 

 and pure portions ufed in fucceffion. 

 Eeft method of 4. By applying the fame general law, we are taught how to 



impregnating efFeft the higheR at talnable impregnation of water with any 

 water with a gas. . . .... 



gas. There could be no difficulty in accoraplithing this objedt, 



if the gas and water were both abfolulely uncontaminated by 

 admixture with other gafes; but when pure carbonic acid is 

 agitated with water, atmofphencal air is extricated, which, 

 mingling with the carbonic acid, leflens its denfity. To ob- 

 viate this difficulty as much as poffible, a quantity of water, to 

 be impregnated fully with carbonic acid, ffiould be agitated 

 with feveral fucceffive portions of the pureft poffible gas. The 

 unabforbed refiduum ffiould alfo be very large, in order that 

 the carbonic acid may bear a large proportion to other aeriform 

 fubftances accidentally mixed with it. 



Thefe are, doubtlefs, only a few of the phenomena, to the 

 explanation of which your theory may be fuccefsfully applied; 



and 



