1879.] Properties of Matter in the Gaseous State. 



321 



in fact, the same correspondence is found with all the phenomena 

 investigated. 



We may examine this result in various ways, but in whichever way 

 we look at it, it can have but one meaning. If in a gas we had to do 

 with a continuous plenum, such that any portion must possess the 

 same properties as the whole, we should only find the same properties, 

 however small might be the quantity of gas operated upon. Hence, 

 in the fact that we find properties of a gas depending on the size of 

 the space in which it is enclosed, and on the quantity of gas enclosed 

 in this space, we have proof that gas is not continuous, or, in other 

 words, that gas possesses a dimensional .structure. 



In virtue of their depending on this dimensional structure, and 

 having afforded a proof thereof, I propose to call the general pro- 

 perties of a gas on which the phenomena of transpiration and impul- 

 sion depend, the Dimensional Properties of Gas. 



This name is also indicative of the nature of these properties as 

 deduced from the molecular theory ; for by this it appears that these 

 properties depend on the mean range, a linear quantity which, ceteris 

 paribus, depends on the distance between the molecules. 



In forming a conception of a molecular constitution of gas, there is 

 no difficulty in realizing that there must exist such dimensional pro- 

 perties ; there is, perhaps, greater difficulty in conceiving molecules 

 so minute and so numerous that in the resulting phenomena all 

 evidence of the individual action is lost ; but the real difficulty is to 

 conceive such a range of observational power as shall embrace, on the 

 one hand, a sufficient number of molecules for their individualities to 

 be entirely lost, while, on the other hand, it can be so far localized as 

 regards time and space, that, if not the action of individuals, the 

 action of certain groups of individuals, becomes distinguishable from 

 the action of the entire mass. Yet this is what we have in the phe- 

 nomena of transpiration and impulsion. 



Although the results of the dimensional properties of gas are so 

 minute that it has required our utmost powers to detect them, it does 

 not follow that the actions which they reveal are of philosophical im- 

 portance only ; the actions only become considerable within extremely 

 small spaces, but then the work of construction in the animal and 

 vegetable worlds, and the work of destruction in the mineral world, 

 are carried on within such spaces. The varying action of the sun 

 must be to cause alternate inspiration and expiration, promoting 

 continual change of air within the interstices of the soil as well as 

 within the tissue of plants. What may be the effect of such changes 

 we do not know, but the changes go on ; and we may fairly assume 

 that, in the processes of nature, the dimensional properties of gases 

 play no unimportant part. 



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