Philosophical Transactions Volume 172, PT. 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 edition. Excerpt: ... little less difficult to condense than hydrogen, show a slight increase in log. decrement. Carbonic anhydride, which liquefies at a pressure of 56 atmospheres at 15 C, increases so rapidly in viscosity that at this pressure it would have a logarithmic decrement of about 1 "3, representing an amount of resistance to motion that it is difficult to conceive anything of the nature of gas being capable of exerting. Kerosoline vapour is rendered liquid by pressure much more readily than carbonic anhydride. Its curve of viscosity on diagram A shows a great increase in density for a very slight access of pressure (705). 709. Maxwell's law was discovered as the consequence of a mathematical theory. It presupposes the existence of gas in a "perfect" state--a state practically unknown to physicists, although hydrogen gas very nearly approaches that state. An ordinary gas may be said to be bounded, as regards its physical state, on the one side by the sub-gaseous or liquid condition, and on the other side by the ultra-gaseous condition. A gas assumes the former state when condensed by pressure or cold, and it changes to the latter state when highly rarefied. Before actually assuming either of these states there is a kind of foreshadowing of change, with partial loss of gaseity. When the molecules, by pressure or cold, are made to approach each other more closely, they begin to enter the sphere of each other's attraction, and therefore the amount of pressure or cold necessary to produce a certain density or viscosity is less than the theoretical amount by the internal attraction exerted on each other by the molecules. The nearer the gas approaches the point of liquefaction the greater is the attraction of one molecule to another, and the...