46 Dr. Woods on the Heat of Chemical Combination. 



find heat or expansion in other bodies is produced. All our 

 powers cannot compress a body beyond the limit where other 

 bodies take up the volume it loses j and if we fad to cause a body 

 to contract without this corresponding expansion, is it probable 

 a body can of itself part with its heat or become smaller, inde- 

 pendent of the expansion that is generated when pressure is used? 



(18.) The liquefaction of the gases by Faraday will illustrate 

 my meaning practically. When pressure was first applied to 

 some of the gases in order to liquefy them, no other effect than 

 a diminution of volume to a comparatively small extent was pro- 

 duced, the solid bodies surrounding the gas being capable of 

 taking up the volume lost by it only to a limited extent. Solid 

 carbonic acid and rether being now placed in the vicinity of the 

 gas, and their volume at the temperature employed, or when 

 gaseous, being so enormous compared with the state of solidity, 

 expansion to an immense extent went on, the corresponding con- 

 traction being supplied by the gas under pressure, and conse- 

 quently, both changes having been provided for, success was 

 obtained. This experiment proves, — 1st, that the contraction 

 of the gas could not go on without the corresponding expan- 

 sion; 2nd, that the carbonic acid in expanding took away a 

 like amount of contraction; and 3rd, that as both expansion 

 and contraction require an opposite change to be going on at 

 the same time, they cannot be due either to attraction or repulsion. 



(19.) Just to fix my ideas more firmly in the mind, I will say, 

 I do not believe the nebular hypothesis to be correct. It assumes 

 the nebula? to be in a state of vapour or mist, gradually con- 

 tracting to form stars. Now if no other body sufficiently large 

 be expanding so as to produce the opposite effect, it is contrary 

 to all our other experience if such contraction take place. 



I believe our atmosphere is limited in extent, as it, as well as 

 all other bodies, has a captain volume, just as I believe steam can 

 expand to a limited distance if relieved from all pressure, this di- 

 stance corresponding with the amount of contraction suffei-ed by 

 the body which heated it. 



And I think, if we admit that the particles of matter only move 

 as they are influenced by, or rather as they are accompanied 

 with, an opposite movement, and not by any force exerted be- 

 tween themselves, we have a beautiful proof, not only of the 

 stabdity of our system, but that the arrangements of matter 

 never could have exceeded their present limits ; that no meeting 

 by chance of atoms in space could occur ; that all power, as well 

 as all matte?-, has been supplied by the existing state of things, 

 inasmuch as nothing can be accomplished without its opposite. 

 Nothing therefore, neither force nor matter, can be added or 

 taken away ; everything seems to have come literally "finished" 



