1821.] Fhanomena of Heat, Gases y Gravitation y B^c. 415 



sum of the two excesses of the pressures on the further and 

 nearer sides of the two particles, will be, perhaps, nearly equal 

 to the sum of the two whole pressures on their further sides. 



Different degrees of flatness will evidently cause different 

 degrees of attraction and cohesion. But it is not to flatness 

 alone that the cohesion, affinity, &.c. of the particles may be 

 owing ; a proper adaptation of the parts or figure of one particle 

 to the parts or figure of another, may as much conduce to the 

 cohesion of the particles as flatness ; and hence the greatest 

 scope is afforded for expounding the various phaenomena of che- 

 mical action. Suppose, by way of example, any compound 

 particle whose component particles have a certain adaptation in 

 figure, be brought into contact with any other particle, whose 

 component particles have likewise a certain adaptation of figure; 

 then if the figures of the elementary particles of either of the 

 compound particles have, individually, or in any degree of 

 aggregation, a much less adaptation to one another than they 

 have to the figures of the elementary particles of the other com- 

 pound particle, a new combination will instantly ensue ; and one 

 or more particles with properties, probably very different from 

 those of the primitive compound particles, be formed. In this 

 way, therefore, decompositions and precipitations may take 

 place, or new compounds be made ; and thus the various phae- 

 nomena of chemical affinity may lesult entirely from the sizes 

 and figures of the component particles. Besides, as an aggre- 

 gation or division of the elementary particles will generally 

 accompany every chemical change, so also will an elevation or 

 a depression of temperature, and, therefore, the change that 

 ensues in the temperature might serve for an index to point out, 

 in some measure, the kind of change that has been effected ; 

 and by this means possibly some conjectures might be formed of 

 the physical composition of many bodies. 



I might now extend my observations to the solution of many 

 other phaenomena of nature. 1 might show that the fluidity of 

 bodies arises from their particles not having a sufficient adapta- 

 tion of figure, to make their cohesive tendency overcome the 

 effects of their mutual impulses, due to the limiting temperatures 

 at which they are fluid. I might show that the boiling points of 

 fluids depend chiefly on the magnitude of their particles, and 

 their freezing or congealing on the magnitude and adaptation 

 conjointly. I might show how different combinations of the 

 ,same elements might produce bodies differing essentially in 

 colour, sohdity, specific gravity, &c. such, for instance, as char- 

 coal and the diamond ; and, therefore, that notwithstanding 

 such bodies may be composed of precisely the same constituent 

 parts, a transmutation from the one to the other can, perhaps, 

 never be expected, unless by decomposing them into their con- 

 stituent elements, and then discovering some method of reasso- 



