246 Rev. J. B. Emmett on the [April, 



teral triangles, in which equilibrium is preserved ; for since the 

 particles are equal and similar, and a, b, mutually balance each 

 other, b and c, c and a, are in equilibrio ; and if c be brought 

 nearer to b or a, it is repelled (Prop. I.) ; if removed to a greater 

 distance, it is attracted; therefore the triangles a b c, a c e, &c. 

 will be equilateral. Q. E. D. 



Prop. III. 



Liquids will be expanded by heat and contracted by cold. 



It has been demonstrated in a former paper that by increasing 

 the heat, the repulsive force of every calorific atmosphere is 

 increased ; and upon the surface of a particle of a liquid, it 

 exceeds the force of attraction. Hence (Lemma 2), the distance 

 of the point in which the forces are in equilibrio is increased ; 

 therefore the particles separate. Conversely, diminish the heat, 

 and the particles approach, or, in other words, the volume con- 

 tracts. Q. E. D. 



Prop. IV. 



Solids absorb heat during fusion. 



By Prop. 1, the particles separate during fusion ; hence the 

 calorific atmospheres are enlarged, and particularly where they 

 are most dense; therefore, caloric will be absorbed. Q.E. D. 



Cor. 1. — Hence, during fusion, some bodies will absorb more 

 heat than others. 



Cor. 2. — The proportionate quantities absorbed during the 

 fusion of different solids are measured not by equal weights, but 

 by weights which are proportional to the atomic weights. 



Cor. 3. — Hence solids fuse gradually, and the temperature 

 remains constant during fusion. 



Cor. 4. — Hence the temperature of a solid cannot be elevated 

 above a certain point. 



Cor. 5. — Hence the reason of the operation of that class of 

 frigorific mixtures which depends upon the solution of crystals 

 of saline matter. 



Prop. V. 



Some bodies expand, others contract, during fusion. 



Let A, B, C, D, be four particles of a solid ; join their centres, 



