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



is wholly repulsive; at I evanescent; beyond I repulsive in 

 infinitum. If the heat be increased by the smallest possible 

 quantity, the particles must separate until the force of repulsion 

 is balanced by some external force. Q. E. D. 



Cor. 1. — Under the pressure of the atmosphere or any other 

 external compression, a liquid will become gaseous at a higher 

 temperature than in vacuo. 



Cor. 2. — The greater this pressure is, the higher will be the 

 temperature required. 



Cor. 3. — Some bodies may become gaseous, without previously 

 entering into a state of fusion; for H and K may coincide before 

 cohesion is destroyed. 



Cor. 4. — Such bodies may be fused under a strong pressure. 



Cor. 5. — A liquid boils in vacuo, when H and K coincide. 



Cor. 6. — Under pressure, at the point M, the boiling point is 

 attained when the repulsive force exceeds the centripetal by a 

 quantity equal to the compressing force. 



Cor. 7. — The temperature of a boiling liquid is the same as 

 that of the disengaged vapour. 



Prop. II. 



Caloric is absorbed during evaporation. 



From the ratio between the specific gravities of the same 

 body in a solid or liquid, and in a gaseous state, it is evident 

 that in the latter, the particles are separated to a great distance 

 from each other; therefore their calorific atmospheres are 

 enlarged, and heat is absorbed. Q. E. D. 



Cor. 1 . — The specific heat of any body is greater when it is 

 elastic, than when in a solid or liquid state. 



Q or% 2. — Hence the action of frigorific processes which depend 

 upon evaporation. 



(j or . 3, — Heat will be evolved when a gas is resolved into a 

 liquid or solid state. 



Prop. III. 



At a given temperature, the elastic force of a gas will be nearly 

 Inversely as its volume. 



By Lemma 1 , Sect. 3, the elas- 

 tic force of a particle of a gas is 

 inversely as the distance from its 

 surface ; therefore, neglecting the 

 force with which the particles at- 

 tract each other, the elastic force 

 of a gas will be inversely as its 

 volume ; for let A, B, C, D, &c. 

 be a number of particles of a gas, 

 they are equal and at all equal 

 distances, their forces are equal, 

 by the hypothesis. Bisect the 

 distance F G ia H, and join D H ; then, since F H is equal to 



