208 Mr. Herapath on True Temperature, and the [Se1>t. : 



the figures of the particles are similar, the ratio of their diame- 

 ters becomes known, which is the subtriplicate of the ratio of the 

 magnitudes. 



It is to be observed that it is not necessary for the equality of 

 the ratios of the magnitudes and masses of the particles, that the 

 particles be composed of similar atoms similarly arranged ; it is 

 enough if the quantity of solid matter to the quantity of pores 

 in each particle has the same ratio. 



Scholium. 



Mercury, according to the best experiments I can meet with, 

 has a specific gravity about 13-6 times greater than that of dis- 

 tilled water ; therefore, the mass of a particle of mercury is to 

 the mass of a particle of water, supposing both homogeneous 

 fluids, and that the experiments related by Dr. Henry are right, 

 in a ratio compounded of that of 1 to 13*5, and that of 1 to 2, or 

 in a ratio equal to that of 1 to 27. A particle of mercury con- 

 sequently contains 27 times more solid matter than a particle of 

 water ; and, if the conditions in the preceding corollary are ful- 

 filled, is 27 times greater in magnitude, and three times greater 

 in diameter, which agrees with what I have stated p. 406 of the 

 last volume of the Annals. 



That water has really more particles in a given space than 

 mercury, and that it is to this its supposed superior capacity for 

 heat is owing, may be made evident from our principles in a 

 general way thus. Water and mercury mixed in equal volumes 

 always produce a temperature nearer to that of the water than to 

 the temperature of mercury. But by our theory of heat the 

 temperature of a body is measured by the intensity of the motion 

 or vibration of one of its particles. When, therefore, portions 

 of two bodies at unequal temperatures are mixed together, the 

 temperature or mean motion of a particle of the mixture will 

 deviate less from the temperature or individual mean motion of 

 the greater number of particles than from that of the less ; and 

 consequently when equal volumes of two bodies are mixed that 

 body will have the greatest number of particles from whose tem- 

 perature the temperature of the mixture deviates the least. 

 Hence, therefore, water has a greater number of particles than 

 mercury. 



Now if mercury has a less numeratom than water, and the 

 specific gravity of mercury be greater than that of water, the 

 mass of a particle of mercury must exceed that of a particle of 

 water. 



This last inference might be demonstrated in a different way 

 by other principles, which will at the same time presents us with 

 an elegant and a beautiful illustration of the coincidence and 

 agreement of apparently the most independent and unconnected 

 parts of our general theory of the universe. I shall at present 

 merely touch on the subject in a general way, and shall not stop 



