34 On the Relation of the Specific [July 



placed nearer to the prism than k Z, it assumes different 

 appearances at different distances ; at rf e, for instance, it 

 has a white centre, fringed at its upper edge with blue and 

 violet, and at its lower edge with yellow and red ; at f g 

 the white light disappears, and the spectrum is then formed 

 of four colours, red, yellow, blue, and violet. At A i it has 

 a green centre, which increases the number of colours to 

 five; and at k Z, when fully developed, it is reduced to 

 three, red, grean, and violet. 



Fig. 2. represents a front view of the spectrum, when 

 the screen is placed atcZe; and it also represents the super- 

 position of the three cards with which the subject has been 

 before illustrated ; the red card extends in breadth from 

 r to r, the green card from g to g, and the violet card from 

 V to n. P. C. 



Weston Super Mare, 

 May 2lst 1835. 

 To the Editor of the Records of General Science, 



Article VI. 



On the Relation of the Specific Heat of Bodies to their 

 Atomic Weights. 



This paper is intended to convey a condensed view of the 



researches of Avogrado, an Italian philosopher, as related 



in two separate memoirs.* 



It may be proper to observe that in a previous paper,t 



from the consideration of the affinity between the density 



and specific heat of bodies, he had established the formula 



7n 

 rf = — 3 where the density of the ductile metals, is simply 



proportional to the mass of the atom divided by the cube of 

 its affinity for heat, or affinitary number as it may be termed ; 

 a represents the quantity which corresponds with the cube 

 of the distance of the centres of the atoms, that is to say, 

 this distance is simply proportional to the affinity of each 

 substance for heat, the mass of the atom not entering into 

 its determination. 



♦ Ann de Chiin. et de Physique, t. Iv. and Ivii. 



t Memorie delln Reale Accaderaia delle Scieuze di Torino, xxx. 91, 



