MM. Jamin and E-ichard on the Laws of Cooling. 4d7 



healthy lungs to 165 in pulmonary tubercular growth, partly 

 softening, partly consolidated. 



15th. That there is apparently no increase of fat in tubercular 

 pulmonary tissue, there being a mean of 4*28 of fat in 200 

 grammes of healthy lungs, and 3 '91 in a similar weight of the 

 diseased tissue ; but as there is a little more water in the diseased 

 than healthy lungs, it follows that a given weight of tubercular 

 matter from the lungs apparently contains, proportionally to its 

 dry residue, a little more fat than healthy pulmonary tissue under 

 a similar circumstance. 



16th. That in nature soluble matter is undergoing a per- 

 petual transformation — taking place, in rotation, from the crys- 

 talloid into the colloid condition, and from the colloid into the 

 crystalloid condition. Animal secretions and the products of 

 decomposition of animal and vegetable tissues are crystalloid, 

 admitting of their ready distribution through land and water by 

 a physical process of diffusion. These crystalloid substances are 

 transformed into colloids by plants and used in that form as 

 food for animals ; and both plants and animals yield them back 

 again in their original crystalloid condition. Chloride of sodium 

 alone appears to be an exception to this rule. 



LI V. On the Laws of Cooling. 

 By MM. Jamin and Kichard*. 



Part II. Cooling Power ofGasesf. 



AT the meeting of the 15th July last we announced to the 

 Academy that a gas heated to 6 + S6 in an enclosure the 

 walls of which are at 6° cools regularly, and loses during each 

 unit of time a quantity of heat expressed by the law which Du- 

 long and Petit found for solid bodies^ and which is 



S expressing the surface of the enclosure, and K a coefficient 

 depending on the gas. 



We shall now inquire what is the heat which a gaseous mass 

 takes away, by its contact, from a heated solid placed in its 

 centre. The apparatus remains the same. It is a large balloon 

 of glass immersed in a trough filled with water continually agi- 

 tated by a current of air, and kept at a sensibly constant tempe- 

 rature 6. The initial pressure H is given by a mercury mano- 

 meter, and the increments of pressure A by a water manometer. 



* Translated from the Comptes Rendus de VAcademie des Sciences, 18/2, 

 No. 8, pp. 453-458. 



t For Part I. see the Philosophical Magazine, October 1872, p. 244. 



