54,6 REPORT— 1902. 



reg'ions, and yields carbonic acid to the retr.rnino- venous blood : this carbonic acid 

 (riving the venous blood its darker colour, and being ultimately rejected from the 

 blood and from the body through the lungs, and carried away in the breath. 

 Crawford's very important discovery that the venous blood of a dog which had 

 been kept for some time in a hot-water bath at 112° Fahr. was almost undis- 

 tinguishable from its arterial Idood, proves that it contained much less than the 

 normal amount of carbouic acid, and that it may even have contained no carbonic 

 acid at all. Chemical analysis of the breath in the circumstances would be most 

 interesting ; and it is to be hoped that this cheaiical experiment will be tried 

 on men. It seems indeed, with our present want of experimental know- 

 ledge of animal thermodynamics, and with such knowledge as we have of 

 physical thermodynamics, that the breath of an animal kept for a con.siderable 

 time in a hot-water bath al)OAe the natural temperature of its body may be found 

 to contain no carbonic acid at all. But even this would not explain the r/eneratlon 

 of cold which Dr. Crawford so clearly and pertinaciously pointed out. Very care- 

 ful experimenting ought to be performed to ascertain whether or not there is 

 a surplus of oxgyen in the breath: more oxygen breathed out than taken in. If 

 this is found to be the case, the animal cold would be explained by deoxidation 

 (unburning) of matter within the body. If this matter is wholly or partly water, 

 free hydrogen might be found in the breath ; or the hydrogen of water left by oxygen 

 might be disposed of in the body, in less highly oxygenated compounds than those 

 existing when animal heat is wanted for keeping up the temperature of the body, or 

 when the body is dynamically doing work. 



2. On the Application of the Method of Entropy to Rndiant Energy. 

 By J. Larmor, Sec. U.S. 



The entropy of a material system has been defined by Boltzmann as the 

 logarithm of the probability of its molecular configuration ; and this definition has 

 recently been applied by Planck to the radiation in an enclosure, thereby 

 obtaining a law for the constitution of natural radiation at a given temperature, 

 which is in close accord with the facts. His argument involves simple vibrators 

 in the region, and it is their fortuitous arrangement that enters. It was explained 

 that various diiFiculties attending this procedure are evaded, and the same result 

 attained, by discarding the vibrators and considering the random distribution of 

 the permanent element of the radiation itself, among the differential elements of 

 volume of the enclosure, somewhat on the analogy of the Newtonian corpuscular 

 theory of optics.' 



3. On the Relation of Voltaic Potential Differences to Temperature. 

 By J. Larmor, SecIi.S. 



It was shown, by means of Carnot's principle, that if material substances have 

 no special affinity for electricity, voltaic potential differences should be propor- 

 tional to the absolute temperature. The experiments of Majorana with liquid air 

 as a cooling agent show that they actually fall at a more rapid rate than this law 

 would give, from which it is inferred that imparting an electric charge to a metal 

 involves absorption of heat owing to direct affinity between its molecules and the 

 charge. 



4. Does Motion through the Ether cause Double Refraction ? 

 By Lord Rayleigh, F.R.S. 



5, Report on Electrical Standards. — See Reports, p. 53. 

 ' Cf. Brit. Assoc. RejJort, 1900. 



