497 



ter placed under the tongue, is rather above than below that of per- 

 sons of middle age ; and this he thinks may be explained by the cir- 

 cumstance, that most of the food used by old persons is expended in 

 administering to the function of respiration. 



In the third section, on the influence of air of different tempera- 

 tures on animal heat, after alluding to what he had witnessed of the 

 rise and fall of the temperature of man on entering the tropics, and, 

 within the tropics, on descending from a cool mountainous region to 

 a low hot country, he adduces certain observations to show that in 

 this country similar changes of temperature take place in a few 

 hours in breathing the air of buildings artificially heated ; and, in 

 confirmation, he describes the results of many observations made on 

 an individual in the very variable climate of Constantinople, where, 

 between March and July, in 1841, the thermometer ranged from 



In the fourth section, he describes the observations which he made 

 to determine the effect of moderate exercise, such as that of walk- 

 ing, on the temperature of the body, tending to prove, that while it 

 promotes the diffusion of temperature and produces its exaltati^)n in 

 the extremities, it augments very little, if at all, the heat of the cen- 

 tral and deep-seated parts. 



A paper was also in part read, entitled, " On the Thermal Changes 

 accompanying Basic Substitutions." By Thomas Andrews, M.D., 

 M.R.I. A., Professor of Chemistry in the Royal Belfast Institution. 

 Communicated by M. Faraday, Esq., D.C.L., F.R.S., &c. 



The author gives an account of a series of experiments which he 

 made on the heat evolved during the mutual reaction of acids and 

 bases upon one another, from which he draws the general conclusion 

 that when the influence of all extraneous circumstances is eliminated 

 from the result, the change of temperature is determined by the na- 

 ture of the base, and not by the acid element of the combination. 

 Hence he deduces the general law that, when one base displaces 

 another from any of its neutral combinations with an acid, the heat 

 evolved or abstracted is always the same, whatever the acid element 

 may be, provided the bases are the same. The base employed in 

 the first set of experiments for displacing others was the hydrate of 

 potash in a state of dilute solution of known strength; this was 

 rapidly mixed, in a suitable apparatus, with an equivalent solution 

 of the salt to be decomposed ; the change of temperature which re- 

 sulted was accurately determined, and the due corrections for the 

 influence of the vessels and the specific heats of the solutions and of 

 the precipitates produced, were applied. The experimental results 

 are stated in various tables, from which it appears that the changes 

 of temperature, referred to 1000 parts of water, were, with salts of 



31° to 94°. 



o 



o 



Lime . . 

 Magnesia 

 Barytes . 

 Strontia . 



from 



()-33 

 0-10 

 0- 



to 



- 0-38 



- 0-15 



0- 

 0- 



