THE EEASON WHY. 



For ruy days are consumed like smoke, and my bones are burned as an 

 hearth." PSALM en. 



87. What is animal heat ? 



Animal heat is derived from the slow combustion of carbon in the 

 blood of animals with the oxygen of the air which the animals 

 breathe. 



88. What is latent heat ? & %;-, 



Latent heat (or more properly latent caloric) is that which 

 exists, in some degree, in all bodies, though it may be imperceptible 

 to the senses. 



89. Is there latent caloric in ice, snow, water, marble, Sfc ? 

 Yes ; there is some amount of caloric in all substances. 



[A blacksmith may hammer a small piece of iron until it becomes red hot. 

 With this he may light a match, and kindle the fire of his forge. The iron has 

 become more dense by the hammering, and it cannot again be heated to the 

 same degree by similar means, until it has been exposed in fire, to a red heat. 

 Is it not possible that, by hammering, the particles of iron have been driven 

 closer together, and the latent heat driven out ? No further hammering will 

 force the atoms nearer, and therefore no further heat can be developed. But 

 when the iron has again absorbed caloric, by being plunged in a fire, it is again 

 charged with latent heat. Indians produce sparks by rubbing together two 

 pieces of wood. Two pieces of ice may be rubbed together until sufficient 

 warmth is developed to melt them both. The axles of railway carriages 

 frequently become red hot from friction.'] 



90. Have vegetables heat ? 



Yes ; whenever oxygen combines with carbon to form carbonic 

 acid gas, an extrication of heat takes place, however minute the 

 amount. Such a combination occurs much more extensively during 

 the germination of seeds and the impregnation of flowers, than at 

 any other time. In the germination of barley heaped in rooms, 

 previous to being converted into malt, it is well known that a 

 considerable amount of heat is developed. 



91. Has any investigation of this subject ever been care- 

 fully made ? 



Yes. Lamarck, Senebier, and De Candolle, found the flowers of 

 the Arum Maculatum, between three and seven o'clock in the 

 afternoon, as much as 7 deg. Eeaum. warmer than the external 

 air. Schultz found a difference of 4 deg. to 5 deg. between the 

 heat of the spathe of the Canadian pinnatifolium and the sur- 



