Animal Heat. 33 



To those who have studied chemistry, even but 

 a little, the rapid development of heat unbear- 

 able in water previously cold is familiar. It is 

 a good illustration for our purpose. 



A quantity of cold water is taken in a tumbler 

 or other thin glass vessel, and held in the hand, 

 taking care to grasp that part in contact with the 

 water. Sulphuric acid (oil of vitriol) is then 

 added in nearly equal quantity, when by chemical 

 action, which immediately takes place between 

 the acid and water, intense heat is developed, 

 rendering it an impossibility to hold the vessel in 

 the manner adopted at the commencement. 



The rubbing together of certain substances, or 

 beating of metals upon hard surfaces, also pro- 

 duces great heat. Here the molecular disturb- 

 ance or the alteration of position of the ulti- 

 mate particles composing the mass which ensues 

 from the concussion may not be unlike that 

 which accompanies chemical action, although the 

 means adopted to bring about each may be 

 different. 



It is, however, an undoubted fact that heat is 

 developed by the chemical union of substances 

 outside the body, and similar conditions are now 

 found to apply to substances which are contained 

 within it. 



There are always met with elements and sub- 

 stances which, in contact with vital organs and 

 their secretions assume the power of union by 

 chemical action. They pervade the whole of the 



