THE COPLEY MEDALIST OF 18rl 457 



by the combustion of the tree. The heat and work poten- 

 tial in our coal strata are so much strength withdrawn 

 from the sun of former ages. Mayer lays the axe to the 

 root of the notions regarding " vital force," which were 

 prevalent when he wrote. With the plain fact before us 

 that in the absence of the solar rays plants cannot per- 

 form, the work of reduction, or generate chemical tensions, 

 it is, he contends, incredible that these tensions should be 

 caused by the mystic play of the vital force. Such a hy- 

 pothesis would cut off all investigation ; it would land us in 

 a chaos of unbridled fantasy. "I count," he says, " there- 

 fore, upon your agreement with me when I state, as an 

 axiomatic truth, that during vital processes the conversion 

 only, and never the creation of matter or force occurs." 



Having cleared his way through the vegetable world, 

 as he had previously done through inorganic nature, 

 Mayer passes on to the other organic kingdom. The 

 physical forces collected by plants become the property 

 of animals. Animals consume vegetables, and cause them 

 to reunite with the atmospheric oxygen. Animal heat is 

 thus produced; and not only animal heat, but animal mo- 

 tion. There is no indistinctness about Mayer here; he 

 grasps his subject in all its details, and reduces to figures 

 the concomitants of muscular action. A bowler who im- 

 parts to an 8-lb. ball a velocity of 30 feet, consumes in 

 the act TTF of a grain of carbon. A man weighing 150 

 Ibs., who lifts his own body to a height of 8 feet, con- 

 sumes in the act 1 grain of carbon. In climbing a moun- 

 tain 10,000 feet high, the consumption of the same man 

 would be 2 oz. 4 drs. 50 grs. of carbon. Boussingault 

 had determined experimentally the addition to be made 



to the food of horses when actively working, and Liebig 



SCIENCE 20 



