90 THE FORMATION OF FAT IS 



carbon had been directly burned. In this form, 

 therefore, the disengagement of heat as a conse- 

 quence of the formation of fat would be undeni- 

 able ; and it could only be considered hypothetical, 

 on the supposition that carbon and oxygen were 

 diseno-aofed from one and the same substance, in the 

 proportions to yield carbonic acid. 



If, for example, we suppose that from 2 atoms 

 of starch, C24H20O20, the elements of 9 equivalents 

 of carbonic acid are separated, there will remain a 

 compound containing, for 15 equivalents of carbon, 

 20 of hydrogen and 2 of oxygen ; for 



C24H20O-J0 = C9O18 + C15H20O2. 

 Or, if we assume that oxygen is separated fi*om 

 starch in the form both of carbonic acid and water, 

 then, after subtracting the elements of 6 equivalents 

 of water and 6 of carbonic acid, there would remain 

 the compound C18H14O2 ; for 



C24H20O00 = C6O12 + HfiOfi + C18H14O2. 



Assuming, then, the separation of oxygen in either 

 of these forms, it remains to be decided whether the 

 carbonic acid and water given off were contained, as 

 such, in the starch, or not. 



If they were ready formed in the starch, the 

 separation might occur without the disengagement 

 of heat ; but if the carbon and hydrogen were pre- 

 sent in any other form in the starch (or in the com- 

 pound from which the fat was produced), it is obvious 

 that a change in the arrangement of the atoms must 

 have occurred, in consequence of which the atoms 



