378 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



heat the apparatus, the quantity of water, the rise in temperature, 

 and the loss of heat by radiation, the amount of heat produced 

 by the known weight of substance may be ascertained. Urine is 



Fig. 82. Calorimeter (Atwater and Hempel) in which the substance 

 is burned in compressed oxygen. 



either evaporated in a vacuum directly, or absorbed in paper of 

 known heat value, and then dried. Heat measurements are made 

 very often in investigations of animal nutrition. 1 



1 For discussion of heat values of nutrients, see Stohinann, Exp. Sta. 

 Record No. 6, p. 590. 



