, t ) ^(v,t)\ } , the latent heat with respect to volume, belongs to classical calorimetry. it accounts for the occurrence of energy transfer by work in a process in which heat is also transferred; the quantity, however, was considered before the relation between heat and work transfers was clarified by the invention of thermodynamics. in the light of thermodynamics, the classical calorimetric quantity is revealed as being tightly linked to the calorimetric material's equation of state p = p ( v , t ) . provided that the temperature t is measured in the thermodynamic absolute scale, the relation is expressed in the formula c t ( v ) ( v , t ) = t ∂ p ∂ t | ( v , t ) ^(v,t)=t\left.\right|_\ } . difference of specific heats advanced thermodynamics provides the relation c p ( p , t ) − c v ( v , t ) = [ p ( v , t ) + ∂ u ∂ v | ( v , t ) ] ∂ v ∂ t | ( p , t ) (p,t)-c_(v,t)=\left\,\left.\right|_ . from this, further mathematical and thermodynamic reasoning leads to another relation between classical calorimetric quantities. the difference of specific heats is given by c p ( p , t ) − c v ( v , t ) = t v β p 2 ( t , p ) κ t ( t , p ) (p,t)-c_(v,t)=^(t,p)}(t,p)}}} . practical constant-volume calorimetry (bomb calorimetry) for thermodynamic studies constant-volume calorimetry is calorimetry performed at a constant volume. this involves the use of a constant-volume calorimeter. no work is performed in constant-volume calorimetry, so the heat measured equals the change in internal energy of the system. the heat capacity at constant volume is assumed to be independent of temperature. heat is measured by the principle of calorimetry. q = c v δ t = δ u , \delta t=\delta u\,,} where δu is change in internal energy, δt is change in temperature and cv is the heat capacity at constant volume. in constant-volume calorimetry the pressure is not held constant. if there is a pressure difference between initial and final states, the heat measured needs adjustment to provide the enthalpy change. one then has δ h = δ u + δ ( p v ) = δ u + v δ p , where δh is change in enthalpy and v is the unchanging volume of the sample chamber.