Caloric equivalents of some plant and animal material : The importance of acid corrections and comparison of precision between the Gentry-Wiegert micro and the Parr semi-micro bomb calorimeters.

Orthogonal regression equations of caloric density on the time of collection are given for several materials of ecological interest. Ninety five percent of replicate samples were within ±1% of the mean cal g-1 using a Parr adiabatic semi-micro bomb calorimeter, while agreement was 2.8% using the Gentry-Wiegert bomb calorimeter. Weight specific acid corrections for low ash content biotic material decrease with increasing sample weight. The acid correction is more important using the Parr calorimeter (equal to 20-30% of the technique variation) than with the Gentry-Wiegert bomb (equal to 10-20% of the technique variation).