Eq. 3
Where is the daily water loss, C is a conversion constant
(155.52*107/R*T, where R is the ideal gas
constant:6.24*104cm3*Torr/mol*°K, and T is absolute temperature in °K),
is the diffusion coefficient of water in air at a given temperature (in
°C), Ap/L is porosity, and the difference in pressure across the
eggshell. From this using equation 3.5 water vapour conductance of whole
eggs at 25 and 0% humidity was calculated and compared with the results
reported by Calder (1978) and Silyn‐Roberts (1983) for Brown Kiwi, and
with the values reported by Ar et al. (1974) for other avian species.
The water vapour conductance was calculated by using the daily water
loss calculated from equation (3) in equation (1). Finally, to compare
our results with allometric predictions we calculated the water vapour
conductance for those eggs based on Ar et al. (1974):
\(G_{H_{2}\text{O\ \ }}=0.432*W^{0.780}\) Eq. 4
Where W is the fresh weight of the egg, in this case we used the arrival
weight of the eggs since there was no way to know the fresh egg weight.
In this measurement only Brown Kiwi eggs were used as were the only ones
that were weighed before hatching so the water loss could be determined.