As one of the fundamental researches for the development of microexploxion lithotripsy, we measured the water absorption rate and the weight decrease rate in dryness on 8 urinary calculi. And on other 8 urinary calculi, we also measured the compressive strength and the modulus of elasticity in both dry and wet conditions. The results were as follows:
1) The water absorption rate was from 1.3 to 21.0%.
2) The weight decrease rate in dryness was from 3.4 to 19.2%.
3) The compressive strength was, from 11 to 61kg/cm2 in dry condition, from 6.6 to 36kg/cm2 in wet condition. The ratio wet to dry condition was from 0.32 to 1.04 (mean 0.67±0.26).
4) The modulus of elasticity was, from 11.5×108 dyne/cm2 to 47.8×108 dyne/cm2 in dry condition, from 3.8×108 dyne/cm2 to 23.6×108 dyne/cm2 in wet condition. The ratio wet to dry condition was from 0.26 to 1.10 (mean 0.66±.030).
5) When a calculus model for destruction test is prepared, ti may not be necessary to take the layer formation of calculus into consideration. The strength of the model in the wet condition should be similar to, or slightly lower than the value estimated in the former report.
