ABSORPTION OF MOISTURE
At a normal relative humidity of 65 per cent it shall not absorb more than 5 per cent of moisture, or expand (an average of both directions) to exceed 0.45 per cent, and when subjected in a closed case to a saturated atmosphere for two hours at a temperature of 20° C. (68° F.) shall not absorb more than 10 per cent of moisture or expand (an average of both directions) to exceed 2 per cent. All increases to be computed on the basis of the dry weight and dimensions.