THE TAKING UP OF WATER BY RAW AND SODA-BOILED COTTON AT 20°C

Abstract

Previous work has generally indicated that the moisture content of cotton at a given temperature and humidity depends on the previous condition of the material. In particular, it has frequently been reported that the moisture regain is different according as the cotton is introduced into the atmosphere in the wet or dry condition. Many workers, however, have doubted whether such a difference really exists, or whether the data recorded as evidence have been based on experiments in which final values had not been reached. The present paper describes a prolonged investigation of the subject in which a single determination of moisture content usually took three weeks, and all changes of weight greater than 0.0003 gram were regarded as significant. The results show definitely that there are at least two possible values of the moisture regain for a sample of cotton exposed to an atmosphere of given temperature and humidity, a higher value if the cotton had been initially wetter than the atmosphere, and a lower value if it had been drier. In addition, it is shown that previous heat treatment affects the moisture regain. If cotton is heated at a high temperature (110°C.) it is less able to absorb water vapour. The effect of scouring has also been investigated, and it is shown that soda-boiled cotton takes up considerably less water than raw cotton when placed dry in a moist atmosphere.