The self-heating of wet wool

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Abstract
A study has been made of the tendencies for various grades of wet wool to self-heat under aerated adiabatic conditions, and comparisons made with the behaviour of wet wool in bales. Whereas 76°c is the highest temperature recorded for wet baled wool, it is demonstrated that adequately acrated wet wool can attain temperatures ranging up to 102°c under adiabatic conditions. An automatic apparatus capable of producing these conditions is described. The self-heating of wet wool up to 76°c is normally caused by bacterial metabolism, and it is shewn that some thermophilic bacteria appear to be able to produce temperatures up to at least 79.4°c. Although all these bacteria utilise the wool fibre itself, their metabolic activity is greatly stimulated by the presence of grease, suint, scud, and other materials. When wet wool is kept hot (say 80°c or above) it degrades, and will then react chemically to cause further heating. This chemical heating reaction does not occur when the wool is completely dried. Aerated wool containing water in insufficient amount to saturate the interstitial atmosphere can also heat, probably because of the growth of moulds. All these effects are discussed in relation to the self-heating of other wet organic materials and to the known action of microbiological agencies on wool. The relation of this wet heating to the spontaneous ignition of wool is also discussed.