certain Fibrous Substances when wetted. 373 



verified. Cotton, woollen, and silken materials, and paper are all 

 effective ; and if previously well dried will readily attain in the 

 mouth a temperature of 110° F. and over in less than a minute. 

 But it is not necessary to dry those substances, in order that their 

 temperature may be raised above that of their surroundings, for 

 I have frequently seen the thermometer reach 100° F. or more 

 when simply wrapped in a few turns of my pocket-handkerchief 

 taken directly from the pocket ; and have known it attain 102° F. 

 when enclosed in a strip of linen torn from a towel hanging in 

 the room. I have often repeated the experiment of Dr Parsons, 

 using woollen or cotton materials and paper, and found the tem- 

 perature rise 30° C. or more above that of the steam. The 

 following is a representative experiment. 



A long strip of filter paper was weighed, and then thoroughly 

 dried in hot air, aud weighed again. It was found to have lost no 

 less than 11 per cent, of its weight in the process of drying, 

 although at the start it was in the ordinary sense dry. It was 

 then rolled tightly round the bulb of a thermometer, and sur- 

 rounded by a few more turns of the same kind of paper, making 

 a roll 3 in. by 2^-. Next it was warmed to 96° C. and placed in a 

 current of unconfined steam at 100°. The temperature within 

 the roll rose to 125° C. in 4 minutes, and soon after to 132° C, at 

 which point it remained for some time, and then fell slowly, so 

 that at the end of half-an-hour it was still 128° C. The roll of 

 paper was then taken out of the steam, and its protective cover 

 removed. On weighing it was found to have risen in weight from 

 21*5 to 21 - 8 grms., thus gaining 1*5 percent. Nevertheless it was 

 still very dry and crackled when crumpled. 



A similar experiment was made with asbestos fibre, which had 

 undergone a prolonged washing in distilled water to remove salts. 

 The asbestos was packed into a small cylinder of copper gauze, 

 and heated all night in a gas flame in order to thoroughly dry it. 

 It was then cooled over sulphuric acid, and when its temperature 

 had reached 95° it was put in a current of steam at 100°. The 

 result was very different from that obtained with fibrous materials 

 of an organic kind. The temperature within the asbestos did not 

 exceed that of the steam. 



From this it appears that one has to do with a chemical and 

 not merely a physical action. For though the asbestos fibres may 

 be very different both in size and configuration from those of the 

 other materials used, it is not probable that they would have been 

 entirely inactive had the action in question depended on physical 

 causes. It is therefore probable that there is some form of 

 chemical union between the organic material and water. 



VOL. x. PT. vi. 27 



