330 



Intelligence and Miscellaneous Articles. 



calorimeter made of thin sheet brass, consisting of two cylindrical 

 tubes, one within the other, having a common axis. The base of 

 the internal tube was perforated to allow the escape of air, when 

 pouring the liquid upon the powder with which the tube was 

 filled. A flannel disk placed at the base prevented the escape of 

 the powder. 



The powder was thoroughly dried before being poured into the 

 internal tube, which was closed at the top with an indiarubber 

 stopper, and suspended by three silk threads, within a vessel con- 

 taining chloride of calcium. The external tube contained distilled 

 water into which was immersed a delicate thermometer. 



Calories developed by Charcoal moistened with Distilled Water. 



Weight of the 

 Charcoal. 



Volume of the 

 Water. 



Calories, !<*?££■* 



44 gr. 



40 



40 



35 



30 



60 cm. 3 



53 



58 



51 



43 



629-00 14-29 

 569-80 14-25 

 573-30 14-33 

 514-30 14-69 

 440-30 14-67 



Calories developed by Silica moistened with Distilled Water. 



Weight of the 



Volume of the 



Calories-gr. 



Calories by 1 gr. 



Silica. 



Water. 



developed. 



of powder. 



50 gr. 



72 cm. 3 



677-10 



13-54 



50 



70 



684-50 



1369 



45 



63 



603-10 



13-40 



40 



60 



558-70 



13-97 



40 



62 



558-70 



13-97 



40 



66 



555-00 



13-87 



35 



53 



477-30 



13-64 



Meissner, in his experiments *, did not use a fixed weight of 

 water ; at one time he would use a quantity of water equal in 

 weight to the powder, at another time a quantity double, and at 

 times much less. In my own case, however, I always used that 

 quantity of liquid which I found would be absorbed, by capillarity, 

 by a quantity of charcoal or silica equal to that contained in the 

 calorimeter. Had I poured on the powder a smaller amount of 

 water, parts would have remained umnoistened ; a larger quantity 

 would have absorbed a part of the heat generated. 



The foregoing results may be of interest, not only to physicists 

 in general, but to students of geothermic phenomena. In fact, 

 the reader will find in my original pamphlet an account of certain 

 experiments in which silica, moistened with a proportionate 

 quantity of water, rose from an initial temperature of 19° to that 

 of 70°. 



Venice, June 1898. 

 * " Ueber diebeiin Benetzen purverfbrniiger Korper auftretecde Warme 

 tonung." Wiedemann's Annalen, xix. (1886). 



