59 G Intelligence and Miscellaneous Articles. 



0*264 c.c. of liquid per gramme of powder. The moistening of the 

 precipitate of carbonate of calcium with the same liquid caused 

 a rise in temperature of 0°-58 C, the powder absorbing 1-563 c.c. 

 of acetic ether per gramme of powder. The precipitated silica, 

 moistened with the same liquid, rose in temperature 31°-40 C, 

 absorbing 1*67 c.c. per gramme. Experimenting with benzine, I 

 found that the precipitate of carbonate of calcium absorbed 1-61 c.c. 

 per gramme of powder, rising in temperature 0°'22 C, while the 

 precipitated silica rose in temperature ll c, 2l C, absorbing 1-52 c.c. 

 per gramme. These facts w T ould seem to prove that increase in 

 the area of surface brought in contact with the liquid is not a 

 cause sufficient to explain the marked rise in temperature resulting 

 from the moistening of precipitated silica, animal and vegetable 

 charcoal, and in the case of all those substances which I have 

 denominated as Ju/r/rophiles ; wishing by this appellation to indicate 

 the property that certain powders have of: holding tenaciously a 

 portion of the liquid they absorb. 



The union of the liquid with hygrophile substances might be, 

 to my mind, a physico-chemical phenomenon analogous to those 

 cited by van Bemmelen in his researches upon hydrates of unstable 

 composition, that are formed by exposing silica to more or less 

 humid air*. 



My own recent researches in reference to the phenomena of 

 hygrophile powders placed in contact with alcoholic mixtures and 

 diluted acidsf seem to confirm my hypothesis. A non-hygrophile 

 powder, for instance, like quartz or powdered marble, well dried 

 and then placed in contact with an alcoholic mixture (three parts 

 alcohol and one part water), will not alter in any sensible; degree 

 the alcoholicity of the mixture ; while with silica or animal charcoal, 

 well dried, a part of the water is subtracted from the mixture: and 

 silica, well dried, is capable of subtracting water from a diluted 

 solution of sulphuric acid. From this it can be deduced that the 

 behaviour of hygrophile powders produces results that are due to 

 a more energetic action than a simple mechanical one, which would 

 be sufficient to explain the phenomena manifested in the case of 

 non-hygrophile powders that are moistened with liquids without, 

 however, tenaciously holding any portion of then. For this 

 reason, I hold that the heat evolved from hygrophile powders may 

 be produced from a decrease in the specific heat of that part of the 

 liquid tenaciously held by the powders; because this part of the liquid 

 will have lost its quality as a fluid, and assumed a state of solidity 

 or quasi solidity ; for this reason I compare the Pouilht effect, in 

 the case of hygrophile powders, to a species of inverted solution. 



I may add that if the values found by Parks are inferior to my 

 own and those found by Bellati, this difference is due to a 

 change taking place in the silica at a high temperature, as has been 

 noted by Bellati i in reference to the experiments of Linebarger. 



Venezia, February 1903. 



Arc/ures Nccrlandaises de Sciences e.vactes et naturclles, t. xv. p. 321. 

 Harlem, 18*0. 



t AttidelR. Isiiiuto Veneto, t. lxi. parte seconda, p. 647, giugno 1002. 

 | Afti del It. Istituto Veneto y t. lxi. parte seconda, p. 510. 



