812 Dr. G. Gore on Changes of Temperature caused 



" Decomposition of Liquids by Contact with Powdered Silica" 

 Proc. Birm. Phil. Soc. 1894, vol. ix. pp. 1-24) ; and it was 

 not rendered alkaline to test-paper. 



Various Powders with Water and Ammonia. 

 Table III,— With Water. 



Exp. 





Grains. C. Deg. 



Exp. 





Grains. 



O.Deg. 



82. 

 83. 

 84. 

 85. 

 86. 

 87. 



BaS0 4 , , 

 SrC0 3 , 

 OaCOg 

 PbO 



300 

 200 

 100 

 400 

 50 

 200 



•00 

 •05 

 •05 

 •08 

 •10 

 •10 



88. 

 89. 

 90. 

 91. 

 92. 



MgCOg 



Fe 2 3 



Sn0 2 



100 

 150 

 200 

 300 

 200 



•11 

 •12 



•18 



•47 



1-16 



Mn0 2 



ALOo 



0r 2 O 3 



BaC0 3 



2 t> 



Table IV — 



With 10 per 



cent. 



Aqueous A 



mmoni 



a. 



Exp. 





Grains. 



C.Deg. 



Exp. 



99. 

 100, 

 101. 

 102. 

 103. 





Grains. 



C.Deg. 



93. 

 94. 

 95. 

 96. 

 97. 

 98. 



CaCOg 



SrCOg 



BaCOg ,... 

 BaS0 4 



MgCOg 



Fe 2 3 



100 

 200 

 200 

 300 

 100 

 150 



•06 

 •08 

 •10 

 •15 

 •17 

 •18 



Sn0 2 



200 

 50 

 400 

 300 

 200 



•22 

 •52 

 •53 

 •90 

 1-64 



Or„Oo 



PbO 



Mn0 2 

 Mn0 3 





The volume of liquid in each case was 50 centim. Washing 

 the barium sulphate with a 10-per-cent. solution of ammonia, 

 then with water, and finally heating to redness, hardened it. 

 In the above experiment (No. 96) it was not washed with 

 ammonia. 



General Remarks and Conclusions. 



It is evident, that as in all cases the formation of a liquid 

 film upon the surfaces of the solid particles must have been 

 attended by the destruction of an air-film, and the latter 

 action was probably accompanied by absorption of heat 

 (different in amount with different powders), the observed 

 rise of temperature did not represent the whole of the heat 

 evolved by contact of the liquid and solid. Consequently it 

 is possible that in those cases in which little or no rise of 

 temperature was observed, the amount of heat absorbed by 

 the liberated air may have been equal to that evolved by the 

 uniting liquid. 



