Absorbed on contact of Liquid with Solid. 



247 



unreliable. In several experiments, there was a slight crack 

 in the bulb before it was placed in the calorimeter, and in these 

 instances the result obtained was far too low, though the crack 

 was not large enough to admit any visible quantity of water ; 

 this shows the great importance of keeping the powder dry 

 until the moment of the experiment. Other experiments were 

 rejected because there was a rapid variation in the temperature 

 of the room at the time, so that the final temperature of the 

 calorimeter did not reach a constant value until long- after the 

 time usually occupied in making an experiment. The rise of 

 temperature observed in the experiments with sand and cotton 

 silicate was only about -^q° C, and hence the results are only 

 o-iven to the second sionificant figure. 



Table I. 



c 







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hiding 



f calo- 



bulb, 



stirrer. 



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X 



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Mature of 

 Substance. 



5 



u 



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£ 







83 . 

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 © 



a 



as 



3 



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_6 



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O 



GO 



CD 

 03 



-_*• 



£2 , t-, T3 



| t 2 £ 



c* - £ 



I S ~ 



© © £ 







s- 

 3 



It 



| 



© 

 Eh ^ 



© 



| 



£ 



© 





 © 



CQ 



© 



£ 

 £ 



II 



S 

 Is m 



£ 

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GQ 



U 

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CO © 



© ,es 



3 



"c3 M 



1 

 l. 





ft 



H 



§ 



£ 



3 





£ 







O 



Silica 



























(precipitated) 



00025 



10900 



3749 



334 



205-51 



6334 



•208 



11-4 



00105 



2 



11 ;• 



., 





3-563 



355 



210-31 



6*552 



•192 



11-3 



00104 



3'. 





,, 



>> 



4-169 



361 



210-05 



7-012 



•222 



11-2 



00103 



4. 





„ 



>> 



4-037 



353 



239-74 



7-586 



•194 



11-5 



•00105 



5* 



>• M 



•00O40 



6820 



3-940 



403 



207-26 



7-320 



•136 



715 



00105 



6. 



Sand 



010 



231 



20050 



3-70 



220 03 



5-400 



•022 



•24 



0010 



7. 



,, 



., 



,, 



20-589 



4-57 



240-10 



5-482 



•020 



•23 



•0010 



8. 



j. 



,, 



„ - 



22-033 



3-81 



252-28 



8-320 



•020 



•23 



•0010 



9. 





?i 



., 



20-188 



414 



25515 



9-228 



•018 



•23 



•0010 : 



10. 



Silicate 



(cylindrical 























filaments) 



•00175 



847 



2-240 



3-81 



200-10 



5-742 



010 



•89 



•0011 ! 



11. 



>. 



!t 





4 006 



3-50 



210-93 



5722 



•018 



•95 



•0011 



12. 



•' 



" 



" 



4-138 



3-47 



211-75 



6052 



•018 



•92 



•0011 : 



* See Table II. for results of other experiments with silica. 



It is considered that these results justify the enunciation of 

 the following law : — 



" When silica, sand, or glass, is brought in contact with water, 

 at approximately constant temperature, the heat evolved is pro- 

 portional to the area of the surface exposed by the solid, 

 and the amount of heat developed per square centimetre is 

 approximately '00105 calorie when the temperature is near 7° C 



