408 Dr. A. Tilden. Influence of Temperature [June 18, 



Experiment Approximate Mean heat of 



number. temperature. dissolution. 



26 to 29 22° 6322 



30 „ 33 35—40° 6842 



34 „ 35 40—45° 6769 



36 „ 41 ...... 50—55° 6958 



Calculated from the figure for 22° = 6322, taking = 26*1 (Kopp), 

 18rc+K=1778 (Thomsen), T = 55°. 



Q T =7909, which, is much higher than 7128, the greatest observed 

 value at 55 — 56°. 



For the sake of comparison sulphate of potassium, which always 

 crystallises without water, was taken with the following results : — 



Potassium Sulphate, K 2 S0 4 , in 100 molecules of Water, or 174 parts 

 in 1800 parts by weight. 



Weight of Salt used . . . . 7 733 grams. 

 Weight of Water used . . . . 80 '00 



Specific Heat of Solution K 2 SO 4 .100H 2 O = -8965. 



Number 

 of 

 expt. 



Water 

 equiv. 

 calorim., 

 &c. 



Temperature. 



Correction. 



Total 

 faU. 



Molecular 



heat of 

 dissolution. 



Before 

 solution. 



After 

 solution. 



43 



110-4 



15-23 



13 -015 



- -004 



2-211 



5494 



44 



110-3 



15 02 



13 02 



+ -03 



2-03 



5037 



45 



110-4 



15 -105 



13 -050 



+ -100 



2-155 



5348 



46 



110 3 



15 -70 



13-52 



+ -03 



2-21 



5472 



47 



109-4 



23-665 



21 -560 



- -006 



2-099 



5166 



48 



109 -4 



23-90 



21-78 







2-12 



5219 



49 



109-3 



36-86 



34-93 



- -006 



1-924 



4720 



50 



109 -4 



37-60 



35 53 



- -01 



2-06 



5073 



51 



109 3 



36-99 



35 -00 



- -008 



1-982 



4865 



52 



109 3 



45-00 



43-13 



+ -075 



1-945 



4782 



53 



109-3 



45-06 



43 -20 



+ -046 



1-906 



4678 



Approximate Mean heat of 



temperature. dissolution. 



15° -5338 



24 -5192 



37 -4886 



45 -4730 



Take Q t at 15°= -5338. 



C=34'l (Kopp) and 18n + K=1781 (Marignac). 

 T=45°. 



Q T =-3745. Observed -4730. Difference, 985. 



