Mr. Graham on the Heat disengaged in Combinations. 417 



acid, and the further combination of that oxalate of potash 

 with 3 equivalents of oxalate of water. This rise of tempera- 

 ture is nearly the same as that in the formation of neutral 

 oxalate of potash, namely 10 o, 48. 



To observe the heat disengaged on neutralizing quadroxa- 

 late of potash by hydrate of potash, one-sixth of an equivalent 

 of that acid salt in solution was mixed with three-sixths of an 

 equivalent, or rather more, of the alkali, so as to form neutral 

 oxalate: — 



Before mixture . . 64°-19 64°-20 64°-51 

 After mixture . . . 69°-38 69°-42 69°-71 

 Rise of temperature . 5°'19 5°-22 5°-20 



Doubling 5°*20, the mean result, we have 10 o, 40 F. as the 

 heat disengaged on saturating 1 equivalent of potash by each 

 of the 3 atoms of oxalate of water in the quadroxalate of 

 potash, 



0'192 equivalent (30*70 grains) of quadroxalate of potash 

 was dissolved in 1540 grains of water at 63°, with a fall of 

 2°-02, 2°-13, 2°-14; of which the mean is 2°-10F. This gives 

 by calculation a fall of 10 o, 93 for the solution of a whole equi- 

 valent of quadroxalate of potash, which is o, 88 less than the 

 fall of its constituent salts dissolved separately, 2°*66 with three 

 times 3 o, 05 amounting to 11°\81. 



The different oxalates enumerated appear to absorb quan- 

 tities of heat, on dissolving, which have a simple relation to 

 each other. Thus, dividing the different falls of temperature 

 by o, 88, a number which has more than once presented 

 itself in the discussion of these experiments, we obtain a set of 

 ratios given in the second column ; and which, being multi- 

 plied by two in the third column, approach nearly to round 

 numbers : — 



Cr. oxalate of potash . . 

 Cr. oxalic acid .... 

 Cr. binoxalate of potash . 

 Cr. quadroxalate of potash 



VI. Neutralization of Bicarbonate of Potash with Hydrate of 



Potash. 

 Half an equivalent of the crystallized salt, 31*38 grains, 

 dissolved in water, was neutralized with hydrate of potash: — 



Before mixture . . 67°'28 67°"93 67°*68 



After mixture . . . 70 o, 66 71 0, 24 71 0, 03 



Rise of temperature . 3°*38 3°*31 3°-35 



Phil. Mag. S. 3. Vol. 24. No. 161. June 1844. 2 E 



