An Investigation of a Case of gradual Chemical Change. 413 



We are now in a position to discuss the results obtained in the 

 investigation which Mr. Harconrt originally proposed that we should 

 make, viz., the action of hydrogen chloride on potassium chlorate. 



We shall first discuss the results obtained by varying the hydrogen 

 chloride, keeping the potassium chlorate fixed. The hydrogen 

 chloride varied from v = 20 to v = 10. After the double decom- 

 position mentioned, the amount of acid present is v x 65'11 ux 51*5. 

 As u is constant, the acid varies in arithmetical progression. In the 

 following table u = 3, and thus corresponds to the chloric acid results 

 in Table IY as far as the amounts of acid go, and only differs from 

 it in having present a certain quantity of potassium chloride. It is, 

 therefore, to be expected that the variation will be of the same 

 nature, and this we find to be the case. 



Table IX. 



By inspection it will thus be seen that the third column is not an 

 arithmetical progression. If, however, we treat the series in the 

 other way, we find the second differences of the rate to be approxi- 

 mately constant. Then substituting for the first differences the 

 nearest exact arithmetical progression and re-calculating the rates, 

 we get a series in which the calculated and observed numbers agree 

 fairly well between v = 16 and v = 10, just as in the corresponding 

 chloric acid series given in Table IV (6). 



