An Investigation of a Case of gradual Chemical Change. 411 



Moreover, the addition of the potassium chloride appears to have 

 no such disturbing effect as would result if potassium chlorate was 

 formed to some extent as soon as the potassium chloride was added, 

 and a condition of saline equilibrium between four substances 

 resulted. In the first series in the above table the mixture in its last 

 stage corresponded exactly to a mixture of potassium chlorate 

 (6 x 51~5 millionth-gram-molecules) and hydrochloric acid (13 X 65'11) 

 supposing that complete double decomposition had taken place. For 

 comparison, therefore, a mixture was made containing initially these 

 amounts of potassium chlorate and hydrochloric acid with this 

 result: 



Rate obtained = 0*00337. 



Rate in table = 0-00333. 



This result might, of course, be taken merely to mean that the same 

 state of saline equilibrium had been attained in both cases, but it has 

 been already pointed out that the effect of progressive additions of 

 potassium chloride, giving a result expressible by a formula like the 

 above, is to show that it remains an unaltered substance in the 

 mixture. 



In the experiment detailed below, the salt was added to a mixture 

 made with potassium chlorate and hydrochloric acid, and therefore it 

 is presumed that it contained already some potassium chloride, 

 obtained by saline decomposition. The results then obtained were of 

 the same nature as before : 



Table YIL 



It will be seen that the salt added continues to have its specific 

 accelerative effect, and though at the end the whole quantity of 

 potassium chloride present was 8 X 5" 15 millionth-gram-molecules, 

 there is no sign whatever of the saline equilibrium "being upset. The 

 quantity of hydrochloric acid present is about double this (16 X 63* 11 

 -2x51-5), 



In all these experiments, the highest precision in adding the 

 potassium chloride was not possible, as it was necessary to add the 

 solid salt to a liquid of standard volume, and a slight variation of the 

 conditions of the experiment besides the one contemplated was thus 

 inevitable. 



VOL. XLV. 2 B 



