THERMAL EQUIVALENTS OF THE OXIDES OF CHLORINE. 195 



•a decomposition that is well known to occur in certain conditions. As- 

 suming this equation to be correct, and employing the following thermal 

 numbers admitted by Pavrc— 



„ KO CIO condensing= 11,436 „ 



we obtain for the formation of an equivalent of aqueous chloric acid 

 — 12,661 heat units. This number is only about one-fifth part of the former 

 number admitted by Favrc. 



There is yet another mode of arriving at the thermal value of cliloric 

 acid. Frankland recently made a series of observations on the heat evolved 

 during the ^oxidation of many organic substances through the action of 

 chlorate of potash, and had necessarily to deduce from the total heat evolved 

 the heat due to the decomposition of the chlorate of potash employed ; his 

 highest result amounts to 5500 heat units evolved per equivalent of chlo- 

 rate of potash decomposed. Now it is easy, from the admitted decomposition 

 and with tlie aid of this result, to calculate the thermal value of chloric 

 acid. 



K0C10.=KCl+0,. 



Formation of KCl ~ . =101,000 



KO = 76,238 



KO with CIO. == 15,187 

 KO CIO, solution = 10,100 



X=-6009. 



101,525 + X + 5.500=101,016. 



The various determinations of the thermal value of chloric acid are inserted 

 in the following Table, along with a reference to the reaction on which the 

 determination is based : — 



Action of chlorine on concentrated caustic potash = — 65,234 (Favre). 

 Condensation of hj'pochlorous acid = — 12,661 (Favre). ^< 



Decomposition of chlorate of potash = — 6,000 (Frankland). 



Action of iodine on chloric acid =—20,500 (Dewar). 



The great difference in these results shows that even with the greatest 

 care experimenters are apt to differ on the intricate subject of thermal values, 

 and that before a satisfactory conclusion can be arrived at-with reference to 

 the true thermal value of chloric acid further experiments ought to be made. 



A series of observations have beeu made on chlorous acid and on the per- 

 oxide of chlorine. 



Chlorous acid was obtained by the action of benzol sulphuric acid on 

 chlorate of potash, and. after washing it was passed directly into water, in 

 order to obtain a dilute solution. . 



The analysis of the solution has invariably differed from that of a 'solution 

 of pure chlorous acid ; and it seems absolutely necessary,' in order to ensure 



02 



