346 OXYGENATED COMPOUNDS OF CHLORINE. 



grms. of salt, at 12*5, it lasted six to seven minutes ; with 

 1000 cc., and the same weight of salt, it lasted fourteen to 

 fifteen minutes. At 22 the duration of the reactions was found 

 to differ but little ; which proves that the preceding difference 

 does not depend on the unequal heating produced by the re- 

 action (6-5 in the first trial, 3*2 in the second). The sulphurous 

 acid should be considerably in excess ; when operating with only 

 a very slight excess, the reaction effected at 23 lasted nearly 

 twenty minutes, instead of seven. 



All these durations of the reactions can be clearly defined 

 according to the movement of the thermometer compared with 

 the rate of cooling of a similar liquid of the same weight, and 

 brought to the same heat, but in which no chemical reaction is 

 produced. 



4. For the reaction 



4[Ba(C10 3 )a dissolved + 6 S0 2 (dissolved) = BaS0 4 (precipitated) 

 + 2HC1 (dilute) + 5H 3 S0 2 (dilute)], 



the following quantities of heat were obtained : 



Initial Heat liberated for 



temperature. Weight of salt. equivalent weights. 



23 .. 2-500 Ba(C10 8 ) a + H a O ... 213-8 Cal. 



2-500 215-2 



1-544 Ba(C10 3 ) a anhydrous ... 215-2 (2 trials) 



2-500 Ba(C10 3 ) a + H a O ... 214-3 



23 

 22 

 12 

 12 



it JW/ J-MVl V^l\_/o la T AAoV' ** * ), 



2-500 Ba(C10 s ) a + H a O ... 212-3 

 At 19 we should have, on an average ... 214-3 



On the other hand, direct trials gave for the heat liberated by 

 the action of dilute sulphuric acid on barium chlorate taken 

 with the same degree of dilution as in the preceding experi- 

 ments 



i[H 2 S0 4 dilute + Ba(C10 3 ) a (dissolved)], at 19, + 4-6 ; 



whence we obtain for the union of dilute chloric acid with 

 baryta 



i[2HC10 3 (dilute) + BaO (dissolved)] + 13-8 ; 

 and for the reduction of free chloric acid 



^[2HC1O 3 (dilute) + 6S0 2 (dissolved) = 6H 2 S0 4 (dilute) 

 ~ + 2HC1 (dilute)] liberates + 214*3 - 4-6 = + 209-7. 



5, Let us note now the following data : 



J[SO a (dissolve^ + 2H 9 + Cl f (gas) = H a S0 4 (dilute) 



+ 2Iiri ^dissolved)] liberates + 36*95 l 



H + Cl = lirl Dilute) + 39-3 



tfH, + = H a O (dilute)] + 34-5 



1 Thomson. 



