BARIUM DIOXIDE PROCESS. 175 



We may pass from one to the other by following two different 

 cycles. 



FIRST CYCLE. 



Ba(N0 2 ) 2 dilute + 2 = Ba(N0 3 ) 2 dilute ...... x 



2Ba0 2 anhydrous + 4HC1 dilute = 2BaCl 2 dilute + 2H 2 + 55'58 



Sum ...... + 55-58 + x 



SECOND CYCLE. 

 2(BaO + 0) = 2Ba0 2 anhydrous ............ + 12-1 



2Ba0 2 + 4HC1 dilute, then reaction of this solution on dis- 



solved Ba(N0 2 ) 2 .................. R 



Sum ...... ... R -f 12-1 



K being determined by experiment it is easy to calculate x. 

 The experiment is carried out as follows : 



A known weight, p, of anhydrous barium dioxide, say 8 '5 grms. 

 for example, is dissolved in the calorimeter by dilute hydro- 

 chloric acid; the quantity of heat liberated, Q, is measured. 



With 8'50 grms. it is practically equal to -^- Cal. To the 



zo 



liquid is then added a quantity of barium nitrite strictly 

 equivalent to the barium dioxide employed, or 6'20 grms. 

 The nitrite should be dissolved beforehand in twenty-five times 

 its weight of water, and the temperature of the solution 

 accurately measured a moment before it is mixed in the calori- 

 meter with the hydrochloric acid and solution of barium dioxide. 

 Immediately upon this mixture being effected, several pheno- 

 mena are produced and succeed each other rapidly, the solution 

 becomes yellow, then for a moment it becomes turbid, as if a 

 precipitate were forming ; a few excessively fine gaseous bubbles 

 appear for an instant without giving rise to the production 

 of an appreciable volume of gas; then the liquor becomes 

 perfectly clear. A minute, and even less, suffices for the 

 accomplishment of all these effects. 



At this point the liberation of heat is at an end, and the nitrite 

 entirely changed into nitrate. 



From the data observed is calculated the heat liberated during 

 the last metamorphosis, say Q'. 



Hence we have, calling E the equivalent of barium dioxide, 

 Ba0 2 = 84' 5 grms. as the expression for the heat liberated. 



therefore the heat liberated in the transformation of nitrite of 

 baryta into nitrate will be 



x = B + 121 - 55-58 = B - 43'5. 



