176 OXYGENATED COMPOUNDS OF NITROGEN. 



Experimental results. First experiment at 12 



2Ba0 2 dissolved in 4HC1 dilute +22-02 



Reaction on Ba(N0 2 ) 2 dissolved + 43-23 



R = + 65-25 

 whence may be deduced 



x = -f 22-25. 



Second experiment at 12 



In this experiment crystallised barium nitrite was directly 

 dissolved in the hydrochloric solution of barium dioxide. 



2Ba0 2 + 4HC1 dilute +21-84 



Reaction on crystallised Ba(N0 2 ) 2 H 2 ... + 38'75 



Sum +60-59 



This experiment was purposely made with crystallised nitrite 

 of baryta in order to vary the conditions. To make it com- 

 parable with the proceeding it is necessary to add to the number 

 obtained the dissolving heat of the salt at the same temperature, 

 taken with the contrary sign, viz. -{- 4*30. 



Hence we have 



E = + 64-89 



whence may be deduced 



x = 21-49 



The two experiments have therefore given 



22-25 and 2149 

 or a mean of 



21-87 or 21-9 Cal. 



This is therefore the quantity of heat liberated in the following 

 reaction : 



Ba(N0 2 ) 2 dissolved + 2 gas = Ba(N0 3 ) 2 dissolved. 



Third process. Liquid bromine. The theoretical reaction is 

 the following : 



Ba(N0 2 ) 2 dissolved + Br 4 + 2H 2 = Ba(N0 3 ) 2 dissolved + 

 4HBr dissolved. 



Pure liquid bromine is weighed in an hermetically sealed tube, 

 say, for example, 2 '254 grms. A strictly equivalent weight of 

 pure barium nitrite is also weighed. The water is placed in the 

 calorimeter, the salt is dissolved in it, and the tube introduced. 

 When equilibrium of temperature is established the bromine 

 tube is crushed, and the whole is quickly stirred. 



The reaction of bromine on barium nitrite does not, however, 

 take place so rapidly as in the case of chlorine ; it does not 

 completely dissolve until after some time, and the solution retains, 

 even after twenty minutes, a strong odour of bromine. In a 



