514 



Dr. E. J. Mills on Elective Attraction. 



average time of each operation was about an hour and three 

 quarters. 



When water was added to the residue, the evolution of heat was 

 very decided (being much greater than in the case of the three 

 preceding nitrates), and the residue dissolved entirely. 





I. 



XL 



III. 



Nitrate taken 



1-0718 



1-4113 



117° 



22-82 

 33-47 

 42-77 



1-2278 



1-6309 



116° 



23-45 

 33-62 

 41-19 



1-2014 

 1-5694 

 120°-5 



23-38 

 32-08 

 42-56 



Residue obtained 



Temperature 



Composition of the residue, viz. : — 



Phosplioric oxide 



Sodic nitrate 





99-06 



98-26 



98-02 



Value of « 



1-65 



6 1-69 



1-77 





The mean of the three quotients is a =1*70. 



Potassic Nitrate. 



The starting-point in the preparation of this nitrate was hy- 

 dropotassic tartrate. The tartrate, after two crystallizations, was 

 dried, ignited, and extracted with dilute aqueous hydric chloride 

 (during which process some hydric sulphide was disengaged). 

 On evaporation of the solution and addition of more hydric chlo- 

 ride, potassic cbloride was deposited ; and this salt, after wash- 

 ing with concentrated aqueous hydric chloride, was dried, and 

 subsequently evaporated with hydric nitrate that had been dis- 

 tilled below the boiling-point. When the preparation was 

 attempted by directly treating the ignited tartrate with hydric 

 nitrate, the product contained sulphate. The sample referred to 

 below contained an infinitesimal trace of chloride, but was other- 

 wise pure ; on evaporation with aqueous hydric chloride it yielded 

 73*70 per cent, potassic chloride, 73*75 per cent, being the 

 number required by theory. The nitrate was dried for several 

 hours at a minimum temperature of 160°. 



Phosphoric oxy chloride gave rise to immediate action. At 

 40°~54° the mass in the reactioii-tube became flesh-coloured and 

 viscid, apparently giving off chlorine and nitric peroxide as the 

 temperature increased. At about 93° the liquid state was re- 

 stored^ and perfect decoloration took place at 102°. These phe- 

 nomena are remarkably similar to those observed with the sodium 

 salt. The mean duration of an experiment was nearly an hour 

 and a half. 



Special precaution had to be taken in bringing the residue 



