Dr. E.J. Mills on Elective Attraction. 509 



(2) 0'7086 grm. sodic chloride with 4*5103 grms. phosphoric 

 oxychloride, heated as before to 120°*5, gave an increase of 

 •0007 grin. = 00-09 per cent. 



(3) 08274 grm. potassic chloride and 3-5664) grms. oxychlo- 

 ride, heated for 1 hour to 127°*5, increased by '0016 grm.= 

 00*19 per cent. 



(4) 19680 grm. phosphoric pentoxide was gradually heated 

 in the air-current to 148° during one hour, and increased '0002 

 grra. = *01 per cent. ; and this, after mixture with a considerable 

 quantity of two combined preparations of oxychloride and slow 

 heating for j hour to 145"^ in the air-current, increased by 0114 

 grm. = 00 59 per cent. 



(5) 1*3018 grm. baric nitrate, heated with an unweighed 

 excess of oxychloride to 123° during 1^ hour, acquired '0006 

 gi'm. = 00*05 per cent. The residue contained an infinitesimal 

 trace of chlorine. 



I now proceed to the description of individual reactions. 



Argentic Nitrate. 



The ordinary commercial salt not unfrequently contains 

 copper and some sulphate derived from the incompletely puri- 

 fied hydric nitrate employed in its preparation. The salt actually 

 used m these experiments was made by precipitating argentic 

 chloride from the commercial nitrate, washing repeatedly with 

 hot aqueous sodic acetate, and reducing the chloride by fusion 

 w^ith a mixture of sodic carbonate and chloride. The silver so 

 obtained was dissolved in specially prepared commercial hydric 

 nitrate containing but little sulphate; and the solution, after 

 evaporation to dryness, was fused and crystallized from alcohol. 

 In this way all the ferric nitrate was decomposed and removed 

 simultaneously with the argentic sulphate. Desiccation and 

 crystallization from water completed the purifying process. 



This nitrate, as was the case with each of its successors, was 

 first reduced to a powder of moderate fineness; it was then dried 

 at 180° and allowed to remain for some time to cool over oil of 

 vitriol. When brought into contact with the oxychloride, there 

 was a slight increase of temperature; and chemical action was 

 indicated by the now dead-white appearance of the nitrate, the 

 orange coloration of the oxychloride, and the evolution of minute 

 bubbles of gas. At about 40° the action was evidently a maxi- 

 mum, and a tawny gas of rapidly deepening colour came ofi^ 

 freely, smelling of aqua regia, and capable of reddening and 

 afterwards bleaching litmus. At this time also numerous light 

 flakes were observed floatmg in the oxychloride. At about 71° 

 the reaction had apparently terminated ; no more coloured gas 

 was expelled, and the liquid resumed its ordinary appearance. 



