Dr. E. J. Mills on Elective Attraction. 519 



85 per cent, of plumbic nitrate usually escapes the reaction un- 

 injured, prevents moreover the useful employment of that com- 

 pound. Argentic nitrate was therefore selected. 



30 grms. of argentic nitrate and 23 cubic centims. oxychloride 

 were placed in a bulb, which communicated by means of an 

 elongated neck with three U-tubes. The first of these was of 

 small size and immersed in cold water ; the second was larger, 

 and covered with ice and salt; the last and remotest was plunged 

 in a mixture of ice and hydrous calcic chloride, the temperature 

 of which was —35°. The interior of this apparatus had been 

 carefully dried. The bulb was placed in a water-bath, the heat 

 of which was raised gradually. On observing the phenomena 

 presented during the reaction, it was found that they sensibly 

 agreed with what have already been recorded in this paper. A 

 very little oxychloride escaped from the bulb-apparatus, and was 

 retained by the first two U-tubes. In the third U-tube about 

 1*5 cubic centim. of a tawny distillate had collected ; its vapour- 

 density, as determined by Dumas's process, was found to be 

 1*981 at 99°'6. Assuming it to be a mixture of nitric peroxide 

 and nitrylic chloride, the composition and volume of the vapour 

 at that temperature were as follows : — 



cub. centims. 

 Nitric peroxide . . 99'6 

 Nitrylic chloride . . 35'5 = 0*0414 grm. chlorine. 



I35I. 



This result was confirmed by determining the chlorine in the 

 vapour-density flask ; its amount was found to be 0"0436 grm. 

 The powerful frigorific means employed did not suffice to re- 

 tain all the gaseous products of the reaction. A pungent and 

 pale yellow vapour escaped continually from the apparatus ; 

 but although it reddened and bleached moist litmus, it was 

 quite unlike chlorine in odour. This, body was arrested by 

 aqueous aniline hydrochloride ; but another and colourless gas 

 still escaped absorption. 



The strict determination of the presence or absence of free 

 chlorine under the conditions here indicated did not appear to 

 be a surmountable problem. I contented myself, therefore, 

 with the above results, which point conclusively to the evolu- 

 tion of (at least) nitric peroxide, nitrylic chloride, and most 

 probably oxygen. 



Discussion. 



(1) By selecting and employing the same unit of measure- 

 ment throughout namely the common chemical unit (P^O^) 

 of phosphoric pentoxide, it appears that the nitrates are con- 



