1902.] 



and Statics under the Action of Light. 



09 



vapour, which are most difficult to detect with ordinary chemical or 

 physical means, are quite enough to diminish or accelerate the velocity 

 of combination of CI2 and CO, quite extraordinary precautions in the 

 preparation of perfectly pure CO and Cl 2 had to be taken. 



The carbon monoxide was prepared in the manner given by Lord 

 Rayleigh, i.e., from sodium formate (35 gr.), two parts sulphuric acid 

 (200 gr.), and one part of water (100 gr.). The other precautions 

 taken were : — All the vessels were first heated and evacuated by means 

 of a Topler pump to about 0*01 mm. ; all the liquids used were first 

 boiled in a vacuum so as to expel the air, carbonic acid, &c, from the 

 same. To free the generated CO from the last traces of sulphurous 

 acid and carbonic acid the gas was passed through a solution of caustic 

 potash free from air, then through a U-tube containing solid caustic 

 potash, and a long tube containing phosphorus pentoxide. The first 

 portion of the prepared CO was removed, all the vessels having been 

 again heated and evacuated, and the vessels then filled with CO ; 

 before each experiment on light the CO was first removed from all the 

 vessels and new CO prepared. Only quite freshly prepared CO could 

 be used for the experiments. 



The chlorine was prepared by heating of perfectly pure and dry 

 cupric chloride (CUCI2) free from hydrochloric acid, which, if it is once 

 formed, is almost impossible to remove from the same. The CuCl 2 was 

 prepared from precipitated copper and dry chlorine. The copper was 

 first reduced in a tube with drawn-out ends in a current of hydrogen, 

 the hydrogen removed by evacuation. A dry current of Cl 2 , washed 

 and well dried, was passed over the copper first in the cold, then while 

 the copper was heated to about 250°, and then the tube sealed up at 

 the two drawn-out ends. The tube was afterwards connected with 

 another tube containing phosphorus pentoxide. 



The vessels, in which CO and Cl 2 were prepared, were connected 

 with the quartz vessel or the glass bulb in which the gases were 

 exposed to light by means of capillary tubes, and the quartz vessel or 

 glass bulb was connected with a manometer, the mercury of which was 

 protected from the action of Cl 2 by a column of concentrated sulphuric 

 acid free from air on the top in the capillary. The quartz vessel con- 

 sisted of a short glass cylinder with glass rims, on which two quartz 

 windows were fixed, and it contained a thermocouple to indicate the 

 temperature of the gas during the reaction. Before the gases were 

 introduced into the quartz vessel, the quartz vessel, manometer, &c, 

 were evacuated and heated and washed with CO, the Cl 2 and CO com- 

 pletely removed (the chlorine by means of a removable pump), all the 

 vessels again heated and evacuated to about 0*01 mm., the Cl 2 and CO 

 again freshly prepared in the dark (on account of the properties of the 

 deduction periods), introduced into the quartz vessel under special con- 

 ditions, and here sealed up with a hand blow-pipe. 



