384? Professor Bunsen on the Radical 



acid, the chlorideof cacodylis sucked Fig. 2. 



into the bulb a, also containing the 

 zinc. The open end of the vessel is 

 then immediately closed with the 

 blowpipe. It is exposed to the tem- 

 perature of 100° C. for three hours, 

 in a water-bath. The zinc is readily 

 dissolved without any evolution of 

 gas, and the solution becomes of a 

 dark colour. On cooling to 50° C. 

 larfre cubic crystals are formed, 

 which are redissolved by heating. 

 These crystals are probably a com- 

 bination of chlorideof zinc and chlo- 

 ride of cacodyl. When the zinc 

 is no lono-er acted upon at 103° C, the contents of the bulbs 

 appear converted into a dry mass of salts, which, upon an in- 

 crease of temperature to 1 10° or 120° C, melts into an oily- 

 like liquid. After the whole apparatus is warmed, the point 

 of the receiver b is opened under cold water previously 

 boiled. Upon the entrance of the water, upon the cooling 

 of the apparatus, it is again sealed, and the water is con- 

 ducted into the distillation bulbs. After a short digestion, 

 a solution of chloride of zinc is formed, the zinc in excess 

 remaining with a clear surface, and leaving the radical at 

 the bottom as an oily liquid. This liquid is then trans- 

 ferred into the drying apparatus, and when perfectly dry is 

 sucked up again into the ilistilling a})paratus, and digested for 

 a short time with clear zinc, by which means a small quan- 

 tity of chloride of zinc is formed. It is then distilled, and 

 comes over as clear as water. At a temperature of — 6° C. 

 laro-e prismatic shining crystals are formed. After two-thirds 

 of the solution has crystallized, the remaining solution is again 

 distilled, and this is repeated three times over. The solution 

 is finally put into a tube filled with carbonic acid. 



The analysis of this liquid was conducted in the usual 

 manner with oxide of copper. The arsenic sublimed in fine 

 crystals in the back part of the tube without the formation of 

 any arsenical copper or any arsenical salts. The quantity of 

 arsenic was ascertained by weighing the tube before and after 

 heatinf'. The analysis gave the following results: — 

 " 1 2. 



Substance 0-620 gr. 0-500 gr. 



Carbonic acid .... 0-500 0-402 



Water 0-306 0-200 



Tube before heating. 62-681 60-670 



... after heating . 61-869 60-020 



