313 



various constitution, which it might be impossible afterwards to 

 separate, except by working on a large scale, which, considering the 

 costliness of the materials, had its disadvantages. Perhaps success 

 might attend the use of one of Dr. Frankland's mirrors for concen- 

 trating the sun's rays. 



For obtaining the lead-radical, recourse was had to well-dried 

 chloride of lead, which was introduced into a flask containing zinc- 

 ethyl. The chloride immediately turned black, from the deposit of 

 metallic lead, whilst moderate heat was disengaged. An excess of 

 chloride was used, and the mass incorporated by stirring with a 

 glass rod. After applying a gentle heat for a few minutes, the 

 floating clear liquid was pipetted off. This substance is apparently 

 a compound of zinc-ethyl and the lead radicals. It fumes slightly 

 in the air, and no digestion with chloride of lead appeared to resolve 

 it entirely into the lead base. 



A great part of the zinc-ethyl, however, is removed by subsequent 

 distillation ; but the temperature should not be permitted to rise 

 above 140 or 150 C. The substance in the retort is then treated 

 with water and dilute hydrochloric acid, when the radical separates, 

 and sinks in the form of colourless drops. When distilled cautiously, 

 the thermometer soon rises to 200 ; but beyond this point the vapour 

 is very prone to decomposition, with deposit of metallic lead. 



From this tendency to change, there is some difficulty in obtaining 

 the substance wholly pure from bodies with lower boiling-points. 

 The larger portion came over between 198 to 202. Its specific 

 gravity was found to be 1*55. 



Analysis led to the formula 



PbC 8 H 10 ,orPb(C 4 H 5 ) 2 . 



It should, however, be noticed that a trifling excess in the per- 

 centage of carbon obtained, showed an increase rather than a decrease 

 in the number of equivalents of ethyl. 



This radical, for which the provisional name of plumbic bis-ethyl 

 is suggested, is a colourless fluid, possessing little or no odour. It 

 is insoluble in water, but perfectly miscible with ether. It burns 

 readily with a beautiful orange-coloured flame, edged with blue, and 

 gives off fumes of oxide of lead. 



The radical appears to be incapable of forming salts without a 



