689 



expressed, step by step, by the following equations, tbe tin-salt being 

 supposed to be added to the zincethyl : 



I. 2ZnC 4 H 5 + SnCl 2 =Sn (C 4 H 5 ) 2 +2ZnCl 

 II. 3Zn C 4 H 5 + 2Sn C1 2 = Sn 2 (C 4 H 5 ) 3 C1+ 3Zn Cl 



III. ZnC 4 H 5 + SnCl 2 =Sn C 4 H 5 C1+ ZnCl; also 



IV. 2Zn C 4 H 5 + Sn Cl = Sn C 4 H 5 + Zn C 4 H 5 + Zn Cl. 



Double compound ? 



I have failed in satisfactorily separating the radical stannic ethyl 

 from the excess of zincethyl, as represented in the last reaction. By 

 the addition of water great heat is generated, and tin is thrown down 

 in its metallic state. 



By distillation also, the radical stannic ethyl is similarly broken up, 

 2Sn C 4 H 5 = Sn (C 4 H 5 ) 2 + Sn. 



Plumbic diethyl. 



In the abstract above alluded to, I have stated the difficulties 

 which at that time prevented my obtaining the lead radical in a state 

 of purity. This difficulty arises from its tendency to decompose 

 suddenly at a point below that of ebullition. This disadvantage is 

 entirely obviated by conducting the distillation in vacuo, or at least 

 under reduced atmospheric pressure. The organo- metal was found 

 to distil unchanged under a pressure of 7*5 inches of mercury at a 

 temperature of 152 C., the barometer at 30*5 inches. This is a 

 remarkable lowering of the boiling-point, which at ordinary atmo- 

 spheric pressures appears to be a few degrees above 200 C. 



Analysis gave numbers leading to the formula 

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



Plumbic diethyl is a limpid and colourless fluid, possessing a 

 specific gravity of 1*62. It burns with an orange flame, tinged at 

 the edges with pale green, and disengages whilst burning much oxide 

 of lead. 



The only salts hitherto prepared from this radical seemed formed 

 on the type of the sesquioxides. By passing excess of hydrochloric- 

 acid gas over the organo-metal, hydride of ethyl is liberated, and 

 chloride of diplumbic triethyl is obtained. 



2Pb (C 4 H 5 ) 2 + H Cl=Pb 2 (C 4 H 5 ) 3 C1+C 4 H 5 H. 

 The chloride is a fine crystalline body, occurring in long needles, 



