198 M. Cahours on Organo-metallic Compounds. 



less, mobile, etherial liquid: it is distanethyle, discovered by 

 Frankland and Buckton. It is not a radical, for it does not 

 unite directly either with oxygen, chlorine, or iodine. Cahours 

 describes a number of the salts of the oxide of stanethyle, which 

 is obtained by decomposing iodide of stanethyle by ammonia. 

 They are mostly obtained by directly combining the base and 

 acid. The salts are decomposed by the action of heat. 



The iodide of sesquistanethyle y Sn 2 (C 4 H 5 ) 8 1, is a heavy oil 

 which boils between 235° and 238°. When treated by iodine, it 

 gives iodide of ethyle and iodide of stanethyle. 



Oxide of sesquistanethyle is obtained in the state of hydrate, 

 (C 4 H 6 ) 3 Sn 2 O, HO, by treating the iodide with an aqueous solu- 

 tion of potash and distilling : it crystallizes in colourless prisms, 

 which melt between 44° and 45°. 



Its aqueous solution acts upon colouring matters like a strong 

 base. Its salts are soluble, crystallizable, and possess a strong 

 odour ; they are obtained by treating the oxide with strong acids. 



The iodide of methyle, when treated either with pure tin, or an 

 alloy of sodium and tin, yields similar results to those of iodide 

 of ethyle. Cahours has, however, not been able to isolate stan- 

 methyle and distanmethyle in a state of purity. 



The salts of stanmethyle and of sesquistanmethyle are ob- 

 tained by directly combining the oxides with acids. They cry- 

 stallize extremely well. The salts of sesquistanmethyle are 

 isomorphous with those of sesquistanethyle. 



Cahours concludes from these researches that tin forms three 

 definite compounds with methyle, which may be written in the 

 following manner : — 



SnMe, Sn 2 Me 3 , SnMe 2 , 

 SnAe, Sn 2 Ae 3 , SnAe 2 , 



which correspond to the oxides of tin, 



SnO, Sn 2 3 , SnO 2 . 



If the vapour-densities are taken into account, the formula of 

 some of them must be doubled, and they may then be compared 

 to the formula of bichloride of tin. Thus : 



Sn 2 Ae 4 = 4 vols. vap. Distanethyle. 



Sn 2 Ae 8 CI = 4 vols. vap. Chloride of sesquistanethyle. 



Sn 2 Ae 2 CI 2 = 4 vols. vap. Chloride of stanethyle. 



Sn 2 CI 4 = 4 vols. vap. Bichloride of tin. 



The relations between all these compounds are seen in the 

 action of iodine on distanethyle. Iodide of ethyle is separated, 

 and according to the proportions of iodine taken, equivalents of 

 ethyle are successively removed and replaced by iodine, until 

 biniodide of tin is ultimately obtained. 



