93 



Iodide of mer- 

 curous methyl. 



On the other hand, the action of concentrated sulphuric or hydro- 

 chloric acid furnishes hydride of methyl or marsh gas, with deposition 

 of crystals of the corresponding chloride or sulphate. 



+ HC1= C 2 H 3 Hg 2 Cl -f C 2 H 3 ,H. 



The salts of mercurous methyl, and the radical mercuric methyl, 

 are both decomposed by the action of a dilute acid and clean zinc, 

 into metallic mercury and gases. 



Mercuric methyl furnishes with bichloride of tin a crystalline 

 compound, which decomposes, on addition of water, into chloride of 

 mercurous methyl and a soluble tin salt. The same chloride also is 

 produced by the action of terchloride of phosphorus. 



Mercuric methyl is a ready solvent of caoutchouc, resins, and 

 phosphorus. It, however, has but little solvent action on sulphur. 



Some interest attaches to the circumstance that iodide of mer- 

 curous methyl is easily produced by heating mercuric iodide with 



mercuric methyl. 



Mercuric ethyl. 



The author has also prepared the radical of mercuric ethyl. From 

 its proneness, however, to decomposition at the high temperature at 

 which the reaction is effected, he has not been able to obtain more 

 than sufficient to make a qualitative examination of the new body. 

 It boils at a temperature above that of waterj and burns with a more 

 lurid flame than is exhibited by mercuric methyl. 



III. " On Certain Formulae for Differentiation." By ARTHUR 

 CAYLEY, Esq., F.R.S. Received November 26, 1857. 



(Abstract.) 



In seeking for a formula in the theory of multiple definite inte- 

 grals, I was several years ago led to investigate the successive differ- 

 ential coefficients of (>/#+x_ Vx + p)*, and the results which I 

 then obtained are given in my paper, " On certain formulae for dif- 

 ferentiations, with applications to the evaluation of definite inte- 



