190 



Both series of radicals are chained together by these reactions, aud 

 we may view acetyl and propionyl as formyl, the hydrogen of which 

 is replaced hy methyl and ethyl. 



Formyl =C 2 (H) O 2 



Acetyl =C 2 (C s H 3 ) O 2 



Propionyl =C 2 (C 4 H:,) O 2 . 



There is no doubt that the same relation exists between the hydro- 

 carbons of the other series of radicals and the radicals of the corre- 

 sponding acids, between allyl, C 6 H 3 , and the radical of acrylic acid, 

 acryl C 6 H 5 O 2 , and between methylene, C 2 H 2 , ethylene, C 4 H.,, pro- 

 pylene, &c., and the radicals of the bibasic acids, which are homo- 

 logues of succinic acid, C 8 H 6 O 8 . 



The biatomic radicals are in general far less studied than the 

 monatomic radicals ; still they occur in many compounds, and are 

 met with in different departments of chemistry. 



In addition to the terms already mentioned, we find them in the 

 phenyl, benzyl, naphthyl and other series. 



In the hope of adding some facts to the history of the polyatomic 

 radicals, I have made some experiments with chloride of ethylene, 

 C.H.Cl,. 



This compound, as well as the bromide of ethylene, refused to act 

 in many instances ; in others it underwent the same change which is 

 induced by the action on it of a solution of potassa in alcohol, split- 

 ting into the compound C 4 H 3 Cl and hydrochloric acid. 



On boiling chloride or bromide of ethylene with an alcoholic so- 

 lution of sulphocyanide of potassium, a very definite reaction takes 

 place. The change being completed, the alcohol is separated by 

 distillation, and the residue treated with a small quantity of cold 

 water in order to remove chloride or bromide of potassium, which is 

 produced, and the excess of sulphocyanide of potassium. The more 

 or less coloured residue is then dissolved in boiling alcohol, and the 

 solution, after digestion for some time with animal charcoal and a 

 few drops of hydrochloric acid, filtered whilst hot. This solution 

 deposits on cooling fine white, very brilliant and large rhombic plates 

 of a hard and brittle substance*. 



* Whilst M. Buff was engaged with these researches, M. Sonnenschein has 

 communicated some experiments made in the same direction, which have likewise 



