200 Mr. W. Odling on the Formulation of 



H3C.CH3 = C 2 H 6 H3O.H3C.OH3 or H 2 C"\ riTT = C 3 H 8 



(CH 3 fCH 2 .CH 3 (S5 2 ' CH3 



HC^CH 3 =C 4 H 10 HC^CH 3 = C,H 12 C^*« ^ H 

 (CH 3 1CH 3 |gg 



H3C.H 2 C.H 2 C.H 2 C.H 2 C.H 2 C.CH 3 = C 7 H 16 . 



"With the increase in the number of marsh-gas residues 

 coalescing to furnish a paraffin, the modes of their conceivable 

 arrangement, subject to the above-mentioned condition, become 

 almost infinitely various. In all paraffins at present known, 

 however, the modes of arrangement are reducible to four (Schor- 

 lemmer) ; and the paraffins are accordingly divisible into four 

 subclasses, namely: — a dimethyl subclass, typified by the hydro- 



f PIT 

 carbon H 2 C -J ^ jj 3 or H 2 C(CH 3 ) 2 ; a trimethyl subclass, typified 



fCH, 



by the hydrocarbon HC< CH 3 or HC(CH 3 ) 3 ; a tetramethyl 



(CH 3 



(CH 3 



I PIT 

 subclass, typified by the hydrocarbon C <J p^x 3 or C(CH 3 ) 4 ; and 



(.CH3 

 another tetramethyl subclass, typified by the hydrocarbon 



H 3 cj HC - CH tCH3 0r H6(CH 3 ) 2 ' 



the perpendicular hyphen or line used in this last formula ser- 

 ving to indicate the coalescence of the two formyl residues 

 written one under the other. 



Variously constituted penta-, hexa-, and yet more highly 

 methylated paraffins are readily conceivable, but have not actu- 

 ally been met with. Moreover the known members of the 

 two tetramethylated subclasses are but few and comparatively 

 unimportant. 



The dimethylated and trimethylated paraffins have been dis- 

 tinguished for some time past as normal and isoparaffins respec- 

 tively ; and it being useful to have distinctive names for the 

 other two subclasses, the subclass typified by the hydrocarbon 

 C(CH 3 ) 4 may be conveniently designated as that of neo- or 

 latest paraffins, and the subclass typified by the hydrocarbon 



1 as that of mesoparaffins, — the prefix meso- sug- 



HC(CH 3 ) 2 / \ * . 



gesting by its sound a special connexion between this and the 



