ACETYLENE SERIES. 131 



4, Collidine (Aldehydine), ^ C 8 H n K Is obtained 

 by heating an alcoholic solution of acetic aldehyde- 

 ammonia to 120-130, or of ethylidene chloride (p. 46) 

 with alcoholic or aqueous ammonia to 160. Colorless, 

 liquid, but slightly soluble in water ; specific gravity, 

 0.944 ; boiling point, 176. 



In addition to these the following bases have been 

 separated from coal-tar, but not carefullv investigated : 

 Parvoline C 9 H 13 ISr, boiling point, 188 ; corindine C 10 H 15 ^", 

 boiling point, 211 ; rubidine C u H 17 ]Sr, boiling point, 

 230, and viridine C 12 H 19 ^, boiling point, 251. 



THIKD GROUP. 



A. HYDROCARBONS, C n TL 2n ~ 2 (ACETYLENE SERIES). 



The hydrocarbons of this series differ from those of 

 the ethylene series, in that they contain two hydrogen 

 atoms less ; and are produced from these when their 

 bromides are heated in sealed tubes with alcoholic 

 potassa. They contain either two carbon atoms united 

 by triple union (acetylene CHiCH) or twice two car- 

 bon atoms united by double union (diallyl CH 2 :CH. 

 CH 2 CH 2 .CH:CH 2 ). 



1. Acetlene. 



Formation and preparation. Is formed directly from 

 its elements under the influence of an electric flame, 

 which is produced in a current of pure hydrogen be- 

 tween points of purified carbon ; is also formed by the 

 decomposition of carbon-calcium with water; by the 

 action of heat on ethylene and marsh gas (hence con- 

 tained in coal-gas) ; by the decomposition of the latter 

 by electrical sparks ; by imperfect combustion of a great 

 many organic bodies ; by heating ethylene bromide or 

 monobromethylene with alcoholic potassa ; and in many 

 other ways. 



