APPENDIX I. 467 



deduced from ethane, ethylene, and acetylene, by methylation, by methylena* 

 tion, by acetylenation and by carbonation. 



1. C 3 H 8 o CHjCHaCH^ out of CH 8 CH 3 by methylation. This hydro- 

 carbon is named propane. 



2. C 3 H fl CH 3 CHCH, out of CH 3 CH 3 by methylenation. This eub 

 stance is propylene. 



8. C 9 H e - CHjCH^CHj out of CH a CH 3 by methylenation. This sub. 

 stance is trimethylene. 



4. C 3 H 4 CH 3 CCH out of- CH 3 CH 3 by acetylenation or from CHCH by 

 methylation. This hydrocarbon is named allylene. 



6. C 3 H 4 out of CH 3 CH 3 by acetylenation, or from CHjCHa by 



methylenation, because C ^ H C ^? H This body is as yet unknown. 



6. C 8 H 4 = CHjCCHj out of CHjCH, by methylenation. This hydro* 

 carbon is named allene, or iso-allylene. 



fTTPTT 



7. C 8 Hj e ^ Q a out of CH 3 CH 3 by symmetrical carbonation, or out 



of CH^CHj by acetylenation. This compound is unknown. 

 i~i 1-1 



8. CgH^ = ^ out of CH 3 CH 3 by carbonation, or out of CHCH by 



methylenation. This compound is unknown. 



If we bear in mind that for each hydrocarbon serving as a type in the 

 above tables there are a number of corresponding" derivatives, and that every 

 compound obtained may, by further methylation, methylenation, acetylena* 

 tion, and carbonation, produce new hydrocarbons, and these may be followed 

 by a numerous suite of derivatives and an immense number of isomerio 

 substances, it is possible to understand the limitless number of carbon com* 

 pounds, although they all have the one substance, methane, for their origin* 

 The number of substances is so enormous that it is no longer a question of 

 enlarging the possibilities of discovery, but rather of finding some means of 

 testing them analogous to the well-known two which for a long time have 

 served as gauges for all carbon compounds. 



I refer to the law of even numbers and to that of limits, the first enunciated 

 by Gerhardt some forty years ago, with respect to hydrocarbons, namely, 

 that their molecules always contain an even number of atoms of hydrogen. 

 But by the method which I have used of deriving all the hydrocarbons from 

 methane, CH 4 , this law may be deduced as a direct consequence of the 

 principle of substitutions. Accordingly, in methylation, CH 3 takes the place 

 of H, and therefore CH 4 is added. In methylenation the number of atoms of 

 hydrogen remains unchanged, and at each acetylenation it is reduced by two, 

 and in carbonation by four, atoms that is to say, an even number of atoms/ 

 of hydrogen is always added or removed. And because the fundamental 

 hydrocarbon, methane, CH 4 , contains an even number of atoms of hydrogen, 

 all its derivative hydrocarbons will also contain even numbers of hydrogen, 

 and this constitutes the law of even numbers. 



The principle of substitutions explains with equal simplicity the conception 

 of the limiting compositions of hydrocarbons CH.,,, +2 , which I derived, in 



