- Sao ee 
46 REPORT—1857, 
C? H‘4, all these hydrocarbons may be represented by the formula # (CH?), or by the 
formula x (CH?)—y H?, 2 and y being whole numbers. The substances represented 
by the first of these formule are called by Gerhardt homologous; they evidently differ 
in composition by a multiple of CH. Mr. Foster proposes to call substances isologous, 
which, like the hydrocarbons represented by the second formula (a being constant, 
and y variable), possess similar chemical functions, and differ in composition by a 
multiple of H% In the following Table, 
C H? 
C? H* C? H? 
CHS C? H# C3 H? 
C* H8 C* HS C1 H# CH? 
CH? Cun Cerne C> H4 CH? 
Cor? CorES C® HS C' H® Chr C® H? 
C7 Hi C7 HH C7 FH? C7 As C7 Hé C7 H4 C? H2 
he formule: in each vertical column represent homologous substances, those in the 
same horizontal line represent isologous substances, The relations which exist between 
the hydrocarbons, also exist between the other corresponding terms of the various 
groups, and therefore between the groups themselves taken collectively, Each group 
may therefore be characterized by the homologous and isulogous series to which it 
belongs. 
In attempting to enumerate the most important members of each group, it will save 
time to take at once a particular instance—for example, the third group of the first 
homologous series, namely the propylic or tritylic group, Here we have the three 
following alcohols ;— 
1, Propylic alcohol, C? H* O (monatomic). 
2. Propylic glycol, C* H® O* (diatomic), 
3. Glycerine, C3 H® O8 (triatomic). 
The replacement of more or less hydrogen in these alcohols by equivalent quantities 
of oxygen, gives a number of acids; those derived from the first being unibasic, those 
from the second bibasic, those from the third terbasic. The following are the acids so 
formed, together with the alcohols from which they are formed :— 
C3H80O propyl. ale., C3 H6 O2 propion. ac., C3 H4 O08 pyruvic ac., C3 H? O4 (unknown),.. unibasie. 
C3 H8 O2 propyl. glyc., C} HS 03 (unknown), C3 H4 04 nicotic ac. ?, C3 H2 O05 me, oxalic ac., bibasic. 
C3 H8 03 glycerine, C3 H6 04 (unknown), C3 H4 05 (unknown), C3 H2 06 (unknown). . terbasic. 
The alcohols may be regarded as the leading members of each group. Around each 
of them and their derived acids, various chlorides, anhydrides, nitrides, and other 
bodies of which these are typical, are to be placed. 
Nomenclature.—In the nomenclature here proposed, the root of the name of any 
substance denotes the group to which it belongs, the termination, its place in the group, 
or its chemical function. The root is, in most cases, formed by the combination of two 
Greek numerals; the first denoting the homologous, the second the isologous series to 
which the substance belongs*. Thus, allylic alcohol, C? H®O, belongs to the second 
homologous and to the third isologous series, counting from above downwards, and 
from left to right in the Table of hydrocarbons given above; it therefore belongs to 
the deutritie group. Similarly, angelic acid, C? H® 0?, belongs to the deupentie group, 
that is, to the second group of the fifth isologous series, or to the fifth group of the 
second homologous series. 
The following are the terminations suggested to denote some of the best defined 
chemical functions :— 
-yl denotes a monatomic radical: Example—Tetrexyl =C* H®=phenyl. 
-ene denotes a diatomic radical: Example—Penteptene=C’ H®=radical of chlo- 
robenzol (Wicke, Ann. Ch, Pharm. cii. 358). 
-ise denotes a triatomic radical: Example—Tritise=C* H'=glyceryl. 
-ylia denotes nitride of -yl: Example—Tetrexylia (or tetrexia)t=C° H? N=nitride 
of tetrexyl. 
* Only so much of each numeral is used as is necessary to characterize it distinctly, and for 
convenience of pronunciation. In the case of bodies of the first homologous series, the names 
express only the isologous series to which they belong. Thus, the names of the methyl, ethyl, 
propyl, ... compounds are formed from the roots prot-, deut-, trit-, «.. instead of from proprot-, 
prodeut-, protrit-, ... 
+ The syllable y? may be omitted when it is followed by an additional termination, 
