TRANSACTIONS OF THE SECTIONS. 25 



or equivalent in functions to two atoms of hydrogen ; a third group, like nitrogen, 

 phosphorus, and arsenic, is triatomic, or equivalent for the most part to three 

 atoms of hydrogen ; while a fourth group, like carbon and silicon, is tetratomic, or 

 equivalent in functions to four atoms of hydrogen, and so on. 



It would lead us too much into detail were I to attempt to show how this idea 

 of the atomicity of the elements has heen applied, and is still in process of applica- 

 tion, to the study of the formation of compounds in general, how it endeavours 

 to explain the existence of a limit to their numher, and how it even teaches us to 

 anticipate their possible varieties. 



Among the subjects connected with its development is its bearing upon isome- 

 rism, or the remarkable fact of the existence in many cases of two or more bodies of 

 different properties but yet composed of the same elements combined in identically 

 the same proportions. Upon this subject, which, at our last Meeting, was charac- 

 terized by Dr. Odling as the chemical problem of the day, a suggestive theoretical 

 paper was published, about twelve months ago, by Dr. Oram Brown ; whilst, in the 

 same direction, Cahours, Kekule, Beilstein, Fittig, and several other chemists have 

 published valuable experimental researches. Inquiries of this kind are now 

 acquiring special importance from the numerous cases of the formation of such 

 isomeric bodies by the methods of synthesis and substitution, which are daily 

 multiplying. 



Closely connected with the same subject are the investigations into the consti- 

 tution of the more complex organic acids, which have been prosecuted so actively 

 during the last live or six years, and which, in the hands of Kolbe, Frankland, 

 Perkin and Duppa, Kekule, Wurtz, and their pupils, have made such rapid 

 progress. 



During the past year Frankland and Duppa have especially signalized themselves 

 by their researches upon the lactic and the acrylic series. Two years ago, Frank- 

 land, commencing with oxalic ether, and acting upon it with zinc ethyl, obtained 

 from it leucic ether by substituting ethyl for a portion of the oxygen contained in 

 the oxalic ether; and afterwards, conjointly with his friend Duppa, he has genera- 

 lized this reaction. Still more recently, these chemists have traced the connexion 

 between the lactic and the acrylic or oleic series, by reactions in which the abstraction 

 of the elements of an atom of water from the basylous portion of a member of the 

 lactic group converts it into the corresponding member of the acrylic series. These 

 relations will be readily understood by representing the different compounds by 

 symbols, as follows : — 



Oxalic acid. Leucic acid. 



(1) II, G 2 e., + (G., H 5 ) 2 -e = H, HG 2 (G 2 H 5 ) 2 3 . 



Leucic or 

 dicthoxalic acid. Ethylcrotonic acid. 



(2) H 2 G 2 (G 2 H,) 2 9 3 -H 2 9 =H, G 2 (G 2 H 6 ) (G 2 H 4 )» 2 . 



In these and kindred investigations, the necessity for the introduction of fixed 

 principles of nomenclature for regulating the construction of names for the recently 

 discovered compounds has been sensibly felt ; and indeed the changes in notation 

 rendered necessary by the alteration in the values assigned to the atomic weights 

 of many of the chemical elements have rendered a general revision of the system 

 of chemical nomenclature a matter of pressing importance. Probably few subjects 

 coidd more usefully occupy a portion of the time of this Section during the ensuing 

 week than a thoughtful consideration of the changes which it may be expedient to 

 introduce. The meeting of chemists from various parts of Furope with many from 

 distant parts of our own country affords an excellent opportunity for discussing a 

 subject of this kind, where any conclusions, to be practically effective, must secure 

 the concurrence of a majority of the active cultivators of the science. 



Did time permit, it would be easy to mention other investigations in the organic 

 department of chemistry, scarcely less interesting than those already alluded to, 

 such as those on the synthesis of the aromatic acids by Kekule, who has pre- 

 pared both benzoic and toluic acid by the graduated action of sodium on an 



