990 TJ2 A XS ACTIONS OF THE AjfEUICAX INSTITUTE. 



and conditions still wrapt in ohscnrity. Equivalence involves liiii'licr 

 questions than tliose of quantity and quality, as tliese terms are a])j)lied 

 to ponderable matter, for two elements having diverse cliemical func- 

 tions and widely dittbrino- atomic weights, like hydrogen and chlorine, 

 sometimes assume the same relative position in the mazes of chemical 

 combination. In many instances, attractive force or affinity seems 

 subservient to fitness of place; hence has arisen the distinction of 

 chemical and mechanical or molecular types, which can only imply 

 that one kind of force is more etlective than another in completing 

 "what may be termed the symmetry of the chemical structure. The 

 smallest quantity of an element which can enter into combination has 

 an invariable weight, and doubtless a normal sphere of attraction, 

 which may be modified in its relations to that of another element, on 

 changing the rate and range of the undulations of the interatomic 

 medium throiigh tlie ngcnev of light or heat ; or on disturbing its gene- 

 ral equilibrium by wliat is termed electric force. It is evident that the 

 minute changes which a molecule undergoes in chemical action 

 involves a problem of motions too complex for com[>lete solution. 



Considerable diversity of opinion still exists among advanced chem- 

 ists, l)oth as to the best form of t}qies and the highest saturating 

 power of sev'cral clelnents. Indeed, the value of the same element 

 varies so m.nch nnder different conditions, that some writers, regarded 

 ;ts ;ii' ;:i>;!'*(-^. .iTo no\v incHncd to iucludc .all Simple bodies in two 

 (• cing combining units expressed by even numbere, 



and ilio otii-:jr Tnose (expressed bv odd 'nnmbei's. Some of the 

 late f ■■'■ • • ■ '■ •' - '^ :«■ advocates of the new viev\\s would 



'^;V dividiug line of distinction. Pro- 

 his admirable lectures on 

 i^. i'c[)ortctl ;;y tiiO London Chemical iV^Ar^as 

 ■ to us dintomic in the binoxyd of nitrogen." 

 die new notation,' is a combination of one 

 ntom of nitrogen (14j with one of oxygen (IG). 'The statement taken 

 literally would place nitrogen in botlv classes alluded to. With equal 

 C'jn'^istency it may be asserttpd that niti'ogen in the pcroxyd of nitro- 

 gen is tetratomlc ; and by a parity of reasoning nitrogen becomes a 

 Proteus among' types! Kow, while it is admitted that only two- 

 thirds of the nornnil saturating power of an atom of nitrt)gen is 

 ex]iended in combining with one of oxygen, it may with great plausi- 

 bility be assnraed that the remaining unexpended combining nnit 

 actually determines the value of this body as a monad radical. It 



