168 THE MODERN THEORY OF CHEMICAL TYPES. 



phenomena .agree not, the rcigon is souglit, and the correct type determined by 

 experiment. 



But others emph)y this method as a means of comparing chemical reactions, 

 and as suggestive of new experiments. Such write f'ormulic sometimes according 

 to the ohl nomenchiture, and sometimes t.akc great liberties with the types, 

 viewing the same body in different types ; for example, taking aldehyde 



(C4 114 ex.) .iccording to the type „, thus: '•* jj-^ ' > or, according to the 



, 11 ) ,, ,1 C4 H:, I n 

 typejr > O2, thus: * ,t' > O2. 



A very serious defect, in my opinion, in the type method is that it pl.aces the 

 hydrogen acids and salts in a different type from the oxygen acids and salts ; 

 while tlie analogies existing between these acids and salts furnish urgent reason 

 why they shouhl have the same constitution, Avhich similarity chemists have 

 always labored to discover. It is not fair to constitute a type ammonia founded 

 on the chemical analogies of it and the compound ammonias, and at the same 

 time place hydro-chloric and nitric acids in different types. And yet, by the 

 present method, they cannot come in the same type, because, first, oxygen can- 

 not come in the hydrogen type, jy > ; jj ? ; and second, in the Wciter-type 



TT I ^^ ^^'^ oxygen outside of the bracket is differently combined, compared 

 with the oxygen of an oxy-radical replacing H. Thus nitrate of potassa must 

 be y^ ■" i O2, and not i/- "^ [ j (since O4 and O2 are differently combined,) and 



CI ) 



chloride of potassium can only be jt- > . 



In concluding the subject, it may be observed that by the former method of 

 writing formula?, the binary nature of chemical compounds, owing to the polarity 

 of their atoms, was kept prominent ; while this is not the case with respect to 

 type formula;, although in these the polarity of the atoms is not denied, but 

 kept in subordiu.ate view. 



Whatever be the faults or merits of the type method, it has, by placing bodies 

 before us in a new relation, suggested experiments (which, perhaps, Avould not 

 have been otherwise suggested) which have led to important discoveries. At the 

 present time, not to understand this method of writing formulae is to be excluded 

 from following the course of modern chemical progress. 



