of Chemical Operations, 425 



It is absolutely impossible to express this last compound in 

 our existing notation. 



Similarly, tetratomic alcohol, which would have for its for- 

 mula C(OH) 4 , an alcohol which is unknown, but of which the 

 derivatives are known, ought to be written, according to Sir 

 B. C. Brodie, a 2 *;]* 4 . But Sir B. C. Brodie's theory shows 

 equally an alcohol « 2 /ef D , which our existing notation rejects as 

 impossible. 



Finally, besides the triethylamine, (a 2 /c 2 ) 3 )a 2 v, and the iodide 

 of tetrethyl-ammonium (<x 2 /c 2 ) 4 (a 2 v) (aw), the notation of Sir 



B. C. Brodie shows the compound ammonias (a 2 /e 2 ) w aV and 

 the compound iodides of ammonium, (aV 2 ) w+1 (aV) («&>). 

 These last bodies, unlike the preceding, might be written in 

 our existing notation, which would permit the expression of 

 these compounds by the formulae 



(C 2 H 4 )»NH 3 and (C 2 H 4 )»+'NA 4 C1; 



but our notation allows us also to consider them as compounds 

 of substitution, instead of considering them as compounds of 

 addition, which limits their number. 



Now, up to the present time there has never been obtained 

 a number of chlorine, bromine, or iodine derivatives of a 

 hydrocarbon greater than the number of the atoms of hydro- 

 gen which this hydrocarbon contains. There has never been 

 obtained a number of alcohols greater than that of the chlo- 

 rine, bromine, or iodine derivatives. Finally, there has never 

 been obtained for each monatomic alcohol a number of com- 

 pound ammonias greater than three, and a number of com- 

 pound salts of ammonium greater than four. 



On the other hand, the law of even numbers, which Sir B. 



C. Brodie has so much at heart, is far from being demon- 

 strated, since the exception of the oxides of nitrogen cannot be 

 eliminated unless we admit the dissociation of our element 

 nitrogen. But even if the law of even numbers were abso- 

 lutely demonstrated, it would still not prove that a body which 

 cannot exist in a free state may not exist in a state of combi- 

 nation. And, finally, if this explanation itself be inadmissible, 

 since the notation a of Sir B. C. Brodie shows an innumer- 

 able multitude of improbable bodies, and he does not point 

 out to us any rule for eliminating them, which is contrary to 

 that which actually occurs in the existing notation (and to 

 that which occurs in the notation of Sir B. C. Brodie), for the 

 bodies which do not satisfy the law of even numbers, the 

 hypothesis a appears to us in all points inferior in the existing 

 state of science to the hypothesis a 2 . 



Now the hypothesis a 2 is nothing else than our existing 



