IGG THE MODERN THEORY OF CHEMICAL TYPES. 



The table illustrates the method of writing the formulse of bodies according 

 to the types of water, hydrogen, and ammonia, to which they respectively belong. 

 Determination.s of the specitic gravities of the vapor of water and of hydrogen 

 show that the furmuhc II O and II (0 = S and II = 1) agree to a condensation of 

 ttvo volumes. In order, therefore, to make types of these bodies, their formulae 

 must be doubled so as to correspond to a condensation of four volumes, which 

 is the atomic volume of the greater ^lart of organic compounds. 



The formula for ammonia N II3 already corresponds to four volumes, e. g., 

 2 vols. N + 6 vols. 11 = 8 vols, condensed to 4 vols. N H3. 



It will be observed that, in the table, compounds of a basic character are 

 placed to the left hand, those of acid nature to the right hand, while salt or 

 neutral bodies occupy positions in the middle of the table. 



It will be observed, further, that in the formulae of the bodies according to the 



types TT > O2 and |, > the electro-negative elements are placed in the bracket 



to the left hand, and these are distinguished into a superior atom of hydrogen, 

 capable of being replaced by chlorine, &c., or an acid radical, and an inferior 

 atom of hydrogen susceptible of being exchanged for a metal or basic radical, 

 while the electro-negative elements, oxygen, sulphur, &c., occupy positions to 

 the right hand, outside of the bracket. 



The relations existing between anhydrous or hydrated acids or bases ; the 

 difference between hydrogen acids and oxygen acids ; the nature of acid, base, or 

 salt, are more readily perceived by a close examination of the table than by the 

 most extended description. It will be seen by this inspection how the ammonia 



salts are represented. xr TT ^ [ ^2 is the acetate of ammonia. By adding H 



TT 1 

 to the type ammonia we have a new type tt }• N, ammonium, which enables 



the formation of salts, according to the ammonium theory, by introducing this new 

 type into the type of water. Thus diethyle-methyle-amyle-ammonium would be 



H -) O4H3O2 ^ 



C4 II5 ~) 

 N. Its hydrated oxide C4 H5 i -j^ 

 C2 II3 I 

 CioHji 3 J CioHii 



C4 H5 



XT I 



•N. 



> O2. Its acetate C4 II5 ( at r O2. 



O2 H3 (^'- I 

 The homologous series may thus be generalized by this system of nomencla- 



ture — c. g., ordinary alcohol is p tt ? O2 ; p tt > O2 is any alcohol, and 



P TT O i "* n (n+ ; J 



1'^ ^ 1 ^^^ corresponding acid of the same homologous series. 



Another principle, which has been adopted in tbe type method, consists in 

 the assumption of radicals capable of replacing Hg or H3 in the types. Such 

 radicals are diatomic when they replace H2, and are represented thus, (",) and 

 triatomic ( '") when they replace H3 ; and the types of water, hydrogen, and 

 ammonia are doubled or trebled to form new types by which bibasic or tribasic 

 acids or salts may be represented. Thus : 



niBASIC ACIDS. 



Type. Sulphuric acid. Succinic acid. Tartaric acid. 



TRIBASIC ACIDS. 

 Type. Phosphoric. Meconic. Citric 



JMOr ^^'"'\0r CuUO,'")^ C,2H5 0«'")^ 



