Law of Density-Numbers. 195 



In ammonia, NH 3 , x=9 ; and thus we find that in the 

 three series of bodies of which the three following are types 

 there is a steady increase of x apparently without limits: — 



Ammonia, NH 3 , #=9, 



Ethylene diamine, N 2 C 2 H8, 



#=14, 



Triethylene triamine, N 3 C 4 H 13 , #=19; 



the difference NC 2 H 5 therefore corresponds to #=5, or in the 

 atomic weight =43, in density numbers =10, numbers com- 

 parable with those observed in the case of the elements (see 

 above). 



It is also possible to use the property of the constancy of x 

 in substitution-products to determine the value of some 

 density-numbers, especially that of chlorine. It is found 

 that, in general, x does not change when 1, 2, 3, or more 

 atoms of chlorine are substituted for 1, 2, 3, or more atoms 

 of hydrogen in a body of the formula C^H^O,.. Table XIX. 



Table XIX. 

 Toluol and its Chlorine substitution-products. 



Formula. 



a. 



go 

 observed. 



T. B/a. 



C 7 H 8 



C T H 7 01 



92 



126-5 

 161 

 195-5 

 230 



15 



18 

 21 

 24 



27 



108 N 

 164 L 

 206 W 

 237 L 

 255 L 



621 



62-18 



62-48 



62-61 



61-98 





CLH-OL 



7 o^ 3 



CJELCL 





N=Noad ; L=Limpricht ; W=Wicke. 



shows this clearly in the case of the four chlorine deri- 

 vatives of toluol, C 7 H 8 ; for when the density-number of 

 chlorine is taken as 4, the value of the constant Tn/a is all 

 through 62*2, and x is equal to 5. In the case of benzol, 

 C 6 H 6 , ^=4, and so also for C 6 H 5 C1, C 6 H 4 C1 2 , and C 6 H 3 C1 3 ; 

 while #=4-5 for C 6 H 2 C1 4 and C 6 HC1 5 . But =5 for C 6 C1«. 



I have published, elsewhere*, extended tables showing 

 clearly this constancy of x in chlorine substitution-products. 



* Annalen, Wiedemann, 1879, p. 134; J. A. Groshans, Bin neues 

 Gesetz, Leipzig, Barth, 1882, p. 43; J. A. Groshans, De la nature des 

 Elements, Haarlem, he*ritiers Loos]es, 1875, p. 47. 



2 



