80 DR. EDWARD SCHUNCK ON SOME 



In this case the composition is to be explained by sup- 

 posing that 3 ats. of alcohol and 3 ats. of acetic acid have 

 combined with i at. of indigo-blue to form i at. of the 

 substance, since 



Indigo-blue. Alcohol. Acetic acid. 



C4oH,3N08+i2HO=CieH5NO,+3(C,H,0,)+3(C,H,0,). 



It appears, therefore, that in the case of this body, as in 

 that of A, the composition may vary extremely, without 

 any corresponding difference in external appearance and 

 properties. The difference in composition in both cases is 

 owing to the different proportion between the elements — 

 indigo-blue, alcohol, acetic acid, and carbonic acid — of 

 which they are composed. The two formulae to which 

 the analyses of B led, viz. Cjj H^j NOg and C^o H^^ NOg, 

 differ from one another by a multiple of CH, and they 

 therefore represent homologous bodies. 



C. 



This body is formed in relatively small quantities, and I 

 only obtained sufficient for one analysis, which yielded the 

 following results : — 



0'36oo grm. gave 0*9790 grm. carbonic acid and o*i6o5 

 grm. water. 



0*5435 grm. gave 0*5175 grm. chloride of platinum and 

 ammonium. 



Hence it is to be inferred that the formula is C^gH,, NO^, 

 which requires 



Cal( 



C,s 168 



Hu " 



N 14 



O4 3^ 



225 



This formula leads to the conclusion that the formation 

 of the compound is due to the union of i at. of indigo-blue 



ilation. 



Experiment. 



74-66 



74-16 



488 



4-95 



6-22 



5-98 



14-24 



14-91 



I00"00 



lOO'OO 



