derived from Indigo-blue. 303 



This body is therefore formed by the union of 1 at. of 

 indigo-blue, 6 ats. of alcohol, and 3 ats. of acetic acid, 18 

 ats. of water being eliminated, as will be seen by the follow- 

 ing equation : — 



Indigo-blue. Alcohol. Acetic acid. 



C M H 85 N0 8 +i8HO=C 16 H 5 N0 2 +6(C 4 H fl O a )+ 3 (C 4 H 4 4 ). 

 The second series of analyses made of this body gave the fol- 

 lowing results : — 



I. 0*4420 grm. gave 1*0810 grm. carbonic acid and 0*2515 

 grm. water. 



0*6550 grm. gave 0*3865 grm. chloride of platinum and 

 ammonium. 



II. 0*4610 grm. gave 1*1820 grm. carbonic acid and 0*2745 

 grm. water. 



0*5085 grm. gave 0*3325 grm. chloride of platinum and 

 ammonium. 



These numbers lead to the formula C 40 HggNO 8 , which 

 requires 



Experiment. 

 Calculation. I. II. 



C 40 240 70*38 69-86 69*92 



H 23 23 674 6-62 661 



N" 14 4*10 370 4-10 



8 64 1878 19-82 19-37 



341 100*00 IOO'OO ioo-oo 



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

 sing that 3 ats. of alcohol and 3 ats. of acetic acid have com- 

 bined with 1 at. of indigo-blue to form 1 at. of the substance, 

 since 



Indigo-blue. Alcohol. Acetic acid. 



C 40 H 23 NO 8 +i2HO = C 16 H 5 NO 2 + 3 (C 4 H 6 O 2 )+3(C 4 H 4 O 4 ). 



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

 of A, the composition may vary extremely, without any cor- 

 responding difference in external appearance and properties. 

 The difference in composition in both cases is owing to the 

 different proportion between the elements — indigo-blue, alco- 

 hol, acetic acid, and carbonic acid — of which they are com- 

 posed. The two formulae to which the analyses of B led, 

 viz. C 62 H 35 N0 8 and C 40 H^ N0 8 , 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*3600 grm. gave 0*9790 grm. carbonic acid and 0*1605 

 grm. water. 



