PRODUCTS DERIVED PROM INDIGO-BLUE. 81 



with I at. of alcohol and 2 ats. of acetic acid, and the 

 elimination of 8 ats. of water, for 



Indigo-blue. Alcohol. Acetic acid. 



D. 



This body is formed in abundance during this process, 

 and I think it probable that its composition is always the 

 same, as the following analytical results will tend to show: — 



I. 0*3540 grm. of the substance, dried at 100° C, and 

 burnt as usual, gave 0'936o grm. carbonic acid and 0"i635 

 grm. water. 



0'5630 grm. gave 0*5540 grm. chloride of platinum and 

 ammonium. 



II. 0*2325 grm., prepared on another occasion, gave 

 0*6030 grm. carbonic acid and 0*0985 grm. water. 



0*5700 grm. gave 0*5435 grm. chloride of platinum and 

 ammonium. 



The formula with which these numbers most closely 

 correspond is C56Hi4.NjO,o, which requires the folloAving 

 values : — 



Calculation. 



C56 336 7^79 



H24 24 5'i2 



Nj 28 . 5-98 



Oio 80 17-11 





II. 



72" 1 1 



7073 



5"i3 



470 



6-i8 



5-98 



16-58 



18-59 



100-00 



loo-oo 



468 ICO'OO 



The deficiency of carbon in the second analysis may be 

 partly due to the extreme difficulty with which the com.- 

 bustion of the substance is effected — a difficulty which is 

 always experienced in the case of such bodies as become 

 charred when heated without previously melting. 



If the formula of C, Cj,g H,, NO^., be doubled, it will be 

 found to differ from that of D merely by 2 HO less. The 

 formation of both bodies is therefore to be explained in the 



SER. III. VOL. III. G 



