126 Cellulose 



to approximately 20 p.ct., was analysed, the total Fe being 

 determined as Fe 2 O 3 , the CN as NH 3 . 



Fe 2 O 3 = 6-i p.ct. = 4-27 Fe; N = 3'i5 p.ct. = 5*85 CN. 

 Whence the ratio 



or 



Fe:CN = i :3. 



A portion of the fibre was further treated until the increase 

 of weight amounted to 40 p.ct., and then analysed with the 

 following result : 



Fe 2 O 3 = 14-0 p.ct. = 9-8 Fe N = 9-3 p.ct. CN. 

 Fe:CN = g: = 0-175: 0-357 = 1: 2. 



By the continued interaction of the fibre- substance and the 

 ferric ferricyanide the Fe'" appears to be deoxidised, and in 

 exhausting the fibre-substance with dilute alkali in the cold, 

 ferrocyanide is dissolved, as of course is to be expected. 



It is obvious that we are dealing with an aggregate and 

 the product of a mixed reaction ; the ratios Fe 2 (CN) 6 and 

 Fe 3 (CN) 6 determined as above for the product in successive 

 stages are therefore not to be taken as more than approximate 

 indications of the composition of the colouring matter deposited 

 in the fibre. 



The mechanism of the reaction and the question of the 

 composition of the resulting blue cyanide are further elucidated 

 by the following experiments : 



Equivalent solutions were prepared as above, and in two 

 experiments with equal weights of fibre the solutions were 

 mixed in the proportions : 



A. 3 of ferric chloride to 2 of ferricyanide ; 



B. 2 3 .. 



