METHOD OF DETERMINING IRON IN WATERS. 351 



mgr. 



Weight of ammonio- ferrous sulphate taken =58*00 



= 8*28 of iron. 

 After oxidation made up to 1 litre ; 



.*. 1 cub. cent. =0*00828 milligr. Fe. 



c. c. mgr. 



(a) (1) 50 of this solution taken, = 0*414^ 



4* 1 of iron solution required, =0*410 >Fe. 

 (2) 4-2 „ „ „ =0-420 J 



As a mean of these two experiments, it is found that 



mgr. 



the solution contained 8*30 Fe. 

 Calculated . . . . 8*28 „ 



Difference = +0*02 



(b) 500 cub. cent. ( = 4-142 milligr. Fe) of the original 

 solution taken, and diluted to one litre. 



,*. 1 cub. cent.= 0*0041 4 milligr. Fe. 



c. c. mgr. 



(1) 100 of this solution taken, =0-414^ 



4*2 required, =0*420 



(2) 50 of this solution taken, =0*207 



2*i required, = o*2io v 



>Fe. 



mgr. 



As a mean, the solution contained 4*20 Fe. 

 Calculated . . . . 4*14 „ 



Difference = + 0*06 



(c) 225 cub. cent. (=1-863 milligr. Fe) of the original 

 solution taken and diluted to 1 litre. 



.*. 1 cub. cent. =0*00 1 863 milligr. Fe. 



c. c. mgr. 



100 of this solution taken, =0'i86?l „ 

 i*8 required,' = o*i8ooj 



.*. the solution contained i*8oo Fe. 

 Calculated .... 1863 „ 



Difference = - 0063 



