358 THE TSOCHLOES OF NOVA SCOTIA. VICKERY. 



potassium chromate as an indicator, and determining the 

 end point by comparing the color of the solution under 

 examination with one clouded by a previous precipitation 

 of approximately the same amount of silver chloride as would 

 be obtained in the titration. This artifice was used through- 

 out the experimental work. It was found that a definite 

 amount of silver nitrate solution was necessary in order 

 that pure distilled water, colored with potassium chromate 

 should give the distinct color which served as an end point. 

 This amount was determined by numerous experiments 

 to be 0.09 cubic centimeters, and this amount was subtracted 

 from the amount of silver nitrate solution necessary to give 

 the end point reaction during the standardization experiments. 

 In the standardization made a year later, this number was 

 found to be .04 cc. By this means the ratio between the 

 silver nitrate solution and potassium chloride solution was 

 obtained, and the necessary dilution of the silver nitrate 

 calculated. Thus the volume of the solution containing 

 the excess amount of silver nitrate could be determined 

 and removed, and the solution again made up. 



Standardization Data. 



The average of four accurate determinations of the 



ratio between the chlorine and silver solution gave:— 



Chlorine : Silver : : .9565 : 1 



Hence, the amount silver contained : proper amount : : 



1 : .9565 



107.93 

 1 mg. chlorine is equivalent to =3.045 mg. silver 



X : .003045 : : 1 : .9565 



.-.X = .003183 



which is the actual amount of silver in 1 cc. solution. But,, 



lOOOcc. should contain 3.045 mg. silver; 



1000X3.045 ^_^ . . ^ . ^. 



•*• o =9o/.0 cc. solution contain the pro- 



0.183 



