CHLORIMETRY. 



251 



that the liquid may occupy 2000 divisions of the 

 graduated burette. 100 measures, therefore, of this 

 solution contain 0.7 grm. of arsenious acid, and the 

 solution of chlorine which is required to convert this 

 into arsenic acid, contains 0.5 grm. of chlorine, since 1 

 equiv.= 99 of arsenious acid, requires, for its conver- 

 sion into arsenic acid, 2 equivs.= 71 of chlorine. 



Five grras. of chloride of lime are weighed off, inti- 

 mately mixed with water, by trituration, rinsed into a 

 cylindrical (Fig. 36) glass, and so much water added 

 that the whole may occupy 200 measures of the 

 burette. 



Figs. 36. 



37. 



39. 



One hundred measures of the arsenic-solution are 

 then, by aid of the pipette (Fig. 37), introduced into a 

 beaker, diluted with water, an excess of hydrochloric 

 acid added, and the liquid coloured with one or two 

 drops of sulph-indigotic acid. 



The solution of chloride of lime is well mixed by 

 agitation, introduced into the burette (Fig. 39), and 

 added to the colored arsenic-solution until the color 

 just disappears. The solution of chloride of lime 

 required to produce this effect contains 0.5 grm. of 

 chlorine. 



For example, if 90 measures of the solution of chlo- 

 ride of lime had been employed, the 5 grms. of chloride 



