By Mr. J. Smytu, Jun., C.E., F.CS. 47 
the blue colour of dilute solution of indigo. The latter test is the 
most convenient for bleachers who generally use indigo for testing 
their bleaching vats for chlorine, and as the washing is easily 
effected, is sufficiently accurate. 
The filtered liquid to which the washings are first added is then 
made up with water to 500 C.C. 
It is easy to know when this liquid contains an excess of 
alkali, by the addition of a small portion of the lime bleaching 
liquid (sol. of bleaching powder,) which if such be the case gives 
a white precipitate (carbonate of lime). 
For each examination 50 cub. cent. of this liquid aretaken, and the 
per-centage of chlorine determined either by Gay-Lussac or Penot’s 
method with arsenious acid, or by Otto’s method with protoxide 
of iron or indeed by any of usual methods. In the methods with 
arsenious acid, I find it a great improvement to dissolve the 
arsenious acid in glycerine instead of potassa or soda. If there is 
not time to filter tolerably accurate results can be obtained by 
making up the unfiltered liquid to 500 cub. cent., indeed more 
accurate I consider than by the mere milky solution of the 
bleaching powder. 
Made up of this strength and filtered the alkaline bleaching 
liquid is clear and colourless of a sp. gr. of 1:007. I have made 
it however of a sp. gr. of 1:233 containing one of chlorine to nine 
of the liquid, which in this case is slightly green. It has a 
pleasant oily feeling to the touch, contrasting favourably with 
the rough unpleasant feeling of the lime bleaching liquor. 
Its bleaching effect is very much altered by a slight departure 
on either side from its neutral point (viz. when the addition of 
either an alkaline or lime solution will cause no precipitate). 
In the manufacture of this liquid for bleachers, the commercial 
carbonated soda ash is used with bleaching powder. 
