1866. ] with the supply of water to Calcutta. 225 
product is distilled over and emptied into a tube graduated into 100 
divisions of 10 fluid grains each, the bottles washed out with distilled 
water and added to the tube to make up 100 measures of liquid which 
isto be thoroughly mixed together. Two wide mouthed bottles or jars 
of as nearly the same size as possible are provided, into each of which 
25 fluid grains of the Hydrarg-Jodide solution is introduced with 
some distilled water. Then ae one of these an aliquot part of the 
distilled liquid is poured, say {5 or 4, so as to produce a distinct colour, 
and the bottle is filled up Al water. Another similarly graduated 
tube or burette has been’ prepared ready filled with the standard 
solution of muriate of ammonia, and this is carefully added to the 
second bottle, until the colour produced is as exactly as possible of the 
same shadeas that of the first, both bottles being of course made equally 
full. The quantity added is then noted, and then calculated on the 
whole. Thus: suppose 74 fluid grains of the standard solution of 
muriate of ammonia has-been required, this is equal to 74 & .000L 
grains or .0074 grains ammonia. If 25 measures of the distilled liquor 
has been used for trial, this is }th of it, consequently the whole contains 
0074 & 4 = .0296 grains ammonia, and as this was from 10,000 
fluid grains of water, by consequence the standard quantity of 100,000 
fluid grains water contains .296 grains ammonia. 
The process requires great care, that there be no accidental 
admixture of ammonia. The vessels must be scrupulously clean, the 
distilled water and the lime used must be carefully examined to make 
sure that they contain no ammonia. The plan of measuring the 
distillate enables the operator to repeat the trial in case of accident 
or uncertainty. It is better to work with rather weak colours, as the 
eye can better detect differences of shade: .0074 grains ammonia is 
too much for a 2000 grain bottle: any size of bottle may be used, 
provided the two bottles be as exactly as possible alike in size, shape 
and capacity. 
