196 
BROMINE IN MINERAL WATERS. 
waters. Although the process of M. Heine cannot lay 
claim to the most perfect accuracy, we have no doubt it 
will be found preferable to any other method now in use.] 
The usual qualitative test for bromine, consists in mixing 
the solution supposed to contain the bromides with some 
aether, then carefully adding chlorine water and leaving the 
fluid in quiet ; the aether collects on the surface. It is co- 
lourless when no bromine is present, faintly yellow when 
there is little, slightly or strongly brown when in greater 
quantity. To make use of this test in quantitative investi- 
gations, several precautions must be taken. In the first 
place, it had to be ascertained whether the mother-leys, 
which are sometimes of a yellow colour, would impart this 
colour to the aether ; experiments proved this not to be the 
case. On adding chlorine water to the leys, they were 
more or less decolourized, a proof that the yellow colour 
was owing to organic substances. It is further known that 
aether assumes a faint yellow tint when it is shaken with 
chlorine water ; it became requisite to know whether a 
small quantity of chlorine water is capable of producing 
this colouration, or only large quantities. A considerable 
amount of chlorine water was employed, before its influ- 
ence on the colour of the aether became perceptible. In 
order to conclude with probability as to the quantity of 
bromine, so much chlorine water had to be employed that 
all the bromine was set free and taken up by the aether. It 
was therefore requisite to determine this quantity, by the 
addition of more or less chlorine water to liquids containing 
the same amount of bromine, and by comparing the tints of 
the aether*. The volatility of the aether and the bromine 
had also to be considered, and the glasses had to be made 
so that they could be closed tight and very quickly, and at 
the same time be almost entirely filled. And lastly, it was 
requisite to use equal quantities of aether, &c, for all the 
*It is necessary to use the strongest possible chlorine water recently pre- 
pared. 
