ANALYTIC PROCESSES 25 
houses. As corrosive vapors are given off, it 
must be placed under a hood; but a special 
form of apparatus is now made which does not 
require an escape-pipe. 
When the liquid has become colorless or very 
light straw yellow, it is allowed to cool, diluted 
with 100 c.c. of water if the smaller form of 
Fic. 1. 
flask has been used, the liquid transferred to 
the distilling flask, and the digestion flask rinsed 
with two portions of water, 50 c.c. each, which 
are also transferred to the distilling flask. With 
the larger form of flask the dilution is made at 
once by the cautious addition of 200 c.c. of 
water. Granulated zinc, pumice stone, or 0.5 
