112 
MANUFACTURE OF BORAX. 
95° to 105°, octahedral crystals are obtained, which contain 
only 5 atoms of water of crystallization, and consequently 
entail a very considerable loss in product. This is not to be 
feared in the above process, but great attention should be 
paid to the specific gravity of the ley; for if the hot ley, 
placed aside to crystallize, has been reduced by boiling to 
beyond 1-180, octahedral crystals are likewise obtained. It 
should moreover be observed, that the boracic acid, which 
has been introduced according to the above directions for 
the first time, is by no means sufficient to convert the whole 
of the soda into biborate, but an excess of soda has a very 
beneficial influence on the crystallization. It is moreover 
advantageous not to remove the dissolved lime from the 
caustic ley, but rather to add a little free caustic lime, as 
this serves partially to destroy the sulphates contained in 
the crude boracic acid. After three days the first crystalli- 
zation is complete. The crystals are collected and broken, 
washed with the above mentioned dilute caustic ley, and 
placed aside ; the borax ley, on the contrary is mixed with 
the wash liquors and placed aside, in order that it may de- 
posit the sulphate of lime formed and any other impurities. 
As soon as the ley has become clear, it is carefully drawn 
off, boiled down, and during this operation 8 lbs. more bora- 
cic acid gradually added to it, and it is then treated as above. 
The ley which is now left still requires from 2 to 5 lbs. bo- 
racic acid ; what remains after this third crystallization may 
be saturated with sulphuric acid, and obtained as sulphate 
of soda. 
The re-crystallization of all the crystals obtained must 
generally be repeated twice, for which purpose they are 
dissolved in %\ parts rain water, the ley brought by boiling 
to the above-mentioned specific gravity, and conveyed boil- 
ing hot into a wooden vessel protected from rapid cooling. 
The evaporation of the residuous ley is repeated. The 
crystallization is always terminated within two or three 
days. There is no need of filtration except on the last re- 
crystallization. The product amounts, when good sub- 
