94 THE SUGAR INDUSTRY. 
thus make affining practicable. Sugar of a small grain which can 
not be affined must be melted without preliminary treatment. 
2. Melting.—The affined or unaffined sugar is melted in warm 
water, either pure or after having been used to ‘‘sweeten” off the 
char filters. The melting tanks are usually on the ground floor of 
the refinery. They are heated by steam coils and contain stirring 
apparatus or mixers and false bottoms to retain coarse impurities such 
as straw, stones, bits of leaves, and so on. The color of the solution 
from the melters varies from a light straw color to a dark brown, 
according to the character of the sugar melted. It is pumped from 
the melting pans into the defecators. 
3. Defecating or clarifying.—The purpose of defecating or clarifying 
is to remove the gums, organic acids, dirt, and other impurities from 
the solution. The defecators are heated by means of steam coils, 
the temperature being kept at 160° F. or above. Formerly blood 
was used to clear the solution of impurities. Upon heating, the 
blood would take up the impurities and rise to the surface, where it 
was removed by means of a skimmer and filtered to recover the sugar 
it contained. It is more common now to clarify with lime, perhaps 
with the addition of soda, caustic soda, alum, clay, or powdered 
bone char. 
The clarified juice is classified as “firsts,” ‘“‘seconds,” and so on 
according to the sugar or sirup from which it is obtained. The sugar 
obtained from the original melting is called “firsts.” ‘“‘Seconds” 
are obtained from the sirup used in affining or centrifugaling “firsts.” 
“Seconds” are often run back and mixed with the unclarified juice 
producing ‘‘firsts.”” The molasses or wash from the ‘‘seconds” will 
produce “thirds.” The “wash” sirups are of different purity and 
may be classified accordingly. The first aflining sirup or wash is 
very dark and impure, while the last one is almost pure, as can be 
judged from the methods employed. The designations vary slightly 
in different refineries. 
4. Filtration is necessary to remove the coarse foreign matter 
that is held in suspension in the sirup, as well as the precipitates 
formed by the lime and other clarifying agents. For this purpose 
bag filters are used. 
5. Decolorization by means of bone-black filters is perhaps the 
most important part of the routine work in sugar refining. The 
value of bone char consists in that it decolorizes the sirup by absorbing 
the coloring matter and organic salts. The action of the char is 
purely physical and not chemical. It absorbs through its pores not 
only the coloring matter, but also lime, most of the organic and inor- 
ganic salts (except nitric acid and chloride salts), and sugar. How- 
ever, the sugar and some of the inorganic and organic salts not easily 
absorbed, such as acetic acid salts, are easily washed out. : 
Bone char has long been considered indispensable in sugar refining. 
It is one of the greatest items of cost, as the material is expensive 
  
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