32 BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE 
cooled to atmospheric temperature instead of to standard tempera- 
ture, and since the hydrometer readings at the atmospheric and 
standard temperatures do not usually differ greatly, the term “ ordi- 
nary temperature’”’ or ‘‘atmospheric temperature’”’ is used in this 
bulletin to refer to readings corrected to the standard temperature 
oF 175° ©2635 2): 
CLARIFICATION BY LIME ALONE 
By C. F. Watton, Jr., Bureau of Chemistry, U. S. Department of Agriculture 
In addition to chemical clarification employing both sulphur 
dioxide and lime, use is sometimes made of lime and phosphoric acid 
as the clarifying agents, and at times lime alone is used. The lime- 
phosphoric acid method is not as popular with sirup manufacturers as 
the lime-sulphur process, but the application of lime as the sole 
clarifying agent is common enough to merit consideration with the 
other methods of clarification. 
Manufacturers sometimes desire to make sirup of the so-called 
Georgia type in large-capacity plants. The simple boiling and skim- 
ming method, employing direct-fire, rapid, open evaporation in a 
shallow layer, ali the way from juice to sirup, has been found to give 
the best-quality sirup of the so-called Georgia type (p. 69). The 
largest plants, however, are not as a rule ideally equipped to use this 
prevess, and consequently do not usually produce sirup of equally 
good quality. A decision to engage in the large-scale manufacture 
of such sirup, therefore, depends upon market conditions, or, more 
specificaily, upon the demand for a somewhat lower grade sirup 
resembling the Georgia type. : 
As the larger factories ordinarily have no equipment for boiling 
and skimming the juice and evaporating rapidly in a shallow layer, 
they must use comparatively large and deep tanks, in which the juice 
is heated to boiling and the coagulated impurities are permitted to 
separate out. When no chemicals are used, however, the impurities 
settle to the bottom or come to the top so slowly that much valuable 
operating time is lost. As it is desirable to run the grinding part of 
the plant to capacity, the juice must be handled at a sufficiently 
rapid rate to “keep out of the way of the mill.” Juice treated with 
lime settles more quickly and is more completely clarified than that 
which is simply heated to the boiling point. The lime-clarified juice 
may then be evaporated in open brush pans of the Louisiana type or in 
vacuum evaporators (p. 53). 
When the juice is excessively acid the use of lime is an additional 
advantage, in that it partially neutralizes the acidity and gives the 
sirup a somewhat milder flavor. One disadvantage is that the sirup — 
is usually darker than that made by the typical small-scale process, ~ 
owing partly to the use of lime and partly to the large-scale method 
of evaporation. Another objection is that the flavor of the sirup is 
somewhat different from that of typical Georgia-type sirup. : 
In operating the lime process on a large scale, it is best to use the _ 
minimum quantity of lime which will enable the factory to use the 
settling tanks or clarifiers efficiently enough to ‘‘keep out of the way © 
of themill.” The less lime that can be used the better the quality of the © 
sirup willbe. If the cane is of good quality and there is ample meee. 7 
capacity, it is sometimes possible to keep the juice at its original © 
