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234 REPORT OF THE COMMISSIONER OF AGRICULTURE, 6 5 
delay is liable to entail loss of sugar by inversion. After the water is” 8 
put into the cells of the battery with the chips, the temperature is — 
carefully kept above that at which fermentation takes place most © 
readily, and the danger of inversion is thereby reduced, But withall 
‘the precautions known to science up to this point the utmost celerity 
is necessary to. secure the best results, There is here, however, a 
natural division in the process of sugar-making, which will be further 
considered under the heading of ‘‘ auxiliary factories.” Any partof . 
the process heretofore described may be learned in a few days by. 
workmen of intelligence and observation who will give careful at- 
tention to their respective duties. 
BOILING THE SIRUP TO GRAIN THE SUGAR. 
This operation is the next in course, and is performed in what is 
known at the sugar factory as the strike-pan, a large air-tight vessel 
from which the air and vapor are almost exhausted by means of a 
suitable pump and condensing apparatus. As is the case with the 
saccharine juices of other plants, the sugar from sorghum crystal+ 
lizes most readily at medium temperature. There are two ways of 
proceeding, ‘The simplest is to boil the sirup in the vacuum pan 
until it has reached about the density at which crystallization be- 
gins, then draw it off into suitable vessels and set it away in a hot 
room (about 110° to 120° ¥.) to crystallize slowly. The proper dens- , 
ityis usually judged by the boiler, by observing the length to which 
a sample of the hot liquid from the pan can be drawn. This is 
called the ‘‘string-proot” test. A far better method is to “‘ boil to 
grain” inthe pan. This is better because it gives the operator con- 
trol of the size of the grain within certain limits, because it gives a 
better a laericed sugar, and more important still, because with 
proper aie lit gives a better yield. Several descriptions of this deli- 
cate operation have been published, After reading some of the best 
of these, the writer found, on attempting to boil to grain, that more 
definite instruction was necessary ; and after obtaining the instruc- 
tion it became apparent that while almost any one can learn to 
‘boil to grain,” yet to obtain the best yield requires personal skill 
and powers of observation and comparison which will be obtained 
in widely different degrees by different persons. 'To become a good 
sugar-boiler one must be an enthusiastic specialist. The Depart- 
ment of Agriculture was fortunate in securing for this important 
work the services of Mr. Frederick Hinze, a native of Hanover, 
Germany, and a graduate of the ‘‘Sugar Industry School” at 
Braunschweig. 
The process of boiling to grain may be described as follows: A - 
portion of the sirup is taken into the pan and boiled rapidly in vacuo 
to the crystallizing density. If in a sirup the molecules of sugar are 
brought sufficiently near to each other through concentration—the 
removal of the dissolving liquid—these molecules attract each other 
so strongly as to overcome the separating power of the solvent, and 
they unite to form crystals. Sugar is much more soluble at high 
than at low temperatures, the heat acting in this as in almost all 
cases as a repulsive forceamong themolecules. Itis therefore neces- 
sary to maintain a high vacuum in order to boil at a low pressure 
in boiling to grain. When the proper density is reached the crys- 
tals sometimes fail to appear, and afresh portion of cold sirup is al-' 
lowed to enter the pan. This must not be sufficient in amount to 
reduce the density of the contents of the pan below that at which 
