In the experiments at Fort Scott in 1886, much difficulty was
experienced on account of inversion of the sugar in the diffusion
battery. The report shows that this resulted from the use of soured cane
and from delays in the operation of the battery on account of the
imperfect working of the cutting and elevating machinery, much of which
was there experimental. Under the circumstances, however, it became a
matter of the gravest importance to find a method of preventing this
inversion without in any manner interfering with the other processes. On
the suggestion of Prof. Swenson, a portion of freshly precipitated
carbonate of lime was placed with the chips in each cell.[1] In the
case of soured cane, this took up the acid which otherwise produced
inversion. In case no harmful acids were present, this chalk was
entirely inactive. Soured canes are not desirable to work under any
circumstances, and should be rejected by the chemist, and not allowed to
enter the factory. So, also, delays on account of imperfect machinery
are disastrous to profitable manufacturing, and must be avoided. But for
those who desired to experiment with deteriorated canes and untried
cutting machines, the addition of the calcium carbonate provides against
disastrous results which would otherwise be inevitable.
[Footnote 1: For this improvement Prof. Swenson obtained a patent
Oct. 11, 1887, the grant of which was recently made the subject
of congressional inquiry.]
Immediately after it is drawn from the diffusion battery the juice is
taken from the measuring tanks into the defecating tanks or pans. These
are large, deep vessels, provided with copper steam coils in the bottom
for the purpose of heating the juice. Sufficient milk of lime is added
here to nearly or quite neutralize the acids in the juice, the test
being made with litmus paper. The juice is brought to the boiling point,
and as much of the scum is removed as can be taken quickly. The scum is
returned to the diffusion cells, and the juice is sent by a pump to the
top of the building, where it is boiled and thoroughly skimmed. These
skimmings are also returned to the diffusion cells.
This method of disposing of the skimmings was suggested by Mr.
Parkinson. It is better than the old plan of throwing them away to
decompose and create a stench about the factory. Probably a better
method would be to pass these skimmings through some sort of filter, or,
perhaps better still, to filter the juice and avoid all skimming. After
this last skimming the juice is ready to be boiled down to a thin sirup
in