[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

THE DOUBLE EFFECT EVAPORATORS.

These consist of two large closed pans provided within with steam pipes of copper, whereby the liquid is heated.  They are also connected with each other and with pumps in such a way as to reduce the pressure in the first to about three fifths and in the second to about one fifth the normal atmospheric pressure.

The juice boils rapidly in the first at somewhat below the temperature of boiling water, and in the second at a still lower temperature.  The exhaust steam from the engines is used for heating the first pan, and the vapor from the boiling juice in the first pan is hot enough to do all the boiling in the second, and is taken into the copper pipes of the second for this purpose.  In this way the evaporation is effected without so great expenditure of fuel as is necessary in open pans, or in single effect vacuum pans, and the deleterious influences of long continued high temperature on the crystallizing powers of the sugar are avoided.

From the double effects the sirup is stored in tanks ready to be taken into the strike pan, where the sugar is crystallized.

THE FIRST CHANCE TO PAUSE.

At this point the juice has just reached a condition in which it will keep.  From the moment the cane is cut in the fields until now, every delay is liable to entail loss of sugar by inversion.  After the water is 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