Mill installations vary on the different plantations, but the general principle of operation is the same on all.  The first process is the extraction of the juice that carries the sugar.  It is probable that this was originally done in hand mortars.  Next came the passing of the cane between wooden rollers turned by ox power, the rollers standing upright and connected with a projecting shaft or beam to the outer end of which the animal was attached, to plod around and around while the cane was fed between the rollers.  The present system is merely an expansion of that old principle.  At the mill, the stalks are dumped, by carload or by cartload, into a channel through which they are mechanically conveyed to huge rollers, placed horizontally, arranged in pairs or in sets of three, and slowly turned by powerful engines.  The larger mills have a series of these rollers, two, three, or even four sets, the stalks passing from one to another for the expression of every possible drop of the juice, up to the point where the cost of juice extraction exceeds the value of the juice obtained.  The expressed juices are collected in troughs through which they are run to the next operation.  The crushed stalks, then known as bagasse, are conveyed to the huge boilers where they are used as fuel for the generation of the steam required in the various operations, from the feeding and the turning of the rollers, to the device from which the final product, the crystallized sugar, is poured into bags ready for shipment.  All this is a seasonal enterprise.  The cane grows throughout the year, but it begins to ripen in December.  Then the mills start up and run until the rains of the next May or June suspend further operations.  It then becomes impossible to haul the cane over the heavily mired roads from the muddy fields.  Usually, only a few mills begin their work in December, and early June usually sees most of them shut down.  The beginning of the rainy season is not uniform, and there are mills in eastern Cuba that sometimes run into July and even into August.  But the general grinding season may be given as of about five months duration, and busy months they are.  The work goes on night and day.

The next step is the treatment of the juices expressed by the rollers and collected in the troughs that carry it onward.  The operations are highly technical, and different methods are employed in different mills.  The first operation is one of purification.  The juice, as it comes from the rollers, carries such materials as glucose, salts, organic acids, and other impurities, that must be removed.  For this, lime is the principal agent.  The details of it all would be as tedious here as they are complicated in the mill.  The percentages of the different impurities vary with the variation of the soils in which the cane is grown.  The next step, following clarification, is evaporation, the boiling out of a large percentage of the water carried in the juice.  For this purpose,