refraction of light, by which alone the minute crystals are determined.  The practical operator learns to disregard all other attractions, and to look for the cloud and its peculiarities.  When the contents of the pan have again reached the proper density, another portion of sirup is added.  The sugar which this contains is attracted to the crystals already formed, and goes to enlarge these rather than to form new crystals, provided the first are sufficiently numerous to receive the sugar as rapidly as it can crystallize.

The contents of the pan are repeatedly brought to the proper density, and fresh sirup added as above described until the desired size of grain is obtained, or until the pan is full.  Good management should bring about these two conditions at the same time.  If a sufficient number of crystals has not been started at the beginning of the operation to receive the sugar from the sirup added, a fresh crop of crystals will be started at such time as the crystallization becomes too rapid to be accommodated on the surfaces of the grain already formed.  The older and larger crystals grow more rapidly, by reason of their greater attractive force, than the newer and smaller ones on succeeding additions of sirup, so that the disparity in size will increase as the work proceeds.  This condition is by all means to be avoided, since it entails serious difficulties on the process of separating the sugar from the molasses.  In case this second crop of crystals, called “false grain” or “mush sugar” has appeared, the sugar boiler must act upon his judgment, guided by his experience as to what is to be done.  He may take enough thin sirup into the pan to dissolve all of the crystals and begin again, or, if very skillful, he may so force the growth of the false grain as to bring it up to a size that can be worked.

The completion of the work in the strike pan leaves the sugar mixed with molasses.  This mixture is called malada or masscuite.  It may be drawn off into iron sugar wagons and set in the hot room above mentioned, in which case still more of the sugar which remains in the uncrystallized state generally joins the crystals, somewhat increasing the yield of “first sugars.”  At the proper time these sugar wagons are emptied into a mixing machine, where the mass is brought to a uniform consistency.  If the sugar wagons are not used, the strike pan is emptied directly into the mixer.

THE CENTRIFUGAL MACHINES.

From the mixer the melada is drawn into the centrifugal machines.  These consist, first, of an iron case resembling in form the husk of mill stones.  A spout at the bottom of the husk connects with a molasses tank.  Within this husk is placed a metallic vessel with perforated sides.  This vessel is either mounted or hung on a vertical axis, and is lined with wire cloth.  Having taken a proper portion of the melada into the centrifugal, the operator starts it