for it is of so fermentable a nature that in the climate of Porto Rico it will run into fermentation inside of half an hour if the process of clarifying is not commenced.  The pans into which the juice is conducted are pierced like a colander.  The liquor runs through, leaving the refuse matter behind.  It is then forced into tanks by a pump and run to the clarifiers, which are large kettles heated by steam.  Lime is used to assist the clarification.  It is then filtered into vats filled with bone black.  The filtering is repeated until the juice changes color, when it is conveyed to the vacuum pans.  It has now become a thick sirup.  It is then pumped into the sirup clarifiers, skimmed, and again run through bone black, and finally is conducted into another kettle, where it is allowed to crystallize.  The sirup that fails to crystallize is molasses, and it is here that we catch up with what we started after.  To extract the molasses from the crystallized mass of sugar, we must go to the purging house.  This is similar to the building spoken of in connection with the simpler process.  It is of two stories.  The upper floor is merely a series of strong frames with apertures for funnel-shaped cylinders.  The sugar is brought into the purging house in great pans, which are placed over the funnels.  The pans are pierced with holes through which the molasses drains off into troughs which are underneath the floor, all running to a main trough.  From thence the molasses runs into vats, called bocoyes, each of which holds from 1,200 to 1,500 gallons.  The hogsheads in which the molasses is brought to this country are manufactured principally in Philadelphia and taken to the West Indies.  They are placed in the hold of the vessel and the molasses pumped into them.  The government standard for molasses is 56 degrees polarization.  When not above that test, the duty is four cents per gallon.  Above it the duty is eight cents.  This tends to keep molasses pure, as the addition of glucose increases the quantity of sugar and therefore of the polarization, and would make necessary the payment of increased duties.  The adulteration of molasses is therefore largely if not wholly done after it is out of bond and in the hands of the jobber.

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PRIMITIVE IRON MANUFACTURE.

We are indebted for the illustrations and the particulars to Dr. Percy’s invaluable book on iron and steel (probably it is not saying too much to describe it as the best work on the subject ever written).

[Illustration:  SECTION OF INDIAN BLAST FURNACE AND BLOWING MACHINE.]