The superiority of the vacuum pan is not universally admitted, and we are told that in France it is superseded by open pans, similar to those called in America "Mape's Evaporators." However this may be, I cannot help believing that the vacuum pan has many decided advantages over all others. One is manifest; the sugar may be grained in the pan, and the granulation is completely under the control of the operator. He may accelerate or retard it at pleasure; he may carry it so far that sugar will not run from the pan, and will have to be taken out of it; he may so conduct the operation as to increase, almost at will, the size and hardness of the crystals. This last is an indispensable requisite if the practice of draining sugar in pneumatic pans should be adopted. The atmospheric pressure is made too powerful for sugars boiled in any other manner; it breaks and destroys the crystals, and in a very few days sets the sugar to fermenting. The pneumatic draining of sugar has many things to recommend it--the usual loss by drainage is avoided, sugar is got ready for market day by day, as it is made, and it may be bleached by pouring white syrup over it and forcing it through the mass. It is said that the process is attended with considerable loss in weight, but as all that drains from the pan may be boiled over once or twice, it is not easy to conceive how the loss can occur. Cane juice contains many ingredients besides sugar, the principal of which are albumen, gluten, gum, starch, resin, wax, coloring matter, and certain salts, all of which, either collectively or individually, have the power of preventing granulation, as may be proved by their addition to a syrup of pure sugar, which will then defy all attempts to make it crystallise. If, therefore, we want to make good sugar, we must endeavour to free our cane juice as much as possible from those substances.