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iron cylinders which hold the cast-iron cutlery are exposed to the action of the fire. The several parts may be thus described :
A shows the length and depth of the ash-pit.
K K the iron cylinders as they stand 3 in height in the furnace, the lowermost of which are raised a few inches from the platform by being placed on pieces of brick, the intention of which is to afford the fire access to every part of them. In describing the other parts of this furnace it may be said, that 2 is the dome of the furnace ; 4 is the temporary wall which is built up to close the aperture spoken of in describing the elevation fig. 1, and which in that drawing is marked 4: 5 is one of the holes left at the bottom of the said wall: 7 is another temporary wall of loose bricks; 6 is the space between the two walls; 8 the chimney; 9 an opening in the outer wall, the same width as 4; 10 a cast-iron bearer reaching across the opening to support the front of the chimney.
IPPARATUS FOR BOILING BY MEANS OF THE CIRCULATION OF
HEATED OIL. Fig. 1 is an elevation of the apparatus, which may be thus described :
A is a wrought-iron vessel for heating the oil, similar to the boiler of a steam engine. It is set in brick-work, with a fire under it of a moderate size, and without any flues round the sides, so that the whole action of the fire is upon the bottom. It is made of an oblong form, and its length should exceed its breadth as much as the situation in which it is placed will allow. The size depends upon the quantity of oil to be heated, or the liquor which is to be evaporated, and it is observable that the more the surface presented to the fire exceeds the evaporating surface, the greater will be the economy of fuel. Whale oil, free from sediment, is found to answer better than any other for this purpose, and the quantity necessary to be employed, is merely sufficient to cover the bottom of the vessel to the depth of six or eight inches.
B is a thermometer for ascertaining the heat of the oil.
C is a small tube opening at the lower end into the oil vessel, while the upper extremity passes into a long flue, called a steam vent, and communicating with the atmosphere. This pipe serves three different purposes : the first is, that before the pump begins to work in the morning, there is a quantity of air contained in it, and it is necessary that there should be a vent for that, when the pump is set to work, in order to prevent any compression in the inside of the vessel. The next is, that with a common suction pump it is necessary there should be a communication with the atmosphere. Thirdly, it is designed to carry off the aqueous vapour from the fresh oil, which has a very
bad smell, and such vapours would injure the sugars, if they got abroad in the sugar-house.
D is a cast-iron pump with a spring metallic piston communicating with the oil-vessel A, by means of its suction pipe E. It is set in motion in the usual manner, by some mechanical power.
F is a copper vessel, the bottom of which is covered in the inside by a coil of pipe, communicating at one of its ends with the pump at G, and at the other end with the oil vessel through the pipe H. Through this coil of pipe, the heated oil circulates, and being surrounded on all sides by the liquid in the pan F, it gives out about 100° of its heat in its passage, and returns to the oil vessel to obtain a fresh increase of temperature. This pan is surrounded by brick- or wood-work, to prevent cooling. Of course it has no fire under it.
Fig. 2 is a ground plan of the same apparatus in which the coil of pipe in the evaporating vessel F may be seen.
A is the oil vessel in which are inserted the thermometer B and the vent pipe C. D is the
pump. E, G. The pipes forming the communication between the oil vessel and evaporating pan, which, after circulating in the form of a coil, passes out at the centre of the bottom, and returns to the oil vessel by the pipe H.