ABACK, or ARRAC, a distilled spirit pre pared from different substances, more espe cially from sweet juice (toddy) extracted from the unexpended flowers of different species of the palm tribe. In Ceylon, where a large quantity of arack is manufactured, it is entirely distilled from cocoa-nut tree toddy. The toddy topes,' or cocoa-nut tree orchards, are very extensive in Ceylon, and their produce is col lected for the distillation of arack, and the manufacture of sugar and oil. • In Ceylon, when it is intended to draw toddy from a tope, the toddy-drawer selects a tree of easy ascent, and connects the upper branches of other trees to it, so as to pass readily from one to another. He ties the flowering spath in different places, and bruises it with the blow of a small mallet ; this is done twice a day for a week ; after which a portion of the spath is cut off, and juice slowly exudes from it. Suc cessive portions of each spath, and successive trees in the tope, are treated in the same way. The juice or toddy is collected in gourds, from which it is emptied into vessels.
Arack may be distilled from toddy the same day it is drawn from the tree, but sometimes this operation is delayed until it becomes sour.
The process of distillation is carried on in the maritime provinces in copper stills, hut in the interior of the island earthen vessels arc chiefly employed. Toddy yields by distillation about one-eighth part of proof-spirit.
On the peninsula of India, arack is distilled from the flowers of two or three different trees. In Java it is made from molasses, palm-wine, and rice. In Turkey it is made from the skins of grapes, flavoured with aniseed ; the moun tain Tartars distil it from many berries and fruits ; cud the Calmucks from milk.
Ceylon exports annually, and for the most part to the presidencies of Bengal, Madras, and Bombay, from 5000 to 6000 leaguers of tweak, each containing 150 gallons. The prime cost of track at Colombo in Ceylon varies from 8d. to 10d. per gallon. Ceylon crack is superior to Batavian crack, and it commonly brings a highor price of from 10 to 15 per cent. on the peninsula of India than Javanese manu factured spirits.
It is said that factitious arack is sometimes sold, made by dissolving flowers of benzoin in pale Jamaica rum. The name of Vauxhall Nectar has been given to this mock :rack. All1E0'METER, is an instrument employed for the purpose of ascertaining the specific gravities of light substances, fluid or solid.
Nicholson's arasometer consists of a hollow copper vessel, from each extremity of which proceeds a stem ; that which, when the instru ment is in a vertical position, is uppermost, is a wire of hardened steel about is inch in diameter, carrying at its top a small cup in which weights may be placed : to the lower stem, which is short, is attached a stirrup carrying a cup in which may be placed a solid body whose specific gravity it may be required to determine. The instrument is so adjusted that if a weight equal to 1000 grains be placed in the upper vessel, the whole will sink in distilled water at a temperature expressed by 60 degrees of Fahrenheit's thermometer, till a mark made on the stem is on a level with the fluid surface. When the specific gravity of a fluid, whether lighter or heavier than water, is to be determined, the instrument is plunged into the fluid, and weights are placed in the upper vessel till the mark on the stem is at the surface.
To obtain the specific gravity of a solid which dons not imbibe water ; the instrument is placed in distilled water, the body is laid in the upper vessel, and weights are added till the mark .on the stern is at the level of the surface ; these weights being subtracted from 1000 grains, leave the weight of the body in air : then, placing the body in the lower vessel, let other weights be added in the upper on o till the mark on the stem is again at the sur face of the water ; these additional weights will express the loss which the body sustains by being immersed in water.
If the substance whose specific gravity is required be, like wood, capable of imbibing water during the experiment, it should be left in the lower vessel, while under water, till the instrument is stationary, when the additional weights in the upper vessel will express the weight of the displaced water together with that which is imbibed ; then, having dried the surface, let the substance be placed in the upper vessel and weighed in air as at first : the difference between this weight and that which was found before the substance was put in the water is the weight of the water im bibed; and this must of course be subtracted from the observed weight of the substance in water, previously to substituting the values of the terms in the last proportion.
The instrument more usually employed to determine specific gravities is the HYDRO ETER.