TAPIOCA. [MANDIOC.) TAR is obtained from wood or coal by dis tillation in close vessels, or in piles from which the air is excluded. Pitch is obtained by boiling tar until all the volatile matters are drWen off. Tar is a viscid brown semi-fluid mass, which long preserves its softness. If it be mixed with water, the water acquires a yellow colour and the taste of tar, with slightly acid properties. This solution is well known by the name of tar-water, and has been used in medicine. Tar is soluble in alcohol, in tether, and in the fixed and volatile oils. Oil of tar, creasote, and many other valuable sub stances, are obtained from tar.
Tar is extensively manufactured from the roots and branches of pines and firs in Norway, Sweden, Germany, Russia, North America, and ethos countries in which those trees abound ; but that made in the north of Europe is considered far superior to what is produced in the United States. A conical cavity is made in the ground (generally in the side of a bank or sloping bill), and the roots of the fir, together with lags and billets of the same, being neatly trussed in a stack of the same conical shape, are let into this cavity. The whole is then covered with turf, which is well beaten down. The stack of bil lets is kindled, and a slow combustion of the fir takes place, without flame, as in making charcoal. During this combustion the tar exudes ; and a cast-iron pan being at the bottom of the funnel, with a spout which pro jects through the side of the bank, barrels are placed beneath this spout to collect the fluid as it comes away. As fast as the barrels
are filled, they are bunged, and made ready for exportation.
In some parts of France and Switzerland tar is extracted in a kind of oven or kiln, built of stone or brick in the form of an egg, with its smaller end downwards.
As England requires a large quantity of tar for the navy, the supply from foreign coun tries is an important matter. At different periods the high price of Swedish tar has led to the encouragement by government of the making of tar in the British American colo nies. During the American war, attention was paid to the establishment of the manu facture of tar from pitcoal, an object which had been previously attempted ; but the ma nufacture of coal-tar has not proved so im portant as was at one time anticipated, although for some purposes it is deemed superior to that made from wood. Tar is produced in large quantities in • the manufac ture of coal gas ; but in some districts its value is considered so trifling that it is mixed with the fuel by which the retorts are heated. It is usually separated from the gas by con densation.
The tar imported in the last three years amounted to the following quantities : 1848 12,604) lasts.
1849 15,206 „ 1850 12,006 „ This last named quantity is equivalent to about 5,000,000 gallons. Tar is free from import duty.