THE FARMER AT HOME. 417 



teenth of its weight, but other barks only a thirtieth or fortieth. Four 

 pounds of good oak bark make one pound of leather ; but one pound 

 of catechu, or earth brought from Bengal, is equal to eight pounds of 

 oak bark. By an immersion into tan liquor, which is an infusion of 

 bark, the combination of the tannin with the organized gelatine, which 

 forms the animal fibre, is slowly established ; and the compound of 

 tannin and gelatine not being soluble in water, and not liable to 

 putrefaction, the skin is rendered dense and impermeable, and not 

 subject to spontaneous change, which it would otherwise soon undergo. 

 To render it equal throughout the whole substance of the skin, the 

 action of the tan liquor must be gradual ; and hence the tanning is 

 performed by successive immersions of the skin in liquors of different 

 strength. Sir H. Davy observes, that leather slowly tanned in weak 

 infusions of bark, appears to be of better quality, being both softer and 

 stronger than when tanned by dense infusions ; and he ascribes this to 

 the extractive matter which they imbibe. 



TANNING. The preparation of skins, by means of which they 

 are rendered into leather. The first part of this preparation consists 

 in taking off the hair, which is effected by steeping in lime water. 

 When this is done and everything superfluous is removed with the 

 knife and the pumice, as in the preparation of parchment, the skin is 

 put into the tan ; that is. being stretched in a pit, it is covered with 

 tan, and the pit filled with water. At Hunter, Greene county, New 

 York, tanning has been carried on very extensively. The tannery 

 has seven powerful water wheels, adapted to its various machinery. 

 In one year, of which we have its statistics before us, 26,360 sides of 

 sole leather were tanned in this establishment. They weighed 

 637,413 pounds, and were manufactured with the labor of forty-nine 

 hands, and with 3,200 cords of bark. 



TAPIOCA. This is an excellent article, well known in domestic 

 economy, obtained from the farina of the roots of an American plant 

 called Mandioc and Cassiva, and is used for puddings and other light 

 food for invalids. Bread is also made from it. The plant is indigen- 

 ous in tropical America, and is cultivated from Florida to Magellan, 

 and in several countries of Asia and Africa. The stem is smooth 

 and branching, and rises to the height of six or seven feet. It is 

 easily cultivated, grows rapidly, and produces abundantly. The roots 

 attain the size of a man's thigh, shaped somewhat like a parsnip ; 

 and two years are required to bring it to perfection.^ Every part of 

 the plant is filled with a milky juice, which is a very violent and 

 dangerous poison, bringing on death in a few minutes if swallowed ; 

 and it may well excite surprise that human ingenuity should have 

 converted the roots into an article of food. The flour made from these 

 roots, when kept free from moisture, continues good for fifteen or twenty 

 years. It is very nutritious, half a pound a day being sufficient for 

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