TAN 



fused, so as to be more equally spread 

 over the land. If it be true that tiie 

 ammonia found in some plants is 

 chiefly derived from the very small 

 portion discovered in rain water, it 

 follows that a scarcely perceptible 

 impregnation with this salt may have 

 most powerful effects on vegetation. 



" When a farm-yard is situated on 

 a hill, and there are fields or pastures 

 on a lower level, at no great distance 

 from it, the liquid from the tank may 

 be conducted by channels lined with 

 clay, having small sluices to direct 

 the streams to any particular field. 

 It may thus be made to irrigate tem- 

 porarily a considerable surface, which 

 it will greatly enrich. It may be led 

 into the common furrows between 

 the lands, or stitches, in ploughed 

 land, and allowed to soak in them, and 

 then it can be spread with the earth 

 of the furrow, by means of broad 

 shovels, over the growing crops, and 

 ■will greatly invigorate them. This 

 species of irrigation is common in 

 Lombardy, where much ingenuity is 

 shown in the manner in which water 

 is made to flow in small rivulets be- 

 tween the rows of growing vegeta- 

 bles. The water here is supplied by 

 streams, but the same method would 

 distribute the tank liquor with great 

 effect. A very small quantity of this 

 liquor, allowed to How into the main 

 feeder of a water meadow, will soon 

 prove how great effects are produced 

 by impregnations which are scarcely 

 perceptible by chemical analysis. 



"Small as the experience has hith- 

 erto been in this country of the ad- 

 vantages of li(iuid manure tanks, it 

 has sufficiently proved their use to 

 induce every man wlio constructs a 

 farm-yard and erects buildings to take 

 in the tank as an essential part of his 

 plan ; and even if it only collected the 

 refuse fluids which are allowed to run 

 off in conmion sewers from most 

 houses, it would soon repay the cost 

 of its construction, while it rendered 

 the ditches in the neighbourhood less 

 subject to noxious emanations from 

 the corrupted matter which now flows 

 into them." 



TANNER'S BARK. The bark of 

 776 



TAN 



oak, &c., used for tanning ; when ex- 

 hausted it is serviceable to the farm- 

 er and gardener, and may be used 

 in stoves (see Store), or composted 

 with lime and earth, or putrescent 

 manures, into a good coarse manure. 

 Where the quantity is large and the 

 land in good tilth, it may be burned, 

 and the ashes applied at the rate of 

 ten to fifteen bushels the acre, espe- 

 cially to clovers and grass. 



TANNER-S WASTE. The mix- 

 ture of lime and hair, scrapings and 

 trimmings of skins, as well as the 

 fluid of the lime and steeping vats, 

 are all serviceable in composts ; the 

 solids being mixed with earth, char- 

 coal, spent bark, or sawdust, and the 

 fluids being used to moisten the com- 

 post heaps. 



TANNIN. The astringent princi- 

 ple of galls, sumach, catechu, and 

 numerous barks. It is very soluble 

 in water, and possesses the property 

 of uniting with albuminous matters, 

 and forming tanno-gtla/inc, or leather. 

 When separated from the other sub- 

 stances in bark, it is found to be a 

 white, astringent powder, with acid 

 reaction, and known as tannic acid; 

 by the action of moisture and air it 

 absorbs oxygen, and becomes con- 

 verted into the insoluble gallic acid. 

 The formula of tannic acid is Cis 

 H., Og-f-S HO : it is tribasic, and its 

 salts are called tannaies. 



The value of any specimen of bark 

 for tanning and certain dyes is as- 

 certained by the amount of tannic 

 acid they contain. The amount in 

 the following table is from Davy. In 

 480 parts, 



lbs. 



OaV bark contains .... 29 



Spanisli chestnut . . . . 21 



Leicester willow (large) . . 33 



Elm 13 



Common willow (large) . . 11 



Ash .16 



Beech . 10 



Hurse-chestnut 9 



Sycamore ]1 



Lombardy poplar .... 15 



Birch 8 



Hazel 14 



Blackthorn 16 



Ci>|)p)ie oak 32 



Inner rind of oak bark. . . 72 



Oak cut in autumn .... 21 



Larch cut ia autumn ... 8 



