If the washing be continued, a less amount of lime is removed in each successive period of time, so that it is evident a point is soon reached at which it becomes a waste of time to continue the washing. In practice this point is reached in about two hours. The progress of the washing is best shown by the curve in the diagram (Fig. 1), in which the ordinates represent the percentage of lime (CaO) in the dry skin, and the abscissæ time in hours. It will be seen that the character of the curve is a hyperbola; such a curve only approaches a line (representing in the example chosen about 1-1/2 per cent. of lime) asymptotically--in other words, it is impossible to wash out all the lime except by an infinite number of changes of water, since each washing removes a less amount than the previous one. The above is a typical case of the washing of limed grains from the splitting machine in the manufacture of skivers. These contain from 4 to 5 per cent. of lime on the dry skin, and, after washing in water in a paddle for six hours, analysis shows them to contain still about from 1·5 per cent. to 1·9 per cent. of lime (CaO).[6] [6] Some further analyses of grains at Trent Bridge gave the following results:-- Water CaO CaO on dry skin Grain from splitting machines 76·3 1·14 4·8 The same after washing 24 hrs. 86·0 0·22 1·57 The same after puering -- -- 0·80 Another grain 79·7 1·06 5·20 The same after deliming as } completely as possible with} -- -- 0·45 HCl } Skin in natural condition 64·0 -- 0·125 M. C. Lamb has found in sheep grains split for skivers the following amounts:-- Ash CaO CaO in Ash Grain from splitting machine 9·3 3·2 34·8 The same after washing 4·1 1·5 35·1 The same after puering 3·1 0·9 29·1 The same after bran drench 1·7 0·55 32·4 The figures are all percentages calculated on the dry weight of the skin. Munro Payne (Tanners’ Year Book, 1905, p. 75) gives the following amounts of lime as Ca(OH)_{2} in limed hides, calculated on dry weight at 212° F.:-- Direct from limes max. 3·859 per cent. " " min. 2·836 " Limed for buff 4·621 " Limed for tanning 3·7659 " Ditto after bating 0·689 " Calf limed 2·601 " Calf bated 0·1215 " Goat limed 5·613 " Goat bated 1·268 "