Christmas, the hides contain a larger quantity of fat than the alkali of the lime liquor can convert into a soap, and the surplus grease is frequently seen in the finished leather, as it is difficult to remove in later processes. A solution of hyposulphite of soda, or lactic acid, given just before the process of tanning is said to remove the grease, although a slight loss results in the case of those leathers sold by weight. The objection to natural grease in leather can be understood where the latter is intended for colours, but in the case of sole leather it ought not to be a disadvantage, yet, owing merely to the darker appearance of the leather where the grease reaches the grain, its selling value is reduced by 2d. or 3d. per lb. The strange part is that the grain of this sole leather, when made into boots, is buffed on an emery wheel, then sometimes coloured with a paint, and finally sold in boots at the same price as leather free from grease and regular in colour. The liming process in pits takes from six days to a month, according to the character of the leather required. Light calf skins may be ready for unhairing within a week, while hides intended to be finished for "raw hide leather" may be left in the pits quite a month, the object being to distend and harden the fibres. Lamb skins intended for parchment, and small calf skins for vellum, are also subjected to prolonged liming. Between these extremes, there are several stages in the process which have varying effects on the character of the finished leather. In fact, it is a tanner's dictum that leather is made or marred in the lime liquor, though this, of course, only applies to a certain extent. Generally, however, the heavier the hides, the longer the liming required. Fortunately, the limited solubility of the lime in water affords a wide margin of safety in working, and the only danger to guard against is the too prolonged use of old liquors, which are readily detected by the strong odour of ammonia. One important property of lime is its lower solubility in hot than in cold water.