Wool scouring takes place at two stages in the process of manufacture into cloth. First, in the raw state, to free the wool from the large amount of grease and dirt it naturally contains; second, after being manufactured into cloth, it is again scoured to free it from the oil that has been added to the scoured raw wool to enable it to spin easily. This oiling is generally known as wool batching, and before the spun yarns or woven fabrics can be dyed it is necessary to remove it. Raw wool is a very impure substance, containing comparatively little wool fibre, rarely more than 50 to 60 per cent. in the cleanest fleeces, while it may be as low as 25 per cent. in the dirtiest. First there is a small quantity of dirt; there is what is called the suint, a kind of soapy matter, which can be removed by washing in hot water. This soap has for its base potash, while its acids are numerous and complex. The wool contains a fatty-like substance of the nature of wax, called cholesterine, and this imparts to the fatty matter, which be extracted from the wool fibre, very peculiar properties. Besides these there are several other bodies of minor importance, all of which have to be removed from the wool before it can be manufactured into cloth. Marker and Schulz give the following analysis of a good sample of (p. 016) raw wool:-- Moisture 23.48 per cent. Wool fat 7.17 " Wool soap (suint), soluble in water 21.13 " Soluble in alcohol 0.35 " Soluble in ether 0.29 " Soluble in dilute hydrochloric acid 1.45 " Wool fibre 43.20 " Dirt 2.93 " ------ 100.00