THE YOLK OF WOOL. 147 



square inch ; the original coarse wooled breeds have from 5,000 to 

 6,000 fibers on an inch. The twentieth cross of a pure Merino 

 ram upon a coarse wool race had no more than 25,000 fibers to the 

 square inch ; this fact shows very forcibly how long a period 

 it may take to remove the effects of one cross, for if this state- 

 ment be true, the presence of only J /i, 48,687, (less than one mil- 

 lionth part), of impure blood is sufficient to reduce the fineness of 

 the fleece nearly one-half. The yolk which is secreted from the 

 glands of the skin is an alkaline substance, partaking of the char- 

 acter of a soap. At its secretion it is liquid, and in some breeds 

 *)f sheep it remains in this state, moistening and softening the 

 fleece ; in other breeds, particularly some families of the Merinos, 

 the yolk thickens or dries into a sort of gum or wax of an orange 

 yellow color, which adheres to the wool in scales, and greatly adds 

 to its weight. The yolk or "saint" has been found by Dr. 

 Voelcker to consist of a combination of fatty acids with potash, 

 forming a potash soap which is soluble in water. When dried, 

 the yolk contains 59 per cent of fatty compounds, with some nitro- 

 gen, and 41 per cent of mineral matter, of which from 60 to 84 per 

 cent is potash. In some places this potash is profitably recovered 

 from the refuse liquid of wool washings. In November, 1865, 

 Maumene and Rogelet communicated to the Chemical Society of 

 Paris, the details of their experiments on the nature of suiut, 

 which led them to take out a patent for the manufacture of potash 

 salts from this source. They showed that suint is made up of 

 neutral fatty salts containing much potash, but not more than 

 traces of soda, and rarely even that; that the soluble portion 

 yields on evaporation and calcination a mixture consisting mainly 

 of carbonate of potassium, with chloride, sulphate, phosphate, and 

 alumino-silicate of potassium in smaller quantities, also a little 

 lime, magnesia, and oxide of iron and manganese, the average 

 composition being 



Carbonate of potassium 86.78 



Chloride " " 6.18 



Sulphate " " 2.83 



Other substances 4.21 



100.00 



The yolk soluble in water forms from 20 to 22 per cent of the 

 weight of the fleece, and besides this, the fleece contains from 7 to 

 10 per cent of oil, which is not removed in ordinary brook wash- 

 ing unless it be in part dissolved by the action of the supera- 

 bundant potash of the soapy yolk. When the oil and yolk 

 are rempvetf by washing, tie wool becomes harsh an(l dry to 



