SLAG 



parts of logwood of good quality in 600 parts of water ; after which twelve parts of 

 sulphate of iron and two parts of sulphuric acid are added. A sufficient quantity of 

 this solution is introduced into the dye-trough, so as to cover the rollers therein. 

 The solution is kept on the boil by means of the coil of steam-piping placed at the 

 bottom, and the yarn is drawn through the solution, and, passing thence through the 

 chamber containing the ammoniacal vapour on to the drying cylinders, it ends its 

 course on the loom-beam, unless otherwise required. See CALICO-PRINTING. 



SKATES. The fishes comprehended under the .genus Raia. There are many 

 species, the most common being the blue or grey skate, Raia batis. Some of this 

 species weigh as much as 200 Ibs. The thornback, or rough ray, is the Raia clavata ; 

 and the homelyn, or sand ray, Raia miraletus. All three are good eating ; the last is 

 the most common in our markets. 



8Jf.ni. (Peau, Fr. ; Haut, Ger.) The external membrane of animal bodies con- 

 sists of three layers : 1. the epidermis, or scarf-skin (Oberhaut, Ger.) ; 2, the vascular 

 organ, or papillary body, which performs the secretions ; and 3, the true skin 

 (Lederhaut, Ger), of which leather is made. The skin proper, or dermoid substance, 

 is a tissue of innumerable very delicate fibres, crossing each other in every possible 

 direction, with small orifices between them, which are larger on its internal than on 

 its external surface. The conical channels thus produced are not straight, but oblique, 

 and filled with cellular membrane ; they receive vessels and nerves which pass out 

 through the skin (cutis vera), and are distributed upon the secretory organ. The 

 fibrous texture of the skin is composed of the same animal-matter as the serous 

 membranes, the cartilages, and the cellular tissue ; the whole possessing the property 

 of dissolving in boiling water, and being, thereby, converted into glue. The skins of 

 animals are imported for the preparation of furs, for use, and ornament, and for the 

 manufacture of leather. See GLUE, LEATHER, TAN, and FTJBS. 



In 1873 our Imports of skins, furs, and pelts were as follow : 



SXiAG. (Laitier, Fr. ; ScUaclce, Ger.) This is the vitreous mass which covers the 

 fused metal in the smelting-hearths. In the iron-works it is commonly called cinder. 

 Slags consist, in general, of bi-silicates of lime and magnesia, along with the oxides of 

 iron and other metals ; being analogous in composition, and having the same crystalline 

 form in some cases as the mineral pyroxene ; in others as that of oliviiic. 



The following, selected from the analyses of Percy and Forbes, show the composi- 

 tion of the iron-furnace slags : 



