Glue

(glu). A decomposition-product of many nitrogenous animal ti ues. These lose their organized structure, on heating with water, swell up, and gradually go into solution. The solutions, even when very dilute, gelatinize on cooling, forming a jelly that dries to a horny translucent ma . This ma is glue, or gelatin, as the finer grades are termed. It di olves in hot water and forms a liquid po e ing notable cementing-power. Two proximate principles seem to be present as characteristic in all preparations of glue: glut in, obtained chiefly from the hide and larger bones, and chondrin, from the young bones while yet in the soft state, and the cartilages of the ribs and joints. Of these the former much exceeds the latter in adhesive power. Hide-glue is the variety that shows most strongly the adhesive property. Its color may vary considerably without any impairment of its adhesive power. It is usually of a gray to amber or brown yellow color, and translucent or partially opaque. It should be clear, dry, and hard, and po e a gla y fracture. It should swell up but not di olve in cold water, but should di olve in water at 62.50 C.. Cologne Glue is manufactured from scrap-hide which, after liming, is carefully bleached in a chlorid-of-lime bath and then thoroughly washed. Ru ian Glue contains some inorganic admixture. It is of a dirty-white color, and contains from four to eight per cent, of white lead, chalk, zinc-white, or barytes. Size-glue and Parchment-glue are both skin-glues prepared with special care. Bone-glue or Botie-gelatin is a clear product free from offensive odor. It is much used for culinary purposes and for medicinal applications, and for fining or clarifying wines, etc. It is largely in the manufacture of gelatin capsules, of court-plaster, and of gelatin emulsions with bromid and chlorid of silver for coating photographic dry plates. Patent Glue is a very pure variety of boneglue of deep dark-brown color. It is very glo y and swells up very much in water. Isingla , or Fish-gel' a tin, is the finest and best of animal glues. It is pure white, nearly transparent, dry and horny in texture, and free from smell. It di olves in water at from 350 to 500 C. without any residue, and in cooling produces an almost colorle jelly. Liquid Glue.