Cement

(se-menf). Any plastic material capable of becoming hard and of binding together the objects that are contiguous to it; filling-material for the teeth; the crusta petrcsa of the teeth. See Teeth. C.-disc, the glandular disc of orchids. C.-duct, the duct of the cement-gland in cirriped crustaceans. C, Shellac, a cement for sealing microscopic preparations and for making shallow cells. It is prepared by di olving the gum or scales of shellac in about an equal volume of alcohol. Decant or filter the fluid, and to prevent brittlene add to every 50 parts 5 parts each of castor oil and Venetian turpentine.