LUTES, in chemistry, are substances employed in various operations for closing the joints of apparatus, and especially for connecting retorts. and receivers, so as to prevent the escape either of the vapour or gases generated during distillation or sublimation. The term lute is also applied to the external coating of clay and sand, or other substances, applied to glue retorts, In order that they may support a high tempe rature without fusing or cracking. For operations on the large scale, as the distillation of aquafortis, hydrochloric acid, &c., common plastic clay is a sufficiently good lute. Sometimes it has been recommended to use what la termed fat lute, but this generally only in email distilla tions, as of nitric acid : this lute is prepared by mixing dried and powdered pipe-clay Into a paste with linseed oil ; and the joint is further secured, both where this lute Is used and hi many other cases, by tying it over with moistened bladder.
In most operatione, however, a mixture of pipeclay and meal, as linseed meal or almond powder, is quite sufficient, when secured by bladder, for any purposes, either when acids or ammonia are to be distilled. In luting common stale, in which oils or water are merely
distilled, linseed meal and water, made into a paste, form an effectual lute.
In hating, or rather coating, glans retorts, in order to enable them to sustain high temperatures, Stourloriclge clay or Windsor loam mixed with tow have been used; but they require long drying, and are opt to crack. The simplest mode Is that of brushing the retort over with a paste of pipe-clay and water, sifting sand upon it, drying it quickly In the ash pit of the sand-heat, then covering itaOn with clay and sand, acid repeating the alternate applications And drying till the coating Is judged sufficiently thick.
An excellent lute for these purposes consists of a mixture of Stour bridge clay and asbestos, made into a paste with water.
LUTIf)INE (C,,II,N), an alkaloid Isomeric with tolriclime, found In bone-oil, and also formed during the distillation of cinchonina It le a volatile oily body, lighter than water, and tonna very soluble salts with most of the acids.