Lute or Luting. A mixed, tenacious, ductile substance, which being applied between the junctures of distillatory and other vessels, grows solid by drying, and effectually stops up the crevices. Lutes are of different kinds, according to the nature of the operations to be made. When vapours of watery liquors, and such as are not corrosive, are to be contained, it is sufficient to surround the joiner of the receiver to the nose of the alembic, or of the retort, with slips of paper or of linen, covered with flour paste. In such cases also slips of wet bladder are very conveniently used. When more penetrating and dissolving vapours are to be contained, a lute is to be employed of quicklime slacked in the air and beaten into a liquid paste with the whites of eggs. This paste is to be spread upon linen slips, which are to be applied exactly to the joinings of the vessels. This lute is very convenient, easily dries, becomes solid, and sufficiently firm. Of this lute, vessels may be formed hard enough to bear polishing on the wheel.
When acid or corrosive liquors, are to be contained, recourse is had to fat lute; which is made of finely powdered clay, sifted through a fine sieve, and moistened with water; this paste is then well beaten in a mortar with boiled linseed oil, rendered drying by litharge. This lute easily takes and retains the forms given to it. It is generally rolled into cylindrical sticks of a convenient size for use. They are applied by flattening them to the joinings of the vessels, which ought to be perfectly dry, because the least moisture would prevent the lute from adhering. When the joinings are well closed with this fat lute, the whole is to be covered with slips of linen spread with lute of lime, and whites of eggs. These slips are to be fastened with packthread. The second lute is necessary to keep on the fat lute, because this latter remains soft, and does not become solid enough to stick on alone. Fine porcelain clay, mixed with a solution of borax, is well adapted to iron vessels. the part received into an aperture being smeared with it.