LAB 



LAC 



It exhibits, however, under certain cir- 

 cumstances, a great variety of colours, as 

 blue, green, yellow, red, and brown, in 

 their different shades. It shows, like- 

 wise, spotted and striped delineations. 

 Sometimes the same spot if held in differ- 

 ent directions changes its colour from blue 

 to green, &c. The beautiful colours seldom 

 extend over a whole piece ; in general, 

 they show themselves only in large and 

 smaller spots and patches. Different co- 

 lours are presented, according as the piece 

 is held between the light and the eye, or 

 the eye and the light ' It occurs massive, 

 in blunt edged and rolled pieces. Its 

 principal fracture is shining, passing into 

 splendent. Specific gravity is about 2.7. 

 It runs into a white enamel, with addition 

 before the blow-pipe. The constituent 

 parts are 



Silica 69.5 



Alumina 13 6 



Sulphate of lime 12.0 



Oxide of copper 0.7 



Oxide of iron 0.3 



96.1 



It makes a part of certain kinds of 

 green stone, and is accompanied with 

 mica and shorl, though seldom with iron 

 pyrites. It was originally discovered by 

 the Moravians, in the isla'nd of St. Paul, 

 on the coast of Labrador, where it is still 

 to be met with in plenty, also in some 

 parts of Denmark and Norway, and near 

 the romantic Lake of Baikel in Siberia. 

 It is used for many ornamental pur- 

 poses. 



LABRUS, in natural history, a genus 

 of fishes of the order Thoracici. Generic 

 character: teeth strong and sharp; the 

 grinders sometimes convex and crowded ; 

 lips thick and doubled ; rays of the dor- 

 sal fin in several species prolonged into soft 

 processes ; gill-covers unarmed and scaly: 

 There are ninety-eight species enumerat- 

 ed by Shaw, of which we shall notice 

 merely the following : L. scarus, is about 

 the length of twelve inches, and is found 

 in the Mediterranean in immense shoals. 

 It was well known to the ancients, and 

 highly admired by them, being consider- 

 ed as one of the most luxurious dainties. 

 For a representation of the blue-finned 

 Labrus, see Plate V. fig. 2. 



LABYRINTH, in anatomy, the internal 

 cavity of the ear, so called from sinuosi- 

 ties and windings. See EAR, 



VOL IV. 



LABYRINTH, in gardening, a winding 

 mazy walk between hedges, through a 

 wood or wilderness. The chief aim is to 

 make the walks so perplexed and intri- 

 cate that a person may lose himself in 

 them, and meet with as great a number of 

 disappointments as possible. They are 

 rarely to be met with, except in great 

 and noble gardens, as Versailles, Hamp- 

 ton court, &c. There are* two ways of 

 making them ; the first is with single 

 hedges : this method has been practised 

 in England ; and these may, indeed, be 

 best, where there is but a small spot 

 of ground allowed for making them ; 

 but where there is ground enough the 

 double is most eligible. Those made 

 with double hedges, with a considera- 

 ble thickness of wood between them, 

 are approved as much better than sin- 

 gle ones : this is the manner of making 

 them in France and other places ; of 

 all which that of Versailles is allowed 

 to be the noblest of its kind in the 

 world. It is an error to make them too 

 narrow ; for that makes it necessary to 

 keep the hedges close clipped : but if, ac- 

 cording to the foreign practice, they are 

 made wide, they will not stand in need 

 of it. The walks are made with gravel 

 usually set with horn -beam : the palli- 

 sades ought to be ten, twelve, or four- 

 teen feet high ; the horn-beam should be 

 kept cut, and the walks rolled. 



LAC, gum, in chemistry, is a very sin- 

 gular compound, prepared by the female 

 of a very minute insect, the coccus lacca, 

 found on some trees in the East Indies, 

 particularly the banyan fig The insect 

 is nourished by the tree, fixing itself upon 

 the twigs and extremities of the succu- 

 lent branches, where it deposits its eggs, 

 which it glues to the branch by a red 

 liquid, the outside of which hardens by 

 the air, and serves as a cell for the parent 

 insect. This increases in size, and the 

 young insects at first feed upon the en- 

 closed liquid, and after this is expended, 

 they eat through the coat, leaving a hol- 

 low red resinous bag,which is " stick-lac." 

 The best lac is procured from the pro- 

 vince of Acham, but it is obtained in great 

 plenty on the uncultivated mountains on 

 each side of the Ganges. There are four 

 kinds of lac, viz. " stick-lac," which is 

 lac in its natural state, without any pre- 

 paration ; " seed-lac," which is stick-lac 

 broken into small lumps, awd granulated ; 

 " lump lac," which is seed-lac liquified by 

 fire ; " shell-lac," which is a preparation 

 of the stick-lac. By a number of very ac- 



