34 LAMING'S MIXTURE 



XiACUSTRXXTE FORMATION, a geological term. Belonging to a lake. 



IiADANUM. A fragrant gum-resin obtained from several Bpecies of Cistu-?, as 

 C. ladanifcnis and f. Ledon. It is used in Turkey as a perfume. 



LAGAN GOODS. See JETSAM. 



XiAKES. Under this general title are included all those pigments which are pre- 

 pared by combining vegetable or animal colouring matter with earths or metallic oxides. 

 The general method of preparation is to make an infusion of the substance, and to add 

 thereto a solution of common alum ; or sometimes, when it has been necessary to 

 extract the colouring matter by the agency of an acid, a solution of alum saturated 

 with potash. At first, a slight precipitate falls, consisting of alumina and the colouring 

 matter; but if some alkali is added, the precipitate is increased. Some colour- 

 ing matters are brightened by alkalis ; then the decoction of the dye-stuff is made 

 in an alkaline liquor, and being filtered, a solution of alum is poured into it. Where 

 the affinity of the colouring matter for the subsulphate of alumina is great, alumina 

 recently precipitated is agitated with the decoction of the colouring body. The manu- 

 facture of lakes depends on the remarkable property possessed by alumina, of com- 

 bining with, and separating the organic colouring matters from their solutions. 



Bed Lakes. The finest of these is CABMINJS, which, as carminated lakes, called 

 lake of Florence, Paris, or Vienna, is usually prepared by taking the liquor de- 

 canted from the carmine, and adding freshly-precipitated alumina to it. The mixture 

 is warmed a little, briskly agitated, and allowed to settle. Sometimes alum is dissolved 

 in the decoction of cochineal, and then the alumina precipitated by potash ; but the 

 colour is not good when lakes are thus prepared, and to improve it the dyer's solution 

 of tin is often added. A red lake may be prepared from kermes in a similar manner. 



Brazil-wood yields a red lake. The wood is boiled in a proper quantity of water 

 for 15 minutes, and then alum and solution of tin being added, the liquor is to be 

 filtered, and solution of potash poured in as long as it occasions a precipitate. This 

 is separated by a filter, the powder well washed, and being mixed with a little gum- 

 water, made into cakes. Sometimes the Brazil-wood is boiled with vinegar, instead of 

 water. An excess of potash produces a lake of a violet colour, and cream of tartar 

 gives it a brownish hue. 



Madder is much used in the preparation of lakes. 



The following process is recommended : 



Diffuse 2 Ibs. of ground madder in 4 quarts of water, and after a maceration of 10 

 minutes strain and squeeze the grounds in a press. Eepeat this maceration, &c., 

 twice upon the same portion of madder. It will now have a fine rose colour. It 

 must then be mixed with 5 or 6 Ibs. of water and Ib. of bruised alum, and heated 

 upon a water-bath for 3 or 4 hours, with the addition of water, as it evaporates ; after 

 which the whole must be thrown on a filter-cloth. The liquor which passes through 

 is then to be filtered through paper, and precipitated by carbonate of potash. If 

 potash be added in three successive doses, three different lakes will be obtained of 

 diminishing beauty. The precipitates must be washed until the water comes off 

 colourless, then with gum-water made into cakes. 



Yellow Lakes are made with decoctions of Persian or French berries, to which some 

 potash or soda is added ; into the mixture a solution of alum is to be poured so long 

 as any precipitate falls. Quercitron will yield a yellow lake, provided the decoction 

 is purified by either butter-milk or glue. Annotto lake is formed by dissolving this 

 substance in a weak alkaline lye, and adding a solution of alum to the solution. 



Lakes of other colours can be prepared in a 'similar manner ; but true lakes of other 

 colours are not usually manufactured. 



XiATCINABXiE is said of a metal which may be extended by passing between 

 steel or hardened (chilled) cast-iron rollers. 



In the manufacture of rail and bar iron, laminated iron is rolled together at a 

 welding heat, until the required bar or rail is formed (see RAILS). This is, even 

 under the best possible circumstances, a defective manufacture. The union of the 

 bars is never absolutely complete, and the result of the long-continued action of 

 trains of carriages upon all rails is the development of the laminated plates, which 

 frequently^ierf off, layer after layer, to the destruction of the rail, and to the great, 

 danger of the traveller. Railway iron should be rolled into form from perfectly 

 homogeneous masses of metal. This lamination of iron rails has been laid hold of 

 by those who advocate the hypothesis that the slate rocks owe their lamination to 

 mechanical pressure, whereas it is evidently tho result of an imperfect manufacture. 

 See ROLLING MH.LS. 



IiAMING'S MIXTURE. A mixture of porous hydrous peroxide of iron with 

 sawdust, used for absorbing sulphuretted hydrogen in tho purificatioTi of coal-gas. 

 The sulphur accumulated in this mixture may be recovered by calcination, or by 

 means of steam. 



