148 LUTEOLINE 



potash 2, and nitrate of lead 2 ; or, chlorate of potash 8 parts, bichromate of potash 

 0'5, and sulphide of antimony 8. Wiederhold's mixture, mentioned above, may be 

 made of chlorate of potash 7'8 parts, hyposulphite of lead 2 - 6, and giim-arabic, 1. 



IiUI&ACHEZiZiA, or Fire Marble. This is a dark-brown shelly marble, having 

 brilliant fiery or chatoyant reflections from within. See MABBLE. 



XitriTAR CAUSTIC. A name for nitrate of silver, -when fused and run into 

 cylindrical moulds. 



IiUPINlTfE is a substance of a gummy appearance, so named by M. Cussola, 

 because it was obtained from Lupines. 



IiUPTJIiIWE. The peculiar bitter aromatic principle of the hop, Humulus Lupu- 

 lus. See BEER. 



LUSTRING, sometimes spelled and pronounced Lutestring a peculiar shining 

 silk. 



LUTE (from Lutum, clay ; Lut, Fr. ; Kitte, Beschl'dge, Ger.) is a pasty or loamy 

 matter employed to close the joints of chemical apparatus, or to coat their surfaces, 

 and protect them from the direct action of flame. Lutes differ according to the nature 

 of the vapours which they are destined to confine, and the degree of heat which they 

 are to be exposed to. 



1. Lute of linseed-meal, made into a soft plastic dough with water, and immediately 

 applied pretty thick to junctions of glass, or stoneware, makes them perfectly tight, 

 hardens speedily, resists acids and ammoniacal vapours, as also a moderate degree of 

 heat. It becomes stronger when the meal is kneaded with milk, lime-water, or solu- 

 tion of glue, and is the best lute for fluo-silicic acid. 



2. Lute of thick gum-water, kneaded -with clay, and iron filings, serves well for 

 permanent junctions, as it becomes extremely solid. 



3. By softening in water a piece of thick brown paper, kneading it first with rye- 

 flour paste, and then with some potter's clay, till it acquire the proper consistence, a 

 lute is formed which does not readily crack or scale off. 



4. Lute, consisting of a strong solution of glue kneaded into a dough with new 

 slaked lime, is a powerful cement, and, with the addition of white-of-egg, forms 

 the lute dane a composition adapted to mend broken vessels of porcelain and stone- 

 ware. 



5. Skim-milk cheese, boiled for some time in water, and then triturated into paste 

 "with fresh-slaked lime, forms also a good lute. 



6. Calcined gypsum (plaster-of-Paris), diffused through milk, solution of glue, 

 starch, or gum-water, is a valuable lute in many cases. 



7. A lute made with linseed, melted caoutchouc, and pipe-clay, incorporated into a 

 smooth dough, may be kept long soft when covered in a cellar, and serves admirably 

 to confine acid-vapours. As it does not harden, it may therefore be applied and taken 

 off as often as we please. 



8. Caoutchouc itself, after being melted in a spoon, may be advantageously used for 

 securing joints against chlorine and acid vapours, in emergencies when nothing else 

 would be effectual; or we may use 1 part of caoutchouc dissolved in 2 parts of hot 

 linseed-oil, and worked np with pipe-clay (3 parts) into a plastic mass. It bears the 

 heat at which sulphuric acid boils. 



9. The best lute for joining crucibles inverted into each other is a dough made with 

 a mixture of fresh fire-clay and ground fire-bricks, worked with water. That cement, 

 if made with a solution of borax, answers still better upon some occasions, as it be- 

 comes a compact vitreous mass in the fire. 



LUTEOIiINE is the colouring-principle of the weld (Reseda luteola], a slender 

 plant, growing to the height of about three feet, and cultivated for the use of dyers. 

 When ripe it is cut and dried. 



Chevreul was the first to separate the lutcolinc. It is extracted from the weld by 

 boiling- water, and when this solution is concentrated and allowed to cool, the luteo- 

 line separates ; it is then collected, dried, and submitted to sublimation, when it is 

 condensed in yellow needles. 



It is valued for its durability, and is used as a yellow dye, on cottons principally, 

 and also on silks, but is little used at present. It was formerly used by paper-hanging 

 manufacturers, to form a yellow pigment, but has been entirely superseded for that 

 purpose by quercitron bark and Persian berries. It unites with acids and alkalis, the 

 former making the colour paler, and the latter heightening the colour. The compound 

 which it forms with potash is of a golden colour, becoming greenish when exposed to 

 the air, by absorption of oxygen, and at length becomes red. 



It forms yellow compounds with alum, protochlorule of tin, and acetate of lead ; 

 with the salts of iron it produces a blackish-grey precipitate ; and with sulphate of 

 copper a greenish-brown precipitate. 



It is readily soluble in alcohol and etlior, but sparingly BO in water. H. K. B. 



