376 MUREXIDE 



hour's boiling the fire is to be removed, and the whole allowed to repose until clear. 

 The bright liquid having been syphoned off from the residue, the latter is to be treated 

 with 120 gallons more water and 6 Ibs. of soda; 2 Ibs. of slaked lime are also to be 

 added in the same manner as in the first operation. The lime is for the purpose of 

 removing extractive matter, and it has been found that it does not do to use it in any 

 other manner than that described. If the soda and lime be allowed to react upon the 

 guano residue at the same time, urate of lime is formed, which, owing to its compara- 

 tive insolubility, causes much trouble in the subsequent operations. 



The two alkaline fluids containing the urate of soda are to be precipitated while 

 warm by a moderate excess of hydrochloric acid. The precipitated uric acid is then 

 to be washed with water and dried. 



Conversion of Uric Acid into Murexide by Brauris Process. In the first place a 

 very large bath of cold water must be provided, having a number of earthenware 

 basins floating upon it. Into each of these basins 2Jth Ibs. of nitric acid are to be 

 poured, the strength of the acid being 36 Beaume. One pound and three quarters 

 of the uric acid, prepared as above, is now to be added by very small quantities at a 

 time. If the temperature rises above 90 F. the whole is to be allowed to cool before 

 adding amy more uric acid. If the water in the bath be so cold that the temperature 

 falls so lew as to stop the reaction, it may be set up again by adding warm water tc 

 the bath, or, more conveniently, by sending some steam into it for a short time. At 

 first the uric acid need only be added to the nitric acid by sprinkling it on the surface ; 

 towards the end of the operation, when the nitric acid has become enfeebled, it is 

 necessary to stir it in. The quantity of mixture co'ntained in two basins is now to be 

 placed in an enamelled iron pot on a sand-bath. As the heat increases the fluid will 

 boil up in the pot, and to prevent loss the vessel must be removed from the fire for a 

 short time. The heating is to be repeated in this manner until the temperature rises 

 to 248 F., and, after removing the pot to the coolest part of the sand-bath, half a 

 pound of liquid ammonia is to be stirred in quickly. In a few minutes the whole is 

 converted into what is called in commerce by the name of Murexide en pate. To 

 convert this into the purer product known as Murexide enpoudre, it is to be repeatedly 

 stirred up with water and filtered, to remove the saline and extractive matters. 



In dyeing cotton by means of murexide, it is necessary to use lead and mercury as 

 mordants. Lauth's process consists in fixing oxide of lead upon the fibre by first 

 immersing it in a bath of acetate of lead, and then in ammonia, or by a bath of oxide 

 of lead and lime. The dye is then mixed with pernitrate or perchloride of mercury 

 and a little acetate of soda, and the cotton goods are worked in it for a sufficient time. 



For printing, the murexide is mixed with thickened nitrate of lead, and the cloth 

 after printing is dried and subsequently passed through a bath, containing 1 00 litres of 

 water, 1 kilogramme of corrosive sublimate, and 1 kilogramme of acetate of soda. 



In Sagar and Schultz's patent process they pad the cotton goods in a solution of 

 murexide with 6 pounds of nitrate of lead in 8 gallons of water, to which when cold 

 6 ounces of corrosive sublimate, dissolved in 2 gallons of water, are added. The goods 

 are dried after dyeing in the above solution, and the colour is fixed by again padding 

 in a solution of wh eaten starch, gum, gum-substitute, or any similar substance. 



Silk may easily be dyed in a bath of murexide mixed with corrosive sublimate. 

 Wool, after being well washed and rinsed, is to be dyed in a strong bath of murexide, 

 and then dried. It is after this to be treated, at a temperature of 104 to 122 F., with 

 a bath containing 60 grammes of corrosive sublimate, 75 grammes of acetate of soda, 

 and 10 litres of water. C. G. W. 



Murexide has now so completely established its place in the arts, that the following 

 notice of it by Dr. Hofmann in his Keport on the Chemical Section of the Exhibition 

 of 1862, forms a very appropriate addendum to Mr. Greville Williams' notice. 



Historical Notice. Since the year 1851 there has appeared on the chemical horizon 

 a rare and beautiful substance, formerly looked upon as a laboratory curiosity, a 

 product to be admired for its brilliant metallic lustre, and for the elegance of its 

 dclioato crystals, but not otherwise important. In consequence, however, of the 

 implication it found in the dyeing and printing of fabrics, it suddenly sprang into great 

 request, and was prepared in extremely large quantities. This substance is murexide, 

 lirst noticed by Prout, but obtained in the state of purity, analysed, and described by 

 MM. Liebig and Wohler, in the admirable paper on Uric Acid and its derivatives. 

 It was destined, however, to have but a brief celebrity. After having shone for some 

 time with great lustre, it was suddenly eclipsed by even more resplendent rivals 

 the gorgeous crimsons, purples, and violets derived from aniline and its homologues. 

 Nevertheless, murexide deserves, for more than one reason, our serious attention ; 

 indeed, it would be difficult to mention a substance whose history is more instructive. 

 Certainly the resources of modern chemistry were never more admirably illustrated 

 than in the promptness with which the sudden demand for raurexide was met ; and 









