PROGRESS OP CHEMISTRY IN SOUTH LANCASHIRE. 127 



The liquid is then transferred to an enamelled vessel, diluted with water, and 

 mixed with an excess of carbonate of ammonia when the object is to pro- 

 duce murexide or purpurate of ammonia. Generally, however, carbonate 

 of soda is used, and in this case the product is purpurate of soda. The pre- 

 cipitated murexide or purpurate of soda is separated by filtration, washed 

 and dried. It has the appearance of an amorphous, puce-coloured powder. 

 The quantity manufactured by Mr. Rumney, of Manchester, amounted at 

 one time to 12 cwt. per week, for which about 12 tons of guano were re- 

 quired. The price was at first 305. per lb., but has now fallen to 15s. In 

 printing cotton goods with murexide, nitrate of lead is used as a solvent, the 

 solution properly thickened is printed, and the goods are then passed through 

 a bath of corrosive sublimate. Other methods are employed, but they all 

 depend on the use of salts of lead and mercury. The colour produced by 

 murexide is so brilliant as almost to justify the belief entertained by Liebig 

 and Wohier, that the celebrated Tyrian purple of the ancients was obtained 

 by its means. 



XXIII. Aniline Colours. 



The artificial colouring-matters from aniline and other bases have of late 

 attracted much attention, and various plans have been devised for pro- 

 ducing them. The usual method of obtaining aniline-purple, the so-called 

 " Mauve," consists in submitting salts of aniline in watery solution to 

 the action of oxidizing agents, such as chromates or permanganates, or 

 the peroxides of manganese and lead. To these processes we may add 

 another, patented by Messrs. J. Dale and A. Caro, and carried out in prac- 

 tice by Messrs. Roberts, Dale and Co. This process is based upon the 

 fact that salts of aniline, when heated with solutions of perchloride of 

 copper, completely reduce it to the state of protochloride, with the simul- 

 taneous formation of a black precipitate containing aniline-purple. Messrs. 

 Dale and Caro dissolve one equivalent of a neutral salt of aniline in water, 

 and boil this solution during several hours with a mixture of copper salts 

 and alkaline chlorides corresponding to 6 equivalents of perchloride of 

 copper. After the reaction is completed the mixture is filtered, the black 

 precipitate well washed and dried, and afterwards extracted repeatedly with 

 dilute alcohol in order to dissolve out the colouring-matters, which it con- 

 tains in a remarkably pure state. These manufacturers have also produced 

 aniline-reds by heating anhydrous hydrochlorate of aniline with nitrate of 

 lead at 360° F. The product of this reaction is a bronze-like brittle mass, 

 which contains aniline-red, always accompanied by purple colours. Boiling 

 water extracts the red colouring-matters and separates them from the purple 

 dyes, which after some purification constitute valuable substitutes for the 

 mauve colour. 



The method of fixing these colouring-matters to cotton, invented by 

 Mr. Dale, jun., which promises to be valuable, may be mentioned here. The 

 goods are prepared with a solution of colouring-matter and tannin, and are 

 then passed through a bath containing tartar emetic. The aflSnity of the 

 former substances for antimony determines the fixation of the colour on 

 the fabric. 



XXIV. Disinfectants. 



The manufacture of disinfectants has now become a regular and constant 

 one ; and since the inquiries instituted on the subject by one of us and Mr. 

 M'Dougall of this city, the use of those made in this district has been 

 enormously increased. Mr. M'Dougall manufactures, near Oldham, a disin- 



