1835.] Madder Dyeing. 457 



edulcorated with pure water. When dried, this precipitate 

 amounts to ^ of an ounce, (IJ loth) and consists of impure 

 madder-purple containing madder-yellow, madder orange, 

 and alumina ; it is somewhat soluble in hot water ; more 

 soluble in spirit. 



In order to separate the madder-purple from all foreign 

 matter, the precipitate should be boiled with much water, 

 and then with dilute muriatic acid, several times, then edul- 

 corated, dried, and boiled with spirit of 85 to 90, and fil- 

 tered while hot. A dark-red solution is thus obtained, 

 which, after evaporation, deposits, on cooling, the madder- 

 purple in the form of an orange-coloured crystalline sub- 

 stance. This is separated by the filter, and is further iso- 

 lated from the mother liquor by solution in spirit, and a 

 second crystallization. Lastly, it should be dissolved in 

 ether, which leaves a brown matter. 



These operations, as may be readily observed, are not 

 intended to be practised by the manufacturer, but they must 

 be attended to in order to obtain the colouring matter in 

 its purest state. 



The great quantity of alum required for the separation 

 of the madder-purple from the madder-root, may be again 

 obtained by evaporating, in lead vessels, the alum solution 

 mixed with sulphuric acid, out of which the madder-purple 

 is precipitated and separated, when the alum separates in 

 crystals. The mother liquor then consists of a solution of 

 alum and sulphuric acid, which will answer again for the 

 precipitation of the madder-purple ; and the alum by cry- 

 stallization, freed from sulphuric acid, may be again em- 

 ployed to take up the madder-purple. By this process the 

 madder-purple is refined. 



( To he continued.) 



Article VII. 



An account of the process of making Spirits, in 

 Great Britain and Ireland.^ 



In giving an account of the processes followed by the dis- 

 tiller in making spirits, it may be necessary to enumerate 

 the vessels and utensils employed in these processes : These 

 are, the mill, mash-tun, coppers, under-backs, coolers, 



* I am indebted for this article to a gentleman of great experience in the 

 manufacture of Spirits. — Edit. 



