170 MADDER 



tiful purple colour. This solution gives again with an excess of acid a yellow, floccu- 

 lent precipitate, which, after filtration, dissolves almost entirely in boiling alcohol, 

 and the solution on evaporation affords needle-shaped crystals of pure alizarine, mixed 

 with white masses of fat acid. The latter, therefore, seems to occupy the place taken 

 up by the impurities before the treatment with soap. This experiment serves also to 

 prove that it is alizarine which forms the basis of the more permanent colours 

 afforded by madder, though, on the other hand, as in dyeing the finer madder 

 colours, it cannot be denied that the colouring-matters which are removed by the 

 treatment with soap and acids contribute to the effect produced in dyeing ordinary 

 madder colours. 



The same result is attained in dyeing Turkey red, but the process employed is 

 somewhat different and much more complicated. See TCHKEY RED. 



The attempts which have been made at various times to obtain an extract of madder, 

 capable of being applied in making so-called steam-colours for calico and other 

 fabrics, have not been completely successful. A very beautiful pink has been pro- 

 duced by Gastard and Girardin, in France, by printing on calico, previously prepared 

 with some mordant, an ammoniacal solution of an extract of madder called colorine, 

 but it is not much superior, either as regards its hue or its degree of permanency, to 

 what can be obtained by easier processes from dye-woods and other materials. 



Madder is not so much employed in woollen dyeing, especially in this country, as in 

 cotton dyeing and printing. Only ordinary woollen goods are dyed red with madder, 

 since the colour is not so bright as that obtained from cochineal or lac, though it is 

 more permanent and cheaper. A mixture of alum and tartar is employed as a mordant. 

 The addition of a little muriate of tin in dyeing imparts to the colour a more scarlet 

 tinge. The bath of madder, at the rate of from 8 or 16 o'unces to the pound of cloth, is 

 heated to such a degree as to be just bearable by the hand, and the goods are then 

 dyed by the wince, without heating the bath more until the colouring matter is fixed. 

 Vitalis prescribes as a mordant, $th of alum and ^th of tartar ; and for dyeing Jrd of 

 madder, with the addition of ^jth of solution of tin, diluted with its weight of water. 

 He raises the temperature in 'the space of one hour to 200, and afterwards he boils 

 for three or four minutes, a circumstance which is believed to contribute to the fixation 

 of the colour. The bath, after dyeing, appears to contain much yellow colouring- 

 matter. Sometimes a little archil is added to the madder, in order to give the dye a 

 pink tinge ; but the effect is not lasting. By passing the goods after dyeing through 

 weak alkali, the colour acquires a blueish tinge. By adding other dye-stuffs, such as 

 fustic, peachwood, and logwood, to the madder in dyeing, various shades of brown, 

 drab, &c., are obtained. Madder is also used in conjunction with woad and indigo in 

 dyeing woollen goods blue, in order to impart to the colour a reddish tinge. See 

 INDIGO. 



Silk is seldom dyed with madder, because cochineal affords brighter tints. 



Preparations of Madder. The numerous analytical investigations of madder, 

 undertaken chiefly in consequence of the Sociite Industrielle de Mulhouse having 

 offered in the year 1826 a premium for a means of discovering the real quantity of 

 colouring-matter in the root, and of determining the comparative value of different 

 samples of madder, led to many attempts on the part of chemists to improve the 

 quality of this dye-stuff by means of chemical agents, and thus render it more fit for 

 the purposes to which it is applied. Eobiquet and Persoz were the first to point out 

 the advantages which result from submitting madder, previous to its being used, to 

 the action of strong acids. They showed that, by acting on madder with strong 

 sulphuric acid, and then carefully washing out the acid with water, a product was 

 obtained which not only possessed a greater tinctorial power than the original 

 material, but also dyed much brighter colours. This important discovery, which was 

 not, like so many others, arrived at by chance, but was purely the result of scientific 

 investigation, did not at first receive, on the part of practical men, the appreciation 

 which it deserved. The product obtained by the action of sulphuric acid on madder, 

 which in the first instance was called charbon sulfurique, afterwards garancine, was 

 first manufactured on a large scale by MM. Lagier and Thomas, of Avignon, but so 

 great were the prejudices entertained by dyers and calico-printers against its use at 

 the commencement, that years elapsed before they could be overcome ; indeed they 

 were partly justified by the imperfect nature of the product itself. The persevering 

 efforts to improve the method of manufacture, and adapt it to the wants of the con- 

 sumer were at last attended with success, so that at the present day garancine has 

 come to be used to as great an extent as madder, and large quantities of it are now 

 manufactured in France and other countries. 



It was supposed by Eobiquet, that by the action of sulphuric acid on madder the 

 saccharine, mucilaginous, and extractive matters of the root were destroyed, and thus 

 hindered from producing any injurious effects in dyeing, and that the woody fibre 



