124 REPORT 1861. 



district amounts to 300 or 400 tons, that the weekly consumption of the 

 same by printers is about 60 tons, that from 150 to 200 tons are in the same 

 time converted into extracts, and that 150 tons per week of madder are 

 used up, exclusive of what is used for garancine, &c., some idea of the mag- 

 nitude of the interests depending on tlie employment of these materials may 

 be formed. 



The chemistry of colouring-matters is still in its infancy. Indeed, so few 

 of them have as yet been prepared in a state of purity, that we have hitherto 

 been able merely to lay down a few general principles applicable to ail. The 

 direct applications of science in this branch of the arts are therefore few. 

 The purely practical improvements which have been introduced in dyeing 

 and printing within the last twenty years are, however, numerous and im- 

 portant. Among these may be mentioned the invention of steam colours, 

 which certainly dates from an earlier period, but has of late years received a 

 much more extensive application — the improved methods of preparing extracts 

 of dye-woods — the fixation of insoluble pigments on fabrics by means of 

 albumen — the introduction of artificial colouring matters, such as murexide, 

 and the various colours from aniline. 



In the present Report we must, however, confine ourselves to the improve- 

 ments which have been made in the preparation of the materials used for the 

 purpose of dyeing, without entering into the subject of the dyeing-processes 

 themselves. 



No dyeing-material has received so much attention, both on the part of 

 scientific chemists and of practical men, as indigo. The chemical properties 

 of its most important constituent have been fully investigated, and its beha- 

 viour when applied in practice carefully examined. It is perhaps on this 

 very account that we find nothing of importance to report under this head. 

 With the exception of a new method of reducing indigo by means of finely 

 divided metals, patented by Leonard, we do not suppose that any important 

 improvement has been introduced in connexion with this dye-stuff. 



Of no less importance in the art of dyeing is madder, the material with 

 which the most permanent reds, purples, and blacks are produced. The 

 methods which have been proposed for more effectually utilizing this impor- 

 tant dye-stuff are very numerous indeed, though exceedingly few of them 

 have been found to be of practical value. They may be divided into two 

 classes, viz., those having for their object to render available the greatest 

 amount of colouring-matter, and those which tend to produce more perma- 

 nent or more beautiful colours. The first object seems to be perfectly 

 attained by converting the madder by the action of acid into garancine. 

 This preparation is becoming more and more extensively used. There are 

 printing-establishments in which nothing else is employed in the production 

 of madder colours. Even in turkey-red dyeing it is beginning to be much 

 used, thus proving the fallacy of the opinion formerly entertained, that no 

 preparation of madder could be made to supply the place of the crude mate- 

 rial in this process. The garancine for this purpose is manufactured in 

 Holland. It is said to be made by treating the roots with dilute sulphuric 

 acid containing 35 per cent, of the weight of the madder of concentrated 

 acid (the usual proportion in this country being .about 25 per cent.), and 

 boiling for several hours. By this means the pectic acid, one of the most 

 hurtful constituents of the root, is removed. The residue left after the ordi- 

 nary process of madder dyeing still contains a quantity of colouring-matter 

 in a state of combination. By treating it with sulphuric acid a product is 

 obtained called garanceux, which is again used for dyeing. The quantity of 

 garancine manufactured in this district, exclusive of garanceux (which is 



