I may tell you that it is not a simple matter, and, moreover, the best classification and arrangement is that one which depends both on the action of the dyes on the fibres, and also on the intrinsic chemical character of the dyestuffs themselves.  Since the higher branches of organic chemistry are involved in the consideration of the structure and dispositions, and consequently more or less of the properties of these dyes, you will readily comprehend that the thorough appreciation and use of that highest and best method of classification, particularly in the case of the coal-tar dyes, will be, more or less, a sealed book except to the student of organic chemistry.  But it may be asked, “How does that highest and best method of classifying the dyestuffs affect the users, the dyers, in their processes?” In reply, I would say, “I believe that the dyer who so understands the chemical principles involved in the processes he carries out, and in the best methods of classifying the dyes as chemical substances, so as to be able to act independently of the prescriptions and recipes given him by the dye manufacturers, and so be master of his own position, will, ceteris paribus, be the most economical and successful dyer.”  Many manufacturers of dyestuffs have said the very same thing to me, but, independently of this, I know it, and can prove it with the greatest ease.  Let me now, by means of an experiment or two, prove to you that at least some classification is necessary to begin with.  So different and varied are the substances used as colouring matters by the dyer, both as regards their chemical and physical properties, that they even act differently towards the same fibre.  I will take four pieces of cotton fabric; three of them are simple white cotton, whilst the fourth cotton piece has had certain metallic salts mixed with thickening substances like gum, printed on it in the form of a pattern, which at present cannot readily be discerned.  We will now observe and note the different action on these pieces of cotton—­(i.) of a Turmeric bath, (ii.) a Magenta bath, and (iii.) a madder or Alizarin bath.  The Turmeric dyes the cotton a fast yellow, the Magenta only stains the cotton crimson, and on washing with water alone, almost every trace of colour is removed again; the madder, however, stains the cotton with no presentable shade of colour at all, produces a brownish-yellow stain, removed at once by a wash in water.  But let us take the printed piece of cotton and dye that in the Alizarin bath, and then we shall discover the conditions for producing colours with such a dyestuff as madder or Alizarin.  Different coloured stripes are produced, and the colours are conditioned by the kind of metallic salts used.  Evidently the way in which, the turmeric dyes the cotton is different from that in which the madder dyes it.  The first is a yellow dyestuff, but it would be hard to assign any one shade or tint to Alizarin as a dyestuff.  In fact Alizarin (the principle of madder) is of itself