THEORIES OF DYEING 



By E. A. FISHER, M.A. (Oxon.) 

 Research Department, South-Eastern Agricultural College, Wye, Kent 



From the intensity of their colours many naturally occurring 

 colouring matters would attract very early the attention of 

 primitive man, and among the first signs of intelligence in man 

 would probably be his utilisation of naturally occurring dye- 

 stuffs for purposes of personal adornment. From the application 

 of pigment colours to the human body to the dyeing of fabrics by 

 means of solutions of colouring matters was a step that occurred 

 quite early in human history, and probably no very great 

 period elapsed before dyes were seen to be of two kinds — those 

 which would dye directly (substantive dyes), and those which 

 could be fixed to the fibre only by means of a mordant 

 (adjective dyes). Dyeing is thus very probably the oldest 

 technological process known. It is therefore somewhat sur- 

 prising that though the process of dyeing was brought very early 

 to a high state of perfection, yet it attracted so little attention 

 among scientific workers, that until the latter part of last century 

 no real explanation of the process was put forward. During 

 the last thirty years, however, the whole problem seems to have 

 come suddenly into prominence, and many different theories 

 have been brought forward to explain the phenomena ; each of 

 them supported by evidence that at first sight seems to be 

 perfectly sound, and each of them quickly overthrown by 

 evidence of an equally incontrovertible nature. 



The whole problem, until recently, was in a perfectly chaotic 

 condition, and it is extremely difficult to find a way through, 

 or to bring order into, the vast mass of experimental data that 

 has accumulated during the last few years. The confusion is 

 increased by the fact that the adherents of the various theories 

 seem never seriously to have attempted a rational compromise 

 between their divergent opinions ; one always striving to prove 

 the other theory unsatisfactory or untenable. Such a course 

 could only be justified if it could be proved that all the 



;io 



