THE 



LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



SUPPLEMENT to VOL. XVIIL FOURTH SERIES. 



LXXIV. Critical and Experimental Contribution to the Theory of 

 Dyeing. By Dr. P. A. Bolley, Professor of Technical Che- 

 mistry at the Zurich Polytechnic. 



[With a Plate.] 

 "P^ VER since the first attempts were made by chemists to base 

 -Li on scientific principles the art which is carried to such 

 perfection in this district, two questions have presented them- 

 selves as necessarily requiring solution. 



1. In what part of the coloured fibre is the colouring matter 

 situated ? Does it merely adhere to the surface, or does it pene- 

 trate the entire substance of the cell-walls of such fibres as 

 cotton and flax ? or lastly, in the case of such fibres, is it stored 

 Tip in the interior of the cells ? 



2. What is the nature of the union between the dye and the 

 fibre ? Is it a chemical combination, or is it due to mere surface 

 attraction ? 



It is obvious that the correct decision of the former of these 

 questions must throw much light on the latter ; and this consi- 

 deration suggests the course which it was necessary to take in 

 order to arrive at the required conclusion. Both chemical expe- 

 riments and microscopic observations have been employed on 

 this subject, though neither to any very great extent ; indeed 

 it is only in recent times that researches have been engaged 

 in for the express purpose of ascertaining the true nature of 

 the phsenomena in question : formerly the subject was treated 

 altogether inductively. In this way several theories concerning 

 the process of dyeing have arisen which absolutely contradict each 

 other in all their parts, none of them paying the least regard to 

 the innumerable and ever increasing mass of observations to 

 which a more careful sifting of the facts is daily giving rise. 



It is necessary to give an outline of these various explanations 

 of the dyeing pi-ocess, in order that wc may be able to set forth, 

 without too much repetition, the following verifications of them, 



Phil. May. S. 4. No. 123. Suppl. Vol. 18. 2 I 



