304 VEGETABLE SUBSTANCES. 



the public, must of necessity act as checks upon future 

 experiment and improvement. It will be seen, when 

 treating- of some of the substances used in dyeing, 

 how much the imposition of absurd restrictions, gene- 

 rally arising from unfounded prejudices, has prevailed 

 among most European governments, and tended 

 only to shackle the art, and to retain it in that state 

 of ignorance of theoretical principles which kept it so 

 long in its infancy. 



The French government afforded, however, a 

 countervailing advantage, by offering particular re- 

 wards for definite desiderata ; and subsequently by 

 appointing the most, eminent chemists of France, in 

 succession, to superintend and elevate the practice of 

 the arts connected with chemistry, and more especially 

 the art of dyeing. Accordingly that country became 

 superior to the rest of Europe in this pursuit, and 

 made great arid striking improvements during the 

 whole of the last century. 



The practice of dyeing has been carried on for many 

 years in England with tolerable success ; but until 

 recently very little progress has been made in investi- 

 gating the theory on which the practice was founded. 

 The Royal Society, soon after its institution in 

 1662, called the attention of some of its members to 

 this subject ; but it was not until many years after 

 this recommendation was issued, that Lewis wrote 

 his valuable remarks on dyeing. These were con- 

 fined to only a few processes ; but at length, towards 

 the close of the last century, the works of Delaval, 

 Henry, and Dr. Bancroft, besides many other excel- 

 lent essays, rescued the English from the disgrace of 

 borrowing wholly from the French all improvements 

 in the art ; and since that period the progress of the 

 theory, as well as of the practice of dyeing, has been 

 rapid in this country. 



Dr, Bancroft distinguishes dyeing substances into 



