Mr. Henry's ConftderationSy (^c. 343 



been accurately meafured, they would have agreed 

 fufEciently well with this theory. It is not how- 

 ever confidered as free from objeftions, but by 

 future obfervations muft its truth or fallacy be 

 afcertained : fliould it be found to agree with 

 fuch obfervations, it may throw fome light on the 

 dodlxine of the afcent of vapours, a matter hitherto 

 fo much difputed. 



Considerations relative to the Nature <?/ Wool, 

 Silk, and Cotton, as Objects of the Art of 

 Dying ; on the various Preparations, and 

 Mordants, requifite for thefe different Sub- 

 stances ; and on the Nature and Properties 

 of colouring Matter. Together with fome 

 Observations on the Theory of Dying in 

 general, and particularly the Turkey Red ; by 

 Thomas Henry, F.R.S. and of the Amer. 

 Philof, Society t held at Philadelphia, 



PART FIRST. 



READ DECEMBER 20, X7S6. 



IN the following Memoir, on a fubjeft to 

 which too little attention has been direfled 

 by Englifh writers, my principal intention is to 

 prefent, at one view, the preparatory and other 



Z 4 procefles 



