68 WRITINGS OF JAMES SMITHSON. 



Possibly this yellow powder, and the crystals of speculary 

 iron which exist in this Vesuvian salt,. have been produced 

 by a natural sublimation of muriate of iron, similar to that 

 of the experiment of the Duke d'AYEN, recorded by Mac- 

 QUER,* and which was known long before to Mr. Boyle and 

 Dr. LEAVis.f 



This Vesuvian salt, considered in its totality, has pre- 

 sented no less than nine distinct species of matters, and a 

 more rigorous investigation, than I was willing to bestow on 

 it, would probably add to their number. 



July 3, 1813. 



A FEW FACTS RELATIVE TO THE COLOURING 

 MATTERS OF SOME VEGETABLES. 



Prom the Philosophical Transactions of the Royal Society of London, 

 Vol. CVIII, p. 110.— Read December 18, 1817. 



I BEGAN, a great many years ago, some researches on the 

 colouring matters of vegetables. From the enquiry being 

 to be prosecuted only at a particular season of the year, the 

 great delicacy of the experiments, and the great care 

 required in them, and consequently the trouble with which 

 they were attended, very little was done. I have now no 

 idea of pursuing the subject. 



In destroying lately the memorandums of the experi- 

 ments which had been made, a few scattered facts were met 

 with which seemed deserving of being preserved. They 

 are here offered, in hopes that they will induce some other 

 person to give extension to an investigation interesting to 

 chemistry and to the art of dying. 



* Did. de Chimie, Art. Fer. ' 



f A course of practical chemistry by William Lewis, 1746, p. 63, note/. 



