364 Mr. Henry's Conftderations on different Materials^ 



The laft confift of metallic calces, and chiefly 

 thofe of iron and copper. 



Of the two former*, moft of their component 

 parts, in which the colouring matter refides, 

 fuch as their mucilage, their gum, and the falts 

 which they contain, are foluble in water ; as, by 

 means of thefe falts, are alfo their oily parts. 

 To thefe the French writers have given the 

 general name of extra6live foapy matter. Other 

 conflituent pares of vegetables are not foluble 

 in water, as fome of their oily, their refinous, 

 and their earthy parts. 



Yet we fhould be deceived, as M. Macquer 

 juftly obferves, if we were to expert to make a 

 perfefb feparation, by means of water, of the ex- 

 traflive foapy matter from the other parts. For, 

 a portion of that matter is defended from the 

 aclion of the water, by the refinous and oily 

 Kibftances ; while, on the other hand, thefe are 

 partially dilTolved, being rendered capable of 

 uniting to the water, by means of the mucila- 

 ginous parts. 



The colouring animal and vegetable drugs of 

 the materia tinSioria have been formed by 

 chemiftry into three divifionsj-. 



I ft. Thofe fubftances, which, together with 

 extractive, contain fome refinous, and alfo, 

 fome portion of earthy, matter in their com- 



* Macquer Diftionairc de Chymic. f Ibid. 



pofition ; 



