244 ESSAY XXII. 



this matter from alkali and lixivium sanguinis. The same 

 thing happens if this matter be combined with lime. It is 

 therefore not difficult to separate the vitriolic acid from it. 

 I mixed a little pounded chalk with the distilled water 

 impregnated with this matter, and distilled the mass a 

 second time by a gentle fire. The vitriolic acid united 

 during this process with the chalk, and the colouring matter 

 went over in its greatest purity. In order to hinder as 

 much as possible the escape of this volatile matter through 

 the lute, and in order to prevent the air in the receiver from 

 absorbing too much of it, I make use of a small receiver, 

 pouring a little distilled water into it, and place it so that 

 the greatest part of the receiver, during the operation, shall 

 be immersed in cold water. This matter has a peculiar but 

 not disagreeable smell, a taste somewhat approaching to 

 sweet, and warm in the mouth, at the same time exciting 

 cough. Of its nature and constituent parts, as likewise of 

 its action upon other substances, I shall speak in the second 

 part of this Dissertation. 



