Set.II. Agriculture and Vegetation. 139 



the properties of nitre. This is the cafe 

 with the carduus benedictus, wild cucum-r 

 ber, and pellitory. Bcildue, in 1734, has 

 a paper in the academy of fciences, where 

 he fays, that he extracted real nitre from a 

 decoction of bourache, efpecially when he 

 added fome quick-lime to it, to fix the oily 

 particles the better, that the falts might 

 cryftallife. He fays, that a mould which 

 formed itfelf on this decoction, after it had 

 been kept for fome time, burnt lilce oil and 

 nitre. But all this is no proof, J:hat the 

 nitre comes from the vegetables ufed jn 

 the making nitre j for all kind of vege- 

 tables do equally well, even thofe which 

 contain a vitriolic fait. Befides no fixed 

 fait is ever got from putrefied vegetables, or 

 from any animal fubftance, which Lemery 

 feems to have forgot. It is furprifing, that 

 a chymift fhould fall into fo great an error. 

 Thefe vegetables and animal fubftances; 

 act, as we mall foon fee, in a very different: 

 way, by affording an abforbent earth, and 

 yolatile alkaline fait, and fo increafing the 



matri?c 



