DURING THE MIDDLE AGE. 133 



cd, by a clue proportion of its conftitucnt prin- 

 ciples. Who then \vill be bold enough to af- 

 fert, that no change can be wrought upon the 

 baler metallic acid, by any additainent however 

 fmall, cither by adding, fubtrading,tranfpoiting, 

 or in any other way, ib that it may be convert- 

 ed into a nobler kind ? 



The opinion that bodies formed by art arc lefs 

 firm and perfect than thofc of the fame kind 

 produced by -nature, is to be received with fomc 

 limitations , as art has given birth to many fub- 

 flances, that agree perfectly in their qualities, 

 with thofe of natural growth. Cannot neutral 

 falts, and fuch like fubfianecs, perfectly ilmilar 

 to thofe that ore native and pure, be prepared by 

 art ? And may not many other bodies likewife? 

 Jffomctimes, indeed, the combination fecms to 

 be rather looter, it is to be afcribcd to the great- 

 er quantity of moifture retained in them, and 

 which natural productions have loll through 

 time. 



From all, then, that has been already faid, it is 

 evident, that the impoflibility of making gold, 

 or tranfmuting metals by art, cannot bedcmon- 

 ftrated : Yet whoever thinks therefore, that the 

 pofiibility is proved, will find himfclf greatly 

 miflakcn. Between two fuch extremes the in- 

 terval is very wide. Or if it be imagined, that 

 any certain conclufion can be drawn a priori, ir 

 will be found, that a. more perfect knowledge 

 I 3 of 



