168 CORRESPONDENCE OF RAY. 



marine or muriatic salt, an essential salt or nitre of plants, 

 and also a fixed alkali salt. I have seen great varieties 

 of fermentations produced, by pom*ing the same acid 

 spirit upon many several fixed salts prepared and purified 

 all alike. Their sapors do very sensibly difier in solu- 

 tions ; and you cannot make aurum fulminans with so 

 small a quantity of any fixed salt as that of tartar. I do 

 conclude, therefore, against you and Mr. Daniel Cox, 

 that fixed salts do really difier in qualities and accidents. 

 However, I submit to yom- excellent judgment, and I will 

 not be positive in this or the other controversy. 



London, May 9,-85. 



Mr. Eay to Dr. Eobinson. 



Sir, — Yours of May 9 came to hand last post, wherein 

 you produce good authority for what you affirm concern- 

 ing the mutual transmutation of vegetable principles, or 

 immediate component particles, whereto I can say no- 

 thing, unless I had the author's books you cite ; and 

 perhaps not then neither, unless I should repeat the 

 experiments myself. 



But that there are fixed and physically indivisible 

 principles in nature I thus argue : 



If there be no such, but bodies are infinitely divisible, 

 how can there be any constancy in generations or pro- 

 ductions ? 



Why are there not infinite new concrete and mixed 

 bodies daily produced, and as many lost ? 



For if bodies be infinitely divisible, figures being in- 

 finite, the particles whereunto they are divided must pro- 

 bably be of infinite figures, and few alike ; and why 

 should those of the same figure convene ? 



How come bodies to be divisible, even by fire, into 

 great numbers of parts, either really homogeneous, or 

 seemingly so, and not rather into infinite varieties of par- 



