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 pouring the same acid 

 spirit upon many several fixed salts prepared and purified 

 all alike. Their sapors do very sensibly differ 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 differ in qualities and accidents. 

 However, I submit to your excellent judgment, and I will 

 not be positive in this or the other controversy. 



London, May 9, 85. 



Mr, EAT to Dr. ROBINSON. 



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- 



