24 ESSAY II. 



SECTION IV. 



I now come to Mr. Monnet's essay, who maintains, in 

 opposition as well to mine as to Mr. Boullanger's experiments, 

 that fluor mineral contains neither acid nor lime, but that 

 this substance, being volatilised when united with a sufficient 

 quantity of vitriolic acid, forms the acid called fluor acid. 

 The residuum in the retort, or the crystallised salt which I 

 and Mr. Boullanger call selenite, is in his opinion quite a 

 different substance, since both this salt and the crust which 

 is sublimed want only a small quantity of vitriolic acid in 

 order to be changed into fluor acid. Such are the con- 

 clusions of Mr. Monnet. Thus we have a new kind of 

 earth hitherto unknown to chemists, and which will probably 

 remain unknown to them to all eternity. It must be a 

 curious kind of earth which is fixed by itself, but notwith- 

 standing is able, without the assistance of fire, to volatilise 

 the vitriolic acid ; so that both united together form a kind 

 of air, which even retains its elasticity in the cold. If I 

 justly think that fluor acid contains not the least vestige 

 of vitriolic acid, and if all the vitriolic acid made use of for 

 the process is found in the retort after the distillation, 

 united with the basis of the fluor ; and if this basis is lime 

 or pure calcareous earth ; if I shall be able to prove this, 

 I say, Mr. Monnet's theory must fall of itself. 



SECTION V. 



Upon 1 oz. of pure levigated fluor with alcohol, I 

 poured 3 oz. of concentrated acid of vitriol, and distilled 

 the mixture in a sand-bath, having previously put 12 

 oz. of distilled water into the receiver. Then I took 



