PHYSICAL AND LITERARY. 401 



the water ; but a few air-bubbles gather- 

 ed at the bottom of the glafs ; nothing, 

 however, in comparifon of what appeared 

 •when the ol, tart, p. d, was dropt into the 

 fpaw ; and no more than what formed 

 upon dropping oL tart, p, d, into a glafs 

 of pure river- water. 



9. As chalybeate waters, in feveral par- 

 ticulars, referable a folution of vitnolum 

 Martis in water j hence many may have 

 been induced to think, that thofe waters 

 contained a vitriolum Martis^ fuch as is 

 prepared by art: But fome of the lateft, 

 and moft learned authors, as Hoffman, 

 Boerhaave, &c. are of a contrary opinion ; 

 and for a very good reafon, becaufe no 

 vitriolum Martis could ever be found, upon 

 evaporation of chalybeate waters. The 

 experiments, however, made on this fpaw, 

 feem to prove that it contains a fixed vi - 

 triol of iron ; for it not only turns green 

 upon the addition of oh tart. (lo.), but 

 likeways, upon evaporation, there is a fait 

 left which has all the properties of vitri- 

 olum Martis, 



Vol. I, Eee I 



