On Sal Nitrum and Nitro- Aerial Spirit 173 



be dissolved in the said waters, I think the source of 

 the error Ues in the fact that the decoction was made 

 in a vessel, used for such purposes, in which perhaps 

 at some time a fixed salt had been boiled ; so that the 

 solution of the sulphur might be caused by a small 

 portion of the fixed salt with which the vessel was 

 imbued. 



It is generally believed that if silver be immersed in 

 the hot Bath waters it will receive a yellow tinge, just 

 as if it were put into a solution of sulphur ; and hence 

 the common belief that these thermal waters are 

 impregnated with sulphur ; but the contrary of this 

 has been ascertained by experiment. For silver put in 

 the baths does not become at all red or yellow, but 

 rather black. But the error seems to arise from this, 

 that the keepers of the baths are in the habit of 

 tinging and as it were gilding silver coins with a 

 saline-sulphureous mud such as is found everywhere 

 in sewers, and then selling them for a small sum to 

 visitors, as coins coloured by the waters of the baths. 



It should also be noticed here that a certain 

 bituminous mud and a small quantity of common 

 sulphur are usually thrown out along with the gush- 

 ing waters of the thermal springs ; yet these eithe 

 float on the surface of the waters or lie at the bottom, 

 but are in nowise dissolved in the said waters. 



Nor are the said thermal waters impregnated with 

 armoniac salt, as some have supposed ; for if salt of 

 tartar is put into a solution of sal armoniac, the simply 

 saline volatile salt (of which sal armoniac partly 

 consists), released from the fetters of the acid salt with 

 which it was previously united, will instantly rise in 

 vapours and will soon betray its presence by assailing 

 the nostrils which approach it. But this in noway 

 happens with the thermal waters. 



