Q4 PHILOSOPHICAL TRANSACTIONS. [aNNO 1757. 



first. This water was again boiled ; by which means it was again turned a little 

 yellow, by the separation of some more ochre. It was therefore again filtred, 

 and rendered clear, and its aluminous taste was stronger than before. After this 

 filtration, the water was evaporated in a sand-heat to about a l6th part of the 

 original quantity, and then it tasted like a strong solution of alum joined with a 

 small degree of a chalybeate taste. And this being totally evaporated in a glass, 

 there adhered on its sides a pure white salt ; and a larger quantity of the same 

 salt remained m the bottom of the glass, which was not so white, but more im- 

 pure than the former, and of a brown colour. 27. This salt, thus procured from 

 the water, being mixed with distilled vinegar and spirit of vitriol, not the least 

 effervescence was produced. 28. Some of the brown-coloured salt being put on 

 a red-hot iron, it neither sparkled nor decrepitated ; but was turned into a black- 

 ish cineritious substance, which in a short time became a white calx. And though* 

 some of the salt was put upon the iron finely powdered, yet it concreted, and ran 

 together in a cinder, whose cohesion was afterwards destroyed when calcined by a 

 further degree of heat. 2Q. As he was accidentally deprived of the opportunity 

 of obtaining the crystals of this salt, which would have been the best means 

 of knowing to what species it was to be referred ; he dissolved the whole mass 

 in a small quantity of spring-water, and by filtrating this solution, he ob- 

 tained a large proportion of fine earth of a brown colour. 30. This solu- 

 tion of the salt aflx)rded a deep blue tincture with galls. 31. The same solution 

 being mixed with syrup of violets, became of a reddish colour. 32. Saccharum 

 satumi being added to the solution precipitated a thick lactescent cloud. 33. Ol. 

 tart. p. d. being also added to this solution, it caused no visible eflfervescence, yet 

 raised some bubbles of air, and caused a coagulation of many small brown terrene 

 nubeculae in the water ; which, after standing some time, subsided to the bot- 

 tom, and left the water clear. 



These experiments plainly evince (in his opinion), that this water contains an 

 aluminous salt, conjoined with a fine terrene substance, which is probably a part 

 of the matrix, whence the salt has been formed. This salt gave no signs of any 

 alkaline principle ; but on the contrary, of an acidity, as its solution reddens 

 with syrup of violets. With this salt there are also intimately conjoined some 

 very subtile chalybeate parts, which are not separable from it by elixation or 

 evaporation. 



Alum is distinguishable from all other mineral salts, by liquifying and bubbling 

 on a red-hot iron, and turning into a white calx. But this could not be well 

 expected from this aluminous salt, which he had extracted from the water, be- 

 cause it was extremely foul, by being combined with so large a proportion of 

 earth ; which earthy parts were the occasion of turning the salt of a blackish 

 colour upon the iron. However, we see it turns white by a further degree of 



