g^ PHILOSOPHICAL TRANSACTIONS. [aNNO 1757. 



water appeared more yellowish than formerly, and its surface was almost wholly 

 covered over with the cremor. They both afforded a tincture with galls, which 

 was not sensibly different from what they gave before their exposure. On the 

 1 4th day the water of the under well had precipitated a yellow ochrous sediment, 

 but the other water a more considerable quantity. A large quantity of cremor 

 continued also to swim on the surface of the upper water, but there was very 

 little separated from the water of the under well. Both waters being now tried 

 with galls, instead of the deep blue colour, which they formerly exhibited, they 

 now became only of a deep purple colour. On the 20th day the visible appear- 

 ance of both waters was the same as when last observed. On the 38th day they 

 both afforded as deep a purple colour with galls, as they did 3 weeks before ; and 

 during that time also they had not precipitated any more of their ochrous parts, 

 nor suffered any other sensible alteration. 



The water of the upper well being filtrated from all the ferrugineous matter, 

 which it had separated during these 38 days, was rendered almost as limpid and 

 clear as when newly taken from the well : but being boiled for some time, it be- 

 came of a turbid yellow colour ; and being allowed to stand, it again precipitated 

 abundance of an ochrous sediment ; and being filtrated, and mixed with galls, it 

 received a faint purple colour of a bluish hue. 



Exper. 37. A bottle of the water of each of these springs being carefully 

 sealed, carried to Moffat, and kept for 2 months, suffered not the least alteration 

 during that time, but was as fresh as when immediately taken from the fountain. 

 And he was informed, that after it was carried to Edinburgh, and to places at a 

 greater distance, it kept a much longer time, without being any way spoiled. 



From these observations he thinks it will appear, that this mineral water con- 

 tinues longer entire, and particularly that it retains the quality of tinging with 

 galls longer than most others of the chalybeate kind : at least of a great number 

 which he had seen described, he did not remember one that retained it nearly so 

 long when exposed to the open air. Many of them lose this quality entirely in a 

 few hours ; and it is greatly impaired in the same time, even in those which re- 

 tain it longest. But this water remains exposed to the open air for days, with 

 scarcely any alteration. This might perhaps be owing either to the larger pro- 

 portion of ferrugineous parts, with which it is impregnated ; to their being at- 

 tenuated to a greater degree; or to their more perfect commixture with the 

 water, by means of the aluminous salt. The longer time that any mineral water 

 remains entire, without any separation of its mineral parts ; or the longer it 

 retains the same form, which it has when newly taken from the spring ; the more 

 perfect is the commixture of these parts with their fluid vehicle : and he believed 

 on that account would be more effectual for medicinal uses : for which reason 



