/// the Isle of Wight. 219 



tlie colour of these precipitates was much paler when the water had 

 not previously been exposed to the atmosphere. 



I. Alkaline solutions produced copious greenish flocculent preci- 

 pitates, which became darker on standing in the air. 



K. Nitrat of silver occasioned a dense, white, but not considerable 

 precipitate. 



L. Both muriat and nitrat of barytes occasioned copious white 

 precipitates. 



M. A piece of marble being boiled for some time in a few ounces 

 of the water, the marble was found to have undergone no sensible 

 loss of weight by that operation j but its surface had acquired a faint 

 yellowish tinge. 



N. A quantity of the water being evaporated to dryness, and a 

 considerable degree of heat applied to the dry residue, a solution of 

 this in water had the same effect of reddening litmus as before. 



§ IV. Inferences arising from those Effects. 



1. From experiment A, connected with experiments C, H, I, M 

 and N, and from the circumstance of taste, and other general pro- 

 perties, it appeared highly probable that the water contained sulphat 

 of iron, and perhaps also sulphat of alumine, without any uncom- 

 bined acid.* 



2. From experiments C and D, it appeared evident that iron and 

 lime were contained in the water, and that their solvent was not 

 carbonic acid.f 



* Solutions of sulphat of iron and sulphat of alumine, though made from these salts 

 in their crystallized state, have, like acids, the power of imparting a red colour to 

 litmus. 



+ The reddish flakes mentioned in C & D, and in § ii, «, are uniformly found to be 

 sub'Sulphat of iron. 



2e2 



