Analysis of Ike Hot Springs at Bath. 351 



occasioned exactly the same appearance of iron in this as in 

 the water when fresh and hot (X). 



That the action of infusion of galls is lost by the absorp- 

 tion of the oxygen of atmospheric air is proved by the fol- 

 lowing experiment : 



ig) A third quantity of the water was enclosed, with the 

 usual precaution, in a phialj about one-half of which was 

 occupied by the gas evolved from the water in the bath, 

 \vhich has been shown to contain no oxvgen gas. After 

 four days, infusion of galls was added to it^ an^ gave the 

 same appearances of oxide of iron as occur in its application 

 to the fresh hot water. 



Having thus ascertained the effect of oxygen in preventing 

 the action of infusion of galls upon oxide of iron, it remained 

 to be shown in what manner this is effected. I imagined it 

 nnght be produced by increasing the power of combination 

 of the oxide of iron so as to admit of its acting upon the 

 earthy contents of the water and forming compounds, the 

 strong affinity of the constituents of which prevented the 

 action of the infusion of galls. With a view to ascertain 

 how far this supposition was correct, I examined the effects 

 produced by adding carbonate of lime, dissolved by carbonic 

 acid, to solution of sulphate of iron to which infusion of iralls 

 had been previously added ; and although it will appear'^ bv 

 the following experiments, that the alterations produced 

 upon the oxide of iron in the water are caused bv the car- 

 bonate of lime it contains, it will also be found ih.t they 

 are not effected in the way I had supposed. 



A very dilute solution of green sulphate of iron was pre- 

 pared : the quantity of oxide of iron contained in it was so 

 Pmall as scarcely to afford any alteration of colour when in- 

 fusion of galls was added to it ; but upon pourino; solution of 

 carbonate of lime into it after infusion of galls had been 

 added, a deep red colour was almost instantantouslv pro- 

 duced. 



Although this fact did not immediatelv appear likely to 

 solve the difficulties attendant upon the water in que:ition, 

 yet It was sufficiently striking to merit an examination by 



what 



