352 Analysis of the Hot Springs at Bath. 



what means the carbonate of lime produced this effect, and 

 to what extent it might be employed in rendering infusion 

 of galls a more active re-agent. 



With this intention I boiled some crystallized sulphate of 

 iron in alcohol till nearly the whole of the red sulphate was 

 separated. The remaining quantity being extremely small, 

 I shall consider the iron in this solution as entirely in the 

 state of protoxide. The sulphate, insoluble in alcohol, was 

 dissolved in water, and the quantity of the oxide contained 

 in a given portion of the solution was ascertained by taking 

 the average of two experiments. 



{h) To one ounce of this solution, containing T-Jj-o^dth of 

 a grain of protoxide of iron, infusion of galls was added. 

 This occasioned the usual appearances indicated by the pre- 

 sence of oxide of iron in a very slight degree. The colour 

 produced, increased by the absorption of the oxygen of the 

 atmosphere. 



(i) An equal quantiiv of the solution was treated with 

 prussiate of potash. A light blue colour was immediately- 

 produced by the minute portion of peroxide of iron which 

 had escaped the action of the alcohol : the intensity of this 

 colour was gradually increased by the action of atmospheric 

 air till the iron had arrived at its maximum of oxidizement. 



[k) Infuion of galls was added to one ounce of a dilute 

 solution of carbonate of lime containing -j-^'j^-^-dth of a grain 

 of oxide, as in the former experiments. A red purple colour, 

 of very considerable intensity, was immediately produced. 



(Z) The last experiment was repeated, employing only 

 .j-^-Ljj^dth of a grain of oxide instead of -pJ^-u-dth. A very 

 distinct red purple was immediately produced by the action 

 of the infusion of galls. 



(?«) To one ounce of a solution of carbonate of lime, con- 

 taining -1 o 'o o d th of a grain of oxide, prussiate of potash was 

 added ; but it did not produce any indication of having acted 

 upon the oxide of iron. 



I now prepared a solution of red sulphate of iron by treat- 

 ing the ereen sulphate with nitric acid in a red heat. The 

 quantity of oxi.lc which the solution contained was as in the 



former 



