104 Rev. Mr Robertson's Analysis of the Water 



redness, weighed one grain and three-tenths, equivalent to .535 

 of a grain of lime. 



The iron was thrown down by ammonia, and dried : it weigh- 

 ed about .04 of a grain. 



From the residual liquid, which contained an excess of am- 

 monia, the magnesia was thrown down by the addition of phos- 

 phate of soda ; the precipitate, dried by a red heat, weighed ex- 

 actly the same on three separate results, being seventeen-twen- 

 tieths of a grain, equivalent to .309 of a grain of magnesia. 



4. Tincture of galls was added to a pint of the recent water. 

 The precipitate, after being calcined in a red heat, weighed 

 three-twentieths of a grain. Being suspected not to be wholly 

 iron, it was redissolved in an acid, and precipitated as in the 

 following process. It then weighed about .05 of a grain. The 

 residual liquid was found to contain a little lime. 



5. The iron in another pint was peroxidised by boiling with 

 nitric acid, the water being considerably concentrated by evapo- 

 ration, and then precipitated by adding to the acidulated solu- 

 tion an excess of carbonate of .soda. It weighed about .05 of a 

 grain. 



The residual liquid being boiled, the lime and magnesia also 

 precipitated in the form of carbonates. Dried by a red heat, 

 they weighed one grain and three-tenths, which, assuming the 

 result in No. 3. to be correct, is three-tenths of a grain less than 

 they should have weighed according to the rules of atomic pro- 

 portion ; but a little of this precipitate was lost in transferring it 

 into the small flask. 



6. Another pint of the water was concentrated by evaporation, 

 the iron peroxidized, and precipitated by ferro-cyanate of potash. 

 As ferro-cyanate of iron it weighed about one-fourth of a grain, 

 equivalent to about .05 of a grain of oxide of iron. 



The iron of another pint was precipitated by a polished piece 

 of zinc, the precipitate redissolved in an acid, and again precipi- 

 tated by a large excess of ammonia, that any zinc present might 

 be retained in solution ; but the precipitate still contained oxide 

 of zinc. 



The precipitation of the peroxide of iron from another pint, 

 by a crystal of carbonate of lime, was only partial after a lapse 

 of three weeks. 



