150 S. G. WALTON. 



sent are more than sufficient to combine with all the 

 carbonic acid present in the salts in solution. 



Permanent hardness— This was found by calculating the 

 sulphates and chlorides of the alkaline earths into their 

 equivalents of calcium carbonate. 



Alkalinity— This figure was obtained by direct titration 

 exactly as described for the estimation of temporary 

 hardness. 



The metals of the Lead, Tin and Zinc groups— 50 litres 

 of the original water were concentrated and evaporated to 

 dryness with hydrochloric acid to render the silica insoluble, 

 taken up with hydrochloric acid, and the filtrate nearly 

 neutralised with ammonia. On treatment with sulphuretted 

 hydrogen and standing, no metallic sulphides separated. 

 To confirm the absence of arsenic, as traces may possibly 

 be volatilised by this treatment, four litres of the original 

 water were concentrated to a small bulk and Gutzeit's test 

 applied, with a negative result. The absence of the metals 

 of the lead and tin groups is thus shown. 



The metals of the iron and zinc groups in the solution 

 from 50 litres through which sulphuretted hydydrogen had 

 been passed, were precipitated by the addition of ammonia 

 and ammonium sulphide, the object of adopting this method 

 of precipitation being to facilitate the filtration of the zinc 

 sulphide. The precipitated sulphides were dissolved in 

 dilute hydrochloric acid and after oxidising with a little 

 nitric acid, the iron and aluminium were precipitated as 

 hydrates in the usual manner ; the operation being carried 

 out three times to insure the removal of all the zinc. The 

 iron and aluminium precipitate was tested for chromium by 

 fusion with sodium carbonate and potassium nitrate and 

 testing the acetic acid solution with lead acetate. No 

 chromium was found. After combining the filtrates from 

 the iron and aluminium precipitates, the solution was con- 



