§ 93. QUxVNTITATIVE METHODS. 157 



hydrochloric acid, remove any great excess of acid by 

 evaporation, and j^recipitate the solution with sodic car- 

 bonate. (§ 53.) 



Heat the iSltrate from the precipitate by chlorine as lon<T^ 

 as any odor of the gas is perceived. 



D. Precipitation of llme^ CaO^ and magnesia^ ^IgO^ 

 in the filtrate from the precipitate by sodic acetate (A) or 

 by chlorine (C). ^N'eutralize the solution with ammonia if 

 it is acid, and proceed as directed in § 50 5 to precipitate 

 lime Avith ammonic oxalate, and magnesia with hydric 

 disodic phosphate. 



M Separation and determination of sulphuric acid 

 {anhydride)^ SO^. Precipitate the acid with baric chlo- 

 ride in the slightest possible excess, and preserve the 

 Avashings with water alone, while those with cupric acetate 

 may be thrown away. (§ 59.) 



JF". Estimation of phosphoric acid (anhydride), P^O^^ 

 in the filtrate from the precipitate by baric chloride. 



Add ammonia in slight excess only, if much iron or 

 aluminum is present, otherwise a mixture of ammonia and 

 ammonic carbonate, as long as a precipitate is formed, 

 digest the mixture a considerable time until the free am- 

 monia is expelled, wash the precipitate well, dissolve it, 

 without drying it, in nitric acid, and eliminate PjO^ with 

 ammonic molybdate. (§ 61. b.) 



G. Elimination of the cdkaline metals as chlorides. 



(1.) Precipitate SO3 by the slightest possible excess of 

 baric chloride, if this has not already been done ; evapo- 

 rate the mixture on the water-bath until most of the free 

 acid has been removed, add pure milk of lime in slight 

 excess, digest some time on the water-bath, and filter out 

 the precipitated Fe^Og A\0^ MgO, and, SO3 and P^O,. 

 Wash the precipitate as long as the washings make argentic 

 nitrate turbid, precipitate the excess of lime in the concen- 

 trated filtrate and washings, by ammonic carbonate con- 



