44 



Methods of estimating accurately 



by silver, to ascertain the muriatic acid. The quantity of it will most 

 likely be imponderable, and there is no method known by which 

 its separation from the chlorine can be well effected. 



Iodine, if present in appreciable quantity, may be precipitated as 

 protiodide of copper by adding a solution of 1 part of sulphate of 

 copper, mixed with 2£ parts of proto- sulphate of iron. 



To estimate the bases of the salts contained in the water, a portion 

 of it is concentrated by evaporation, a little nitric acid having 

 been previously added with the double view of retaining in solution 

 the* earthy carbonates, and of peroxidizing the iron. Should its 

 saline contents be great, it must not, however, be much concentrated. 

 It is now rendered acidulous by muriatic acid in proportion to 

 the quantity of lime and magnesia it is supposed to contain, and an 

 excess of carbonate of ammonia added with constant stirring. The 

 free carbonic acid evolved keeps in solution the lime and magnesia, 

 provided the solution be not too concentrated, while the alumina 

 and peroxide of iron are precipitated and allowed to subside in a 

 closed vial or flask. Or, instead of this, muriate of ammonia is 

 added to retain in solution the magnesia, then aqua ammonia? in a 

 flask or vial which the liquid completely fills, and which is closed to 

 prevent the absorption of carbonic acid from the atmosphere. The 

 alumina and peroxide of iron will thus be separated and subside, 

 while the lime and magnesia are retained. In an open glass 

 carbonate of lime would also precipitate. 



These mixed precipitates may be separated by boiling them in 

 solution of potass, which dissolves the alumina, and leaves the per- 

 oxide of iron. From the potass solution the alumina may be preci- 

 pitated by adding muriate of ammonia, and boiling it for some time. 



The liquid from which the precipitate has been removed is neutra- 

 lised exactly with muriatic acid, and considerably concentrated by 

 boiling. Oxalate of ammonia will now throw down all the lime as 

 oxalate. This is mixed with sulphuric acid and heated to redness, 

 and from the resulting sulphate of lime the quantity of lime is 

 deduced. 



A mixture of carbonate and phosphate of ammonia is now added to 

 the residual fluid. After 24 hours' repose, a precipitation of minute 

 crystalline grains, containing the whole of the magnesia, will be com- 



