The Elements of Qualitative Chemical Analysis, vol. 1, parts 1 and 2. / With Special Consideration of the Application of the Laws of Equilibrium and of the Modern Theories of Solution.

by Julius Stieglitz

[591] The group includes phosphate, borate, fluoride, oxalate, silicate, arsenite, arseniate, chromate and tartrate ions.

[592] The ions of the amphoteric acids, arsenic and arsenious acids, and chromate-ion, which is reduced by hydrogen sulphide to chromium-ion, are found in the systematic analysis for metal ions.

[593] The ions of the amphoteric acids, arsenic and arsenious acids, and chromate-ion, which is reduced by hydrogen sulphide to chromium-ion, are found in the systematic analysis for metal ions.

[594] See Fresenius, loc. cit., p. 511, footnote, and p. 520.

[595] Other acid ions which would show the group test—precipitation of a barium salt in a neutral solution—are determined in other groups, as follows: arsenite, arseniate and chromate ions in the group of amphoteric acids, etc. (I); carbonate and silicate ions in the carbonate group (II); and oxalate and tartrate ions in the group of organic acids (VII).

[596] The constants refer to 18°. The subindices are used to distinguish the (unequal) concentrations of the silver-ion and of the halide ions in the different solutions referred to in the text.

[597] Hagar's method. See Fresenius, loc. cit., pp. 356 and 378.

[598] See Fresenius, loc. cit., pp. 356 and 378, for the preparation of the solution and for details of the method, and see Smith, General Inorganic Chemistry, p. 566, as to the nature of the sesqui-carbonate.

[599] They also form complex ions with substances related to ammonia, such as the organic amines.

[600] Ammonium arsenomolybdate is an analogous salt (see Laboratory Manual, Part III). A similar complex acid, phosphotungstic acid, is used in alkaloidal analysis.