Licence: Public Domain Mark
Credit: Qualitative chemical analysis / by C. Remigius Fresenius. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![Tests.—Pure sulphuric acid should precipitate the whole of tlie fixed matter from a solution of carbonate of baryta in hydrochloric acid (compare § 36). Uses.—Carbonate of baryta completely decomposes the solutions of certain metallic oxides, such as sesquioxide of iron, or alumina, precipi- tating from them the whole of the oxide as hydrate and basic.salt; there is another class of metalHc salts which is not precipitated by it. It serves, therefore, to separate the former from the latter, and_ affords an excellent means of eflfecting the separation of ferric oxide and alumina from protoxide of manganese, oxide of zinc, lime, magnesia, &c. It must be borne in mind, however, that these oxides must not be present as sulphates, for in that case carbonate of baryta would also precipitate the latter bases from the solution. § 61. 4. Sulphate of Lime, CaO,S03 [CaSOj. Crystallized, CaO,S03 + 2aq [CaS0„2H,0]. Preparation.—VoyfdLQYed. crystallized gypsum (selenite) is digested and shaken with water for some time; the undissolved portion is allowed to subside, and the clear solution is decanted and kept for use. ^565—Sulphate of lime, being a sparingly soluble salt, is_ a con- venient agent in cases where it is wished to apply a solution of a lime salt or of a sulphate of a definite degree of dilution. As a chlute solution of a lime salt, it is used for the detection of oxalic acid ; whilst as a dilute solution of a sulphate it afi'ords an exceUent means of distinguisliing between baryta, strontia, and lime. § 62. 6. Chloride of Calcium, CaCl [CaCl,]. Crystallized, CaCl + 6aq [CaCl,,6H,0]. Preparation.—1 part of crude hydrochloric acid is diluted with G parts of water, and marble or chalk is added to the dilute acid as long as it is dissolved; some hydrate of lime is now added, and then sul- phuretted hydrogen water until a filtered portion of the mixture is no longer altered by sulphide of ammonium. The vessel is covered and allowed to remain at a gentle heat for 12 hours; it is then filtered, the filtrate exactly neutralized, concentrated by evaporation, and left to crystaUize. The crystals are put to drain, and 1 part of the salt is dissolved in 5 parts of water for use. , ,, , ^ rfQsts Solution of chloride of calcium should be perfectly neutral, and neither be coloured nor precipitated by sulphuretted hydrogen or by sulphide of ammonium; it ought not to evolve ammonia when mixed with hydrate of potassa or hydrate of lime. _ _ Uses —In its action and application, chloride of calcium is analogous to chloride of barium. As the latter reagent is used to separate the inorganic acids into groups, in like manner chloride of calcuim^ serves to effect the separation of the organic acids into groups, since it precipi- tates some of them, whilst it forms soluble compounds with otlicrs.](https://iiif.wellcomecollection.org/image/b21966953_0092.jp2/full/800%2C/0/default.jpg)
