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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![B. EEAGENTS IN THE DRY WAY. I. Eluxes. II. Blowpipe Eeagents. The more important reagents and those in general use are described in the following sections; special reagents employed in isolated cases will be noticed when their use is considered. A. REAGENTS IN THE WET WAY. I.—Simple Solvents. Simple solvents are liquids which do not enter into chemical combi- nation with the substances dissolved in them; they will accordingly dissolve any quantity of matter up to a certain limit, which is called the point of saturation, and is in a measure dependent on the tempera- ture of the solvent. The essential and characteristic properties of the dissolved substances (taste, reaction, colour, &c.) are not destroyed by the solvent. (See § 2.) J J § 20. Water, HO [H^O]. Preparation.—Pure water is obtained by distilling spring water from a copper still with a head and worm of pure tin, or from a glass retort, although the latter is not so good; about one-fourth should be left in_ the_ retort. If the distilled water is to be quite free from carbomc acid and carbonate of ammonia, the portions passing over &vst must be thrown away. In the larger chemical and in most pharma- ceutical laboratories, the distilled water required is obtained from the steam apparatus which serves for drying, heating, boihng, &c. Eain water collected m the open air may in many cases be substituted for ■distilled water, * res«5.—It must be colourless, odourless, and tasteless, and should not leave the smallest residue when evaporated in a platinum vessel. It should not be changed by sulphide of ammonium (copper, lead, iron) nor rendered turbid by baryta water (carbonic acid). No cloudiness should be produced even after long standing with addition of oxalate of ammoma (lime), chloride of barium and hydrochloric acid (sulphuric acid), nitrate of silver and nitric acid (chlorides). It should give no blue coloration with iodide of potassium, starch-paste and dilute sul- phuric acid (nitrous acid), and no yellow coloration with Nessler test (ammonia). Uses.—W^terf is used principally as a simple solvent for a great variety of substances; most conveniently from the wash-bottle (seep 9 fig. 3), which affords a ready means of applying the water in a thicker or thinner stream as desired. A special use for it is in the decom- position of certain neutral metaUic salts (such as terchloride of antimony Sta\ieK;S cLrXtl?^ '^'^ -g-- -atter, see t In analytical experiments distilled water only is used ; whenever therpfnrP the term water occurs in the present work, distilled water iVmeS ' D 2](https://iiif.wellcomecollection.org/image/b21966953_0059.jp2/full/800%2C/0/default.jpg)
