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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![§§ 86, 87.] KEACTIONS. SECTION III. BEACTIONS, OR Behaviour of Compounds with Reagents. § 86. In the uitroducfcory remarks, it was stated that the operations and experiments of quahtative analysis have for their object the conversion of the unknown constituents of any given compound into forms pf which we know the behaviour, relations, and properties, affordmg us informa- tion from which we may draw correct inferences regarding the several constituents of which the analysed compound consists. The greater or less value of such analjiiical experiments, hke that of all other inquiries and investigations, depends on the greater or less degree of certainty with which they lead to definite results, no matter whether these are positive or negative. But as a question does not render us any the wiser if we do not know the language in which the answer is given, so, in like manner, analytical investigations will be of no use if we do not understand the mode of expression in which the desired information is conveyed to us; in other words, if we do not know how to interpret the phenomena produced by the action of the reagents on the substance examined. Before we can proceed, therefore, to enter on the practical investiga- tions in analytical chemistry, it is indispensable that we should really have a very accurate knowledge of the behaviour, relations, and pro- perties of the new forms into which we intend to convert the substances we wish to analyse. Now this accurate knowledge consists, in the first place, in a clear conception and comprehension of the conditions neces- sary for the formation of the new compounds, and the manifestation of the various reactions ; and in the second place, in a distinct impression of the colour, form, and physical properties which characterize the new compound. This section of the work demands therefore not only the most careful and attentive study, but requires moreover that the student should examine and verify by actual experiment every fact stated in it. The method usually adopted in elementary works on chemistry is to treat of the various substances and their behaviour with reagents individually and separately, and to point out their characteristic reac- tions. The author, however, in the present work has considered it to be more judicious and better adapted to the tise of the student, to arrange those substances which are in many respects analogous in groups, and thus, by comparing their analogies with their differences, to place the latter in the clearest possible light. A.—Behaviour of the Metallic Oxides and of THEIR Radicles. § 87. Before proceeding to the special study of the several metallic oxides, it will be advisable to give a general view of the whole of them classified in groups, and showing the oxides belonging to each group. The Q 2](https://iiif.wellcomecollection.org/image/b21966953_0107.jp2/full/800%2C/0/default.jpg)
