Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

    53/272 (page 35)
    SOURCES OF ERROR. 30 examine for the members of this group. When he can perform these practical exercises correctly, he may pass on to the second group, performing the experiments given in that table im the same manner. He must deduce from them the method for separating the members of this group from each other, and again test his acquired knowledge by practical exercises. When he thoroughly comprehends the way of separating them from one another, he will find, by the aid of the general table (Chapter ITT), the method to be employed for separating this group from the first. He should then examine various solutions, which may contain all the members of the first. two groups. When he has completed all the basic groups in the manner described, he should analyse about twenty different solutions, and look for all the bases given; after which, the experiments given under the different acids must be performed. The student is then in a condition to go through a complete course of qualitative analysis, commencing with substances already in a state of solution, and concluding with the examination of solids. Both in the solutions and solids. he must look for all the acids and bases treated of in the work. 82. SouRCES OF ERROR.—One frequent source of error with the young analyst has already been noticed, viz., the imperfect mixture of the reagents with the solutions to which they are added. Amnother prolific source of error is the too liberal or the too sparing addition of the reagent, both being objectionable. To show the objectionable nature of a too sparing addition of the reagent, we will suppose the student to be examining a soiution for baryta and lime ; we will further suppose he has added chromate of potash and obtained a precipitate,* which proves the presence of * Whenever a precipitate is obtained, it must be separated from the Guid by filtration, if either the fluid or the precipitate has to be