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.

    219/272 (page 201)
    solid and liquid portions ought in most cases to be examined separately. EXAMINATION OF SOLIDS. PRELIMINARY EXAMINATION OF SOLID SUBSTANCES. 548. The substance is first examined as to its lustre, colour, odour, and whether it is crystalline or amorphous, since these will frequently afford a means of classifying the substance. Thus, a metallic lustre will indicate probably a pure metal or an alloy. A blue colour will indicate the probable presence of some salt of copper; a crystalline structure the probable presence of a salt. 549. The substance is next submitted to the different blowpipe operations described in the table and text. In these experiments, only small quantities of the substance ought to be employed ; for if too much is operated upon, uncertain results are the consequence. A particle the size of a mustard seed is sufficient, and that of the flux added about the size of a hemp seed. In reductions, a larger quantity may be employed, because, in that case, the more metal is produced, the more easily can its nature be ascertained. In all cases it must be reduced to the finest powder. Before entering upon the different operations, we will describe the materials to be employed for the flame of the blowpipe and the substances which are used as sup- ports, referring the student to the article on the blowpipe (55), as to the nature and use of the flame. 550. The flame of the blowpipe-—When coal-gas is available, it is to be preferred, since it is perfectly free from 9§