An introduction to the study of chemistry / by Ira Remsen.

  • Ira Remsen
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the study of chemistry / by Ira Remsen. Source: Wellcome Collection.

    30/410 (page 14)
    mand. Most of the rocks met with are also quite comple:^^ and it is a diflBcult matter to isolate the constituents. If we look at a piece of coarse-grained granite we see plainly enough that it contains different things mixed together, and if it be broken up we can pick out pieces of different sub- stances from the mass. If we now examine a piece of each of the different substances thus picked out of the granite, it appears to be homogeneous, i.e., we cannot recognize the presence of more than one kind of thing in any one piece. If the piece is carefully selected it may be powdered finely in an agate mortar, and some of the powder examined with a microscope without the presence of more than one substance being recognized. We are able to isolate three substances from granite by simply breaking it up and pick- ing out pieces of different kinds. We might therefore con- clude that granite consists of three substances. This is true, but it is not the whole truth. For it is possible by proper means to get simpler substances from each of the three already separated. This, however, is a much more difficult process than the separation first accomplished. To effect the separation of eaeh of the three constituents of granite into its elements requires more powerful means. Substances must be brought in contact with them which act upon them, changing their composition, i, e., act chem- ically upon them, and high heat must be used to aid the action. By hard and skilful work it is possible to separate the three components of granite into their elements. Expeeiment 6.—The teacher should provide a piece of coarse-grained granite, and ask the students to separate the three components and to note the differences between them. One of the pieces should then be pulverized and some of the powder put on the slide of a microscope, and each stu- dent asked to examine the powder.