A manual of microchemical analysis / by H. Behrens; with an introductory chapter by John W. Judd.

  • Behrens, Heinrich (Theodor Heinrich), 1842-1905.
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: A manual of microchemical analysis / by H. Behrens; with an introductory chapter by John W. Judd. Source: Wellcome Collection.

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    all the section remains covered except the mineral which has to be tested.1 To the isolated fragment one or more of the following methods of testing may be applied. (1) Taking into consideration the dry methods of analysis, the first place must be given to the ordinary processes of assaying by the blowpipe. The results given with minerals of the heavy metals are of the most satisfactory kind, and are obtained with the greatest facility; and further, as Plattner and others have shown, it is possible to obtain quantitative as well as qualitative results. In distinguish- ing between the ordinary rock-forming minerals, however, ordinary blowpipe tests have only a somewhat restricted application. (2) In 1867 Gustav Rose, and in 1869 Mr. Sorby, pro- posed to employ the study of the crystals formed in saturated blowpipe beads, in which crystallisation has been set up, as a method of microscopical analysis ; and in some cases this method has yielded very interesting and valuable results.2 (3) In 1865 Bunsen devised his method of studying the flame-reactions of minerals; and in 1873 Szabo suggested that when a fragment of a felspar or other silicate is introduced into a Bunsen flame under certain regulated conditions, the degree of coloration of the flame, and the fusibility of the mineral, may be used as means for esti- mating the proportions of potassium, sodium, or lime 1 To prepare the perforated cover-glasses they should be evenly covered on both sides with a thin coating of wax, and a small spot of the covering removed by the heated end of a round-pointed wire. A drop of hydro- fluoric solution being placed on the spot, a hole is soon eaten through the glass. - Monatsber. d. k. Akad. d. Wissensch., Berlin, 1867, pp. 129-147, 450-464 ; Monthly Microscopical Journal, 1869, pp. 347-352.