The use of the blowpipe in the examination of minerals, ores, furnace-products, and other metallic combinations / By Professor Plattner ... Translated from the German, with emendations, by Dr. Seridan Muspratt ... With a preface by Professor Liebig.
- Karl Friedrich Plattner
- Date:
- 1845
Licence: Public Domain Mark
Credit: The use of the blowpipe in the examination of minerals, ores, furnace-products, and other metallic combinations / By Professor Plattner ... Translated from the German, with emendations, by Dr. Seridan Muspratt ... With a preface by Professor Liebig. Source: Wellcome Collection.
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![The divergence of the two lines a 6 and a c requires a re- mark. The smaller the divergence is, in general, the less will be the variation in weight for each descending line, and the more accurately the diameters of globules can be com- pared; but this is again limited in practice, for if the diver- gence be so minute that the difference between the diameters of two globules cannot be ascertained, the scale becomes useless. I have found the most convenient divergence to be 2-ths of a line, in a length of 50 English lines.* The value of the scale is considerably increased by mark- ing at the side of each division the per-centage indicated in a metallic globule corresponding to it. For the smallest of these three decimals are sufficient; if, however, the next decimal number exceed 5, the preceding may be increased by 1. A silver globule, when placed upon the scale, is often found not to coincide with any of the perpendicular lines: in this case the distance of the touching point from the upper line is ascertained ; then the difference of weight corresponding to the divisions enclosing the globule, is multiplied into the known fraction, and the product added to the weight indica- ted by the under line. LE. g., if a silver globule, placed at 9-3rds of the distance between 43 and 44, corresponds to a richness of silver comprised between 83°48 and 77-916 loths, or, in decimals, 2°37160 and 2°21545 per cent., the differ- ence of the centesimal value being 0°15615,—this, multiplied by 3, gives 0°10410, which, added to 2°21545, shews the pro- duct to be 2°31955 per cent. The exactness of these calcula- tions depends chiefly on the skill exercised in placing the smallest globules upon the scale, to ascertain their diameters. The operator may however control his results by weighing a number of globules obtained from an ore of a mean value in one lot upon the balance (after measuring them singly upon the scale), and dividing the whole weight by the number of globules taken. 2. Application of the Scale for determining the weights of Gold Globules, obtained in quantitative assayings. It is very easy to comprehend, that upon such a scale as * [The English line is equal to 3:17494 millimetres.]—7Zvrans.](https://iiif.wellcomecollection.org/image/b29334810_0328.jp2/full/800%2C/0/default.jpg)
