Footnote 158: Have the convergent lens or condenser lowered and the analyzer out during this test. Footnote 159: The minerals are grouped according to the maximum interference colors given by sections of the thickness of 0.03 mm. Footnote 160: In the case of very small crystals, the centering must be accurate and a cover with a small hole in the center, should be placed over the top of the tube. In this way the eye is brought directly over the axis of the microscope and figures can be observed from very minute crystals. ------------------------------------------------------------------------ TRANSCRIBER’S NOTES Page Changed from Changed to 80 occurs as an alternation product occurs as an alteration product of anhydrite. Gypsum is soluble of anhydrite. Gypsum is soluble in hydrochloric in hydrochloric 136 longer the higher the percentage longer the higher the percentage of calcium in the solution of sodium in the solution ● Typos fixed; non-standard spelling and dialect retained. ● The author used the old chemical symbol (Fl) for Fluorine. ● Corrected the Errata with the exception of the last paragraph "Corrections for mean indices of refraction in Scheme (insert folder)". ● Used numbers for footnotes, placing them all at the end of the last chapter. ● Enclosed italics font in _underscores_. ● Enclosed bold font in ▄lower half block▄. ● The caret (^) serves as a superscript indicator, applicable to individual characters (like 2^d) and even entire phrases (like 1^{st}). ● Subscripts are shown using an underscore (_) with curly braces { }, as in H_{2}O.