PREFACE TO THE SIXTH EDITION
The principal changes in this edition are additions to the articles on Gold, Cyanides, and Nickel, and a much enlarged Index. The additional matter covers more than forty pages.
J. J. BERINGER.
Camborne,
January 1900.
PREFACE.
The Text-book now offered to the public has been prepared to meet the existing want of a practical "handy book" for the Assayer.
To mining men the word "assaying" conveys a sufficiently clear meaning, but it is difficult to define. Some writers limit it to the determination of silver and gold, and others imagine that it has only to do with "furnace-work." These limitations are not recognised in practice. In fact, assaying is becoming wider in its scope, and the distinction between "assayers" and "analysts" will in time be difficult to detect. We have endeavoured rather to give what will be of use to the assayer than to cover the ground within the limits of a faulty definition.
At first our intention was to supply a description of those substances only which have a commercial value, but on consideration we have added short accounts of the rarer elements, since they are frequently met with, and occasionally affect the accuracy of an assay.
Under the more important methods we have given the results of a series of experiments showing the effect of varying conditions on the accuracy of the process. Such experiments are often made by assayers, but seldom recorded. Statements like those generally made—that "this or that substance interferes"—are insufficient. It is necessary to know under what conditions and to what extent.
Students learning any particular process cannot do better than repeat such a series of experiments. By this means they will, at the same time, acquire the skill necessary for performing an assay and a confidence in their results based upon work under different conditions.
The electrolytic method of copper assaying given under Copper is a modification of Luckow's; it was introduced by us into the offices of the Rio Tinto Copper Company, and has been in use for many years with success. This modification is now employed in copper-works in Spain, Germany, and England, and is used in place of the dry assay for the commercial valuation of copper ores.
We have adhered to the gram and the "c.c." as the units of weight and volume. Those who prefer working with grains and grain-measures can use the figures given, multiplied by ten. For example:—When 1 gram is mentioned, 10 grains should be used, and 10 grain-measures take the place of 1 "c.c." It is not advisable to mix the two systems, as by using gram weights and grain-measures.
We have intentionally to a large extent omitted to mention the names of those who have originated or modified the various processes. The practice of naming a process after its discoverer has developed of late years, and is becoming objectionable. It is a graceful thing to name a gas-burner after Bunsen, or a condenser after Liebig; but when the practice has developed so far that one is directed to "Finkenerise" a residue, or to use the "Reichert-Meissl-Wollny" process, it is time to stop.
We are indebted to the standard works of Allen, Crookes, Fresenius, Lunge, Michell, Percy, and Sutton, and wish to express our sense of special indebtedness to Mr. Richard Smith, of the Royal School of Mines. One or two of the illustrations are taken from Mr. Sexton's excellent little book on Qualitative Analysis. Our obligation to some others is mentioned in the text.
Finally, we have to thank for assistance in the experimental work Messrs. Bailey, Beswick, Clarke, Grant, Higgins, and Smith.
THE AUTHORS.
Camborne, Nov. 1889.
CONTENTS.
| PART I. | |
| CHAPTER I. | |
| INTRODUCTORY. | |
| Page | |
| Object of assaying | [1] |
| Sampling | [1] |
| Drying: determination of moisture | [5] |
| Calculation and statement of results | [7] |
| Laboratory books and report forms | [9] |
| Quantity to be taken for an assay | [11] |
| Exercises | [14] |
| CHAPTER II. | |
| METHODS OF ASSAYING.—DRY GRAVIMETRIC METHODS. | |
| Methods of assaying | [15] |
| Gravimetric methods | [15] |
| Mechanical separations | [16] |
| Dry assays | [16] |
| (a) Fluxes | [16] |
| (b) Reducing agents | [21] |
| (c) Oxidising agents | [22] |
| (d) Apparatus | [24] |
| CHAPTER III. | |
| WET GRAVIMETRIC METHODS. | |
| Wet gravimetric methods | [27] |
| (a) Solution | [29] |
| (b) Precipitation | [30] |
| (c) Filtration | [31] |
| (d) Drying and igniting | [32] |
| CHAPTER IV. | |
| VOLUMETRIC ASSAYS. | |
| Titrometric assays | [35] |
| (a) Standard solutions | [36] |
| (b) Standardising | [37] |
| (c) Methods of working | [42] |
| (d) Indirect titration | [43] |
| Colorimetric assays | [44] |
| Gasometric assays | [44] |
| CHAPTER V. | |
| WEIGHING AND MEASURING. | |
| Weighing | [47] |
| Measuring liquids | [49] |
| (a) Graduated flasks | [49] |
| (b) Pipettes | [50] |
| (c) Burettes | [51] |
| Measuring gases | [52] |
| CHAPTER VI. | |
| REAGENTS. | |
| Acids, &c. | [54] |
| Bases, salts, &c. | [59] |
| CHAPTER VII. | |
| Formulæ, equations, &c. | [68] |
| CHAPTER VIII. | |
| SPECIFIC GRAVITY. | |
| Introductory | [75] |
| Determination of specific gravity— | |
| (a) Hydrometers | [76] |
| (b) Specific gravity bottles | [78] |
| Calculations depending on specific gravity | [84] |
| PART II. | |
| CHAPTER IX. | |
| SILVER, GOLD, PLATINUM, CYANIDES, MERCURY. | |
| Silver—Detection | [87] |
| Dry assay | [87] |
| (1) Scorification | [88] |
| (2) Pot assays, average ores | [90] |
| " ores with metallic oxides | [91] |
| " ores with metallic sulphides | [91] |
| Explanatory notes on the fusion | [93] |
| The effect of charcoal, flour, &c. | [94] |
| The effect of nitre | [95] |
| The effect of mineral sulphides | [95] |
| (3) Cupellation | [98] |
| The loss of silver | [101] |
| Condition affecting the loss | [102] |
| Methods of correction | [103] |
| Lead required for cupellation | [105] |
| (4) Calculation of the results in ounces to the ton of 2240 lbs. Table | [107] |
| Ores with metallic particles | [108] |
| (5) Explanatory notes | [110] |
| (6) Examples of dry silver assays | [113] |
| Wet assays | [116] |
| Gravimetric method | [117] |
| Gay-Lussac's method | [119] |
| Volhard's method | [121] |
| A modified Gay-Lussac | [123] |
| Volhard's method applied to arsenic | [124] |
| Gold—Detection | [126] |
| Amalgamation assay | [126] |
| Dry assay | [127] |
| (1) Size of charges | [127] |
| (2) Sampling | [127] |
| (3) Assay tons | [131] |
| (4) Small buttons, weighing | [131] |
| " " measuring | [133] |
| (5) Concentration in lead | [136] |
| Quartz ores | [136] |
| Ores with oxide of iron | [138] |
| Ores with metallic sulphides | [139] |
| (6) Cyanide charges, residues, &c. | [140] |
| (7) Cupellation | [142] |
| Cupels | [142] |
| Cupellation temperature | [143] |
| Cupellation loss | [145] |
| (8) Inquartation | [146] |
| (9) Flatting | [149] |
| (10) Parting, in flasks | [151] |
| " in test tubes | [152] |
| " in glazed crucibles | [153] |
| " Loss, &c. | [154] |
| (11) Check assays, surcharge | [154] |
| (12) Bullion assays in special apparatus | [156] |
| Silver, &c., in gold bullion | [157] |
| (13) Sampling of base bullion, &c. | [157] |
| Cyanides—Commercial cyanides | [160] |
| Double cyanides | [161] |
| Prussic acid | [162] |
| Gold-dissolving power of cyanide liquor | [162] |
| Assay for cyanide strength | [163], 165 |
| Assay of commercial cyanide | [167] |
| Alkalinity of cyanides | [167] |
| Acidity of ores | [168] |
| Metals in cyanide liquors | [169] |
| Cyanicides | [169] |
| Platinum | [170] |
| Iridium | [171] |
| Mercury | [171] |
| Dry assay | [172] |
| Wet method | [173] |
| CHAPTER X. | |
| COPPER, LEAD, THALLIUM, BISMUTH, ANTIMONY. | |
| Copper—Introductory | [175] |
| Dry assay | [176] |
| Valuation of copper ores | [181] |
| Wet methods | [183] |
| (1) Electrolytic assay | [184] |
| Volumetric methods | [194] |
| (1) Cyanide method | [194] |
| (2) Iodide method | [199] |
| (3) Colorimetric method | [203] |
| Examination of commercial copper | [205] |
| Lead | [211] |
| Dry assay | [211] |
| Wet assay | [213] |
| (1) Gravimetric method | [213] |
| (2) Volumetric method | [214] |
| (3) Colorimetric method | [218] |
| Thallium | [219] |
| Bismuth | [220] |
| Dry assay | [221] |
| Wet method | [221] |
| (1) Gravimetric determination | [222] |
| (2) Colorimetric assay | [223] |
| Antimony | [225] |
| Dry assay | [225] |
| Wet method | [227] |
| (1) Gravimetric assay | [228] |
| (2) Volumetric method | [229] |
| CHAPTER XI. | |
| IRON, NICKEL, COBALT, ZINC, CADMIUM. | |
| Iron | [231] |
| Gravimetric determination | [233] |
| Permanganate and bichromate methods | [234] |
| Stannous chloride method | [244] |
| Colorimetric determination | [247] |
| Nickel | [251] |
| Dry assay | [251] |
| Electrolytic assay | [254] |
| Titration by cyanide | [255] |
| Cobalt | [259] |
| Zinc | [261] |
| Gravimetric method | [262] |
| Volumetric method | [263] |
| Gasometric method | [266] |
| Cadmium | [269] |
| CHAPTER XII. | |
| TIN, TUNGSTEN, TITANIUM. | |
| Tin | [271] |
| Vanning | [273] |
| Dry assay | [276] |
| Detection, &c. | [279] |
| Gravimetric determination | [281] |
| Volumetric determination | [282] |
| Examples | [284] |
| Titanium | [292] |
| Tungsten | [295] |
| Niobic and Tantalic Oxides | [297] |
| CHAPTER XIII. | |
| MANGANESE, CHROMIUM, ETC. | |
| Manganese | [298] |
| Gravimetric determination | [300] |
| Volumetric determination | [300] |
| Ferrous sulphate assay | [301] |
| Iodine assay | [302] |
| Colorimetric determination | [306] |
| Chromium | [307] |
| Vanadium | [310] |
| Molybdenum | [311] |
| Uranium | [312] |
| CHAPTER XIV. | |
| EARTHS, ALKALINE EARTHS, ALKALIES. | |
| Alumina | [314] |
| Thoria | [317] |
| Zirconia | [317] |
| Cerium | [318] |
| Lanthanum and Didymium | [319] |
| Yttria | [319] |
| Beryllia | [319] |
| Lime | [320] |
| Strontia | [324] |
| Baryta | [326] |
| Magnesia | [328] |
| The Alkalies | [330] |
| Sodium | [334] |
| Potassium | [336] |
| Lithium | [338] |
| Cæsium | [339] |
| Rubidium | [340] |
| Ammonium | [340] |
| PART III. | |
| CHAPTER XV. | |
| OXYGEN AND OXIDES—THE HALOGENS. | |
| Oxygen | [344] |
| Oxides | [345] |
| Water | [350] |
| The Halogens | [358] |
| Chlorine | [359] |
| Bromine | [361] |
| Iodine | [362] |
| Fluorine | [363] |
| CHAPTER XVI. | |
| SULPHUR AND SULPHATES. | |
| Sulphur | [367] |
| Gravimetric determination | [369] |
| Volumetric determination | [370] |
| Sulphates | [377] |
| Selenium | [379] |
| Tellurium | [379] |
| CHAPTER XVII. | |
| ARSENIC, PHOSPHORUS, NITROGEN. | |
| Arsenic | [381] |
| Gravimetric determination | [383] |
| Volumetric method, "iodine" | [384] |
| " " "uranic acetate" | [389] |
| Phosphorus | [394] |
| Gravimetric determination | [396] |
| Volumetric determination | [397] |
| Nitrogen and Nitrates | [400] |
| CHAPTER XVIII. | |
| SILICON, CARBON, BORON. | |
| Silicon and Silicates | [405] |
| Carbon and Carbonates | [414] |
| Coals | [418] |
| Shales | [420] |
| Carbonates | [424] |
| Boron and Borates | [429] |
| APPENDIX A. | |
| Table of atomic weights and other constants | [433] |
| Table for converting degrees of the centigrade thermometer | |
| into degrees of Fahrenheit's scale | [435] |
| Tables showing strengths of aqueous solutions of nitric and hydrochloric acids, | |
| of ammonia and of sulphuric acid | [436] |
| APPENDIX B. | |
| Estimation of small quantities of gold | [440] |
| Practical notes on the iodide process of copper assaying | [441] |
| Method of separating cobalt and nickel | [442] |
| APPENDIX C. | |
| A lecture on the theory of sampling | [444] |
| Index | [450] |