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]

A TEXT-BOOK OF ASSAYING.

CHAPTER I.

INTRODUCTORY.

Assaying has for its object the determination of the quantities of those constituents of a material which add to or detract from its value in the arts and manufactures. The methods of assaying are mainly those of analytical chemistry, and are limited by various practical considerations to the determination of the constituents of a small parcel, which is frequently only a few grains, and rarely more than a few ounces, in weight. From these determinations calculations are made, which have reference to a mass of material of, perhaps, hundreds of tons. But in all cases, whether the mass under consideration be large or small, whether the material be obtained by mining, grown, or manufactured, the assayer is supposed to receive a small quantity, called "the sample," which is, or ought to be, the exact counterpart of the mass of material that is being dealt with. The taking and making of this sample is termed "sampling"; and the men whose special work it is to select such samples are "the samplers."