Practical dental metallurgy : a text and reference book for students and practitioners of dentistry, embodying the principles of metallurgy, and their application to dentistry, including experiments

Front matter

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Preface To Fifth Edition

At no time in the past, in so far as we have accurate knowledge of the past, has science proven to be of such great value to the world as now. Chemistry and metallurgy have shared with surgery, pathology, mechanics, engineering, and photography, the distinction of being necessary to world progress.

Every person should possess some knowledge of chemistry. The specialist demands a much broader acquaintance with the particular branch of chemistry which concerns his work if he would choose to be of service to his nation. So varied are the problems which depend upon a knowledge of chemical science for their solution, so limitless are the sources of this knowledge, that the average individual must depend upon the reading and study selected for him if he is to obtain but a fair knowledge of its application in his daily life.

In conformity with this idea and knowing that the exactness of science precludes any alteration of facts, the revision of this edition has been made with the view of eliminating obsolete methods of procedure and application and incorporating more recent methods in metallurgy in its application to dentistry or as a basic problem, and yet the fundamental instruction and the pedagogical scheme of the author have been carefully preserved. In a subject of this character the substance is not fully understood without the experimental work and as a result the two have been coupled.

The formation of the four year course in dental schools may give dental metallurgy a different place in

6 PREFACE the curriculum. It is hoped that no less, but rather more time will be devoted to its study under these new conditions.

In this revision, the more important dental, chemical, and metallurgical journals have been consulted together with other reliable sources of information, for which due eredit is given. Association with chemists has broadened our view, and teaching experience has made it possible to add much of interest to the subject which can not be incorporated in the text. Teachers are urged to add collections of stereopticon views of the mining and metallurgical industry, to add interest in a cultural way to the subject. In the end, a knowledge of metallurgy as applied to dentistry is the object sought, and it is hoped that this book may be an aid in imparting such knowledge to those for whom it is intended.

Guy S. MILuBerry.

San Francisco, Cal.

September 1, 1918.

Preface To Fourth Edition

In this edition no effort has been made to change the pedagogie scheme of the author, which has received the endorsement of the teachers in the profession both by personal expression and by the adoption of the text in many of the dental schools since 1897. The subject matter, however, has been thoroughly revised in harmony with the latest information obtainable.

In order to avoid confusion in the mind of the student, the metric system has been used exclusively, all other sys-

PREFACE if tems of weights, measures and temperature having been eliminated, except the troy system in its application to precious metals, as any reform in this regard is obviously impractical.

Data for this revision have been gathered from all sources, including the more recent works on chemistry and metallurgy, but the bulk of the matter has been obtained from the journals of the American. Chemical Society. Wherever possible, full credit has been given for all abstracts.

The pleasure of an intimate friendship with the author, first as a student and later as an associate in teaching, permits me to confirm the prevailing opinion of his qualifications as a teacher, and I trust his work may continue to merit the success which has previously been accorded it.

Guy S. MInuBerry.

San Francisco, Cal.

September, 1911.

FROM PREFACE TO FIRST EDITION

In presenting this little volume to the practitioner and student of the dental profession, the author does not flatter himself that he is filling a void in such literature, or that a crying need has been felt in the profession for this particular production. It has, however, grown out of the exigencies of the writer’s own class-room and laboratory after several years’ practical experience as an instructor on its subject.

8 PREFACE

The endeavor has not been to furnish a scientific and exhaustive treatise on metallurgy, but rather to present, in a clear and practical manner, the principles of that subject as the author sees them related and applicable to the every-day wants of the dentist.

Keenly appreciating the reluctance with which this and the analogous study of chemistry have been pursued by the average student, the author has sought to awaken a deserving interest by doing away with the usual lectures and employing the work as a text book, subject to explanatory elaboration during the recitation; and to further make it so practical that it may be taken into the metallurgical laboratory and used as a manual for practical and experimental work. It presupposes the student to possess a fair knowledge of the principles of inorganic chemistry, comprehending the reading and writing of formulae, atomic affinities, and the expression of equations.

JosePpH D. Hopgen.

Chapter I Introduction

Chemistry, 17; Elements, 17; Metallic Elements, 20; Metallurgy, 20; Ore, 20; Gangue, 20; Slag, 20; Regulus, 21; Speiss, 21; Reduction, 21; Roasting, 22; Calcination, 22; Distillation, 22; Sublimation, 22; Scorification, 22; Occlusion, 22; Cementation, 23; Dry Process, 23; Wet Process, 23; Noble Metals, 24; Base Metals, 24.

Chapter II

PROPERTIES OF METALS Metal, 27; Nontranspareney, 28; Color, 28; Luster, 28; Odor and Taste, 29; Crystalline Form, 29; Malleability, Ductility and Tenacity, 30; Ductility, 30; Tenacity, 30; Elasticity, 34; Sonorousness, 55; Fusibility and Volatility, 35; Specific Heat, 38; Expansibility, 39; Conductivity, 40; Specific Gravity, 43.

Chapter III

Metallic Oxides, 44; Reduction of Metallic Oxides, 48; Metallic Sulphides, 51; Reduction of the Metallic Sulphides, 53; Metallic Chlorides, 56; Reduction of Metallic Chlorides, 57; Metallic Bromides, 58; Reduction of Metallic Bromides, 58; Metallic Iodides, 59; Metallie Fluorides, 59; Metallic Cyanides, 59; Metallic Selenides, 60; Reduction by Electricity, 60.

TIN

Occurrence, 148; Reduction, 148; Properties, 150; Dental Applications, 151; Compounds with Oxygen, 151; Actions of Acids on Tin, 152; Alloys, 153; Tests for Tin in Solution, 157; Electrodeposition of Tin, 157.

Chapter IX

Occurrence, 159; Reduction, 159; Properties, 160; Compounds with Oxygen, 160; Action of Acids on Bismuth, 161; Alloys, 161; Tests for Bismuth in Solution, 166.

CONTENTS . 11 CHAPTER X

ZINC

Occurrence, 167; Reduction, 167; Properties, 168; In the Arts, 170; Dental Applications, 171; Dies, 171; Zine Oxide, 174; Zine Cements, 176; Orthophosphoric Acid, 178; Mixing Cements, 181; Action of Acids en Zine, 184; In Alkalies, 185; Alloys, 185; Test for Zine in Solution, 187.

Chapter XI

CADMIUM Occurrence, 189; Reduction, 189; Properties, 190; Compounds with Oxygen, 190; Actions of Acids on Cadmium, 191; Compounds of Cadmium, 191; Alloys, 191; Tests for Cadmium in Solution, 193.

Chapter XII

Occurrence, 194; Reduction, 196; Properties, 198; Dental Applications, 199; Compounds with Oxygen, 200; Action of Acids on Copper, 200; Alloys, 201; Dental-Amalgam Alloys, 208; Tests for Copper in Solution, 208; Electrodeposition of Copper, 208.

Chapter XIII Iron

Occurrence, 209; Reduction, 211; Electric Furnace Reduction, 215; Properties, 216; Modifications of Iron, 217; Cast Iron, 217; Wrought Iron, 218; Steel, 220; Carburized Iron, 225; Galvanized Iron, 226; Hardening and Tempering Steel, 227; Tempering, 229; Compounds with Oxygen, 231; Action of Acids on Iron, 231; Alloys, 232; Tests for Iron in Solution, 233.

12 CONTENTS

Chapter XX Gold

Occurrence, 296; Mining and Extraction, 301; Dredger Mining, 309; Flotation Process, 310; Cyanide Process, 310; Refining Gold, 312; The Roasting Process, 312; Parting Gold, 315; The Preparation of Chemically Pure Gold, 319; Properties, 324; Gold Beating, 325; Annealing Gold, 330; Properties of Gold Foil, 331; Compounds of Gold with Oxygen, 334; Action of Acids on Gold, 335; Alloys, 337; Gold Plate, 341; Clasp Gold, 343; Crown Gold, 344; Gold Solders, 344; Rules for Computing and Compounding Gold Alloys and Examples, 346; Tests for Gold in Solution, 351; Electrodeposition of Gold, 352.

Chapter XXI

In the Arts, 357; Dental-Amalgam Alloys, 357; A Dental Amalgam, 358; History, 358; Formation of Dental-Amalgam Alloys, 361; Comminution, 363; Ageing, 366; Mercury, 369; Amalgamation, 371; Expansion and Contraction, 373; Spheroiding of Amalgams, 375; Resistance to Stress, 377; Flow, 378; Edge Strength, 380; Discoloration, 380; Conductivity, 381; Washing, 381.

Chapter XXII

A Binary Dental Amalgam, 382; Silver, 382; Tin, 383; Gold, 384; Copper, 384; Platinum, 386; Zinc, 386; Palladium, 386;

14 CONTENTS

Cadmium, 387; Antimony and Bismuth, 388; Ternary Dental Amalgams, 888; Quarternary, Quinary, ete., Dental-Amalgams, 390; Gold, 390; Platinum, 390; Copper, 392; Zine, 392; Bismuth, 393; Aluminum, 393; Analysis of Dental Amalgams, 394; Mercury, 394; Tin, 395; Antimony, 395; Silver, 396; Copper, 396; Cadmium, 296; Zine, 397; Gold, 397; Platinum, 397.

LABORATORY PROCEDURE FOR STUDENTS IN DENTAL METALLURGY

Apparatus Required by Each Student, 400; Assignment of Lockers, 401; Properties of Metals, 401; Compounds of Metals and Nonmetals, 402; Lining Fire Boxes: Handling Crucibles, 404; Electric Furnaces, 405; Metallurgy of Lead, 405; Metallurgy of Tin, 408; Metallurgy of Bismuth, 409; Metailurgy of Zine, 410; Metallurgy of Copper, 412; Metallurgy of Iron, 414; Metallurgy of Aluminum, 415; Metallurgy of Mercury, 416; Metallurgy of Silver, 417; Gold, 419; Amalgam Alloys, 421; Work to be Handed in, 422; Laboratory Reagents, 423; Rules and Suggestions to Students, 425.

ILLUSTRATIONS

FIG. PAGE 1. Hydrogen generate? 7 6. 6! te POO a 2. Sectional view of blast furnace . ... . >; ee eS 3.'Beverberatery furnace ©. Sey ME, oe? ee eae 4, Crucible furnace . . oy APOE es, PA ee aa 5. A small compact blast beieaae se eee SF mere

G;'A. modified type of blast furnace «. *.° re '.. ee 7. Blast furnace for use with gasoline . ....... 80 8. Iron melting pots . . . jis gy a eg 06 rg’ SO eee 9. Fletcher’s solid flame gauze- ane ghia 29S Ge te oir oe ig. Dadwpitite "2 oe OP a A eee. ee Th “lanproved blewpipe.)..:-6 6 8s Fe SP ek ee 12. Another form of blowpipe s!0i'/i “WoL 2 Pw, a eee is. Candle flame ~ 3...) ba ee Bn ee tue Bunsen famier. 6%. -. 4° ee) a cee aes 2 ok Gee ee 15. Blowpipe fiesie «0640 wd Ht a) A 2

Ti; Goldering lnmmiy <i. a es Ooh te een eee 90 17. Compound. blowpips.. “2+ 4 ti! “1 Ss er gee ee 18. Spirit lamp . .. oT UAES gr) Sal rein PSone 19. Self-acting lamp ahi blowppige «dts he Oe ee ee 20; Apparatus for using gia |. BN Mae Te $i. Compitund blowpipe. 4... < f 5 ee ae oe 22. Foot-bellows . . sey ae Se Oe oa oe 23. Asbestos soldering- plock Fee ee line” PE teks care 24. Carbon soldering-block with a testets hands BORE igh OM 25. Cireular asbestos soldering-block or tray, mounted on wooden hanillg.: , oss...) s° pas 3A OD ee 26. A small hand furnace or soldering-pan. . .... . 99

27. Ingot molds for noble metals... oo 7 LOG 28. Apparatus suitable as a support for eedetng und: as an INGot- Mold. 2 Gb). *-5 E é-f LOO

29, An arrangement for Suliahe nae wound sh icials without -&- fargget 4.5 4 8 oh ee ee ee ee

30. Grénwall type of electric are furnace . . ... . . Ol

Sh. ceria. Damned Te) PAT ON a en dl a

FIG.

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41. 42.

43. 44,

60. 61.

ILLUSTRATIONS

Rheostat resistance coils; correct and defective wiring

Rheostat unassembled

Rheostat; under surface of iadinn don

Muffle cores ,

Several type of Lidell

Standard type of muffle Py er

Complete furnace without the ilies in ee

A furnace for purifying zine

Interior of bag house where oxides of eitale are “detention for commercial use

Specimens of native copper from ‘Like Sgeeior Kiateles

A vertical section of a copper mine in the Lake Superior district ‘

Calumet and Hecla mine

A crude type of blast furnace used ie satis Filipinos for the reduction of iron

Sectional view of blast furnace

A primitive Philippine Arastra

A eupel :

The ‘‘tail race’’ at Sutter’s Mill, California

A California prospector in early days

Ancient gold mining in the Sudan

Panning gold

The ‘‘cradle’’ in use in tie Ainities ald fields

Sluicing gold in Alaska

55-56. Two views of hydraulic juibations

A, primitive Philippine ee. hae by and’ « on the interior rivers .

A huge dredger operating in one of tha rivers in the Alaskan fields . RO sy oa ge

Doctor G. V. Black’s amalgam micrometer

Wedelstedt test tube ;

Form assumed by contracted sable, id

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118 168

Chapter I Introduction

CHEMISTRY is that branch of science which treats of the atomic conditions of matter, and especially of atomic changes. It comprehends the combination of diverse forms of matter producing new compounds, and the separating of already existing compounds into simpler ones, or resolving them into their ultimate principles, which are called—

ELEMENTS.—Substances whose molecules contain one kind of atoms only, and which all physical or chemical processes have as yet failed to break up or decompose into two or more dissimilar substances. It is not asserted that these substances are absolutely simple or elementary, or that they may not be found hereafter to yield more than one kind of matter, but merely so far as our knowledge extends it is so.

Kighty-three elements are at present known to us, of which the following is a partial list, arranged according to their electro-positive and -negative quality, or the electrochemical series. The most important are distinguished in the table by capitals, while those which at present are of slight importance, on account of their rare occurrence, or of our insufficient knowledge of their properties, are given in italies.

Atomic

Symbol — Valence Weightt Name

O Oe IGEN, od Sc So taig eral ye ale 1D iene terion 16.00 rs) CED, 250 va Beare ead bee Diag Ae) eee 32.06 N Dey oie edle'y oa Ha tk wee Pate, Rakes is 3 14.01 F AP UICVEOLINGEC- 45.6105 5 os Payee 1 Ae tarot eke Ee 19.00 Cl CE PALO, 5-4 wth.5:> etna arash TL, TEL, -V, Vikes<4 <35.46 Br EDR NAML ING" or AlS wis sptatotaia ot I, aul, ¥, Vil... 5) 97002 POTN aii ite fee ceisads tT, V,, VIE...) 18692 Se Sra era Eas Mrs lake ite ats etaes s yat a 1 ag 2a Re 79.2 Nes lied SCO) S N21 5G J: OU = Re er TUCO Per tesuaarayes 31.04 As "PATO Es Side ices oe BER SOW sn odes oe 74.96 Cr S CECE NMIT AT ote. Beatie aco oie Et, COr,)¥t,, UI. «ct. BBO Vv MVR CMEEMLULURY, | 5s, Sun aro 'a.d ote Bre 370s NUE) AV. Said os: Sacks es 51.0 Mo> "| Moljtdenimn <5 onc ec dcak is. 1 1 a Pa is 96.0 W *“\Tungsten (Wolfram)........ By BU VE Sette 184.0 B [SEO]. 2 peal ap eae eer 1 i are Acie 11.0 C AME 5 eves Waceuui TENE Srcner's Kile ota. Aner 12.0 Sb */|ANTIMONY (Stibium)..... | ae te a Be 120.2 Te TOUUPIOM Sona s do issaccese BE Ee Vike oe peat 127.5 BA EMO ik. ho CTS oes MUR, Mei 503 owt re 181.5 Cb = *|Columbiwm (Niobium)...... TIT, V.wweevanees 93.1 Ti PLE MOMPUROR: Fi pW cin dine wtb h ates a's TL areeor rs Cres 48.1 Si MOPED lates Ns dude hes « sae EV wiceseccews oes 28.3 ge § PEP DROGEN ous eis vcw ees. L $5 Unda oes 1.008 Ao STGOLD ‘(Aurum).... 5.5... T, IIl..........-. 197.2 BU Reg OE ee II, IV, VI, VIII. .| 190.9 Tr TM wii est igcdke Lec UI, EY .jcccpeaome 193.1 i Lg 2s) | a Tl, IV........... 195.2 Sar OUI id ace shakes. EY, SUV sv. coats oe 102.9 ee ee ee ee Ti, LV, Vij, Var. 361.7 Pd 1 OU el oF: i ee aie eae EE IV hoe eeiets 106.7 Hg *|MERCURY (Hydrargyrum). IL, (Eig, 25. 27 5% < 200.6 Ag *|Silver (Argentum).......... tL i soya easdeeowhetnts teleeannie 107.88 Cu *|COPPER (CUPRUM)......... TL, - {UR ies & aes 63.57

TABLE OF ELEMENTS

NEGATIVE END

Introduction

TABLE OF ELEMENTS—CONT ’D

NEGATIVE END

Symbol | __—_—— Valence Name

U i Oe he eee ee EY; TVs Wot Bi TES ERSNGAU ACH)” tagthnte state seve, Snes TER ss. ct ase Sn >| eae 4 GS Gam aia) tay are oe teste DE Dysart In STAIR ain Ponta) deca od oe {| BL Pane rs See ine ere ED “Laat” (Pinata) ys vn ohne Es" Sage Cd MACRO RUPMccges le eyarsus tate = see EE td. 6G ae Tl * | Dial 3: cs, ae as ea Se (Ppt Peer ss. Co *APEEILLLD yp 4 9) sonra OS Bae TE: LOo ios sters oe Ni TGs. ihe cM Pek ne Pete IT, (RVs. Fe RON: Thepruit) ons eh eartese LE, Va are vi sare Zn of 3s | CRA ee tee an ee TED 2c: thenapa: Srotieukeana Ga SSMU, is, seve Oh eo ae ete (Qe Ce Nae Saree ec Mn *|MANGANESIUM .......... IE, LV; Vi; VELL. La ©) LANTRIW UN: <5 4 4-5a-e Ne Oaieteks [EPS Ne GCA etree ote Ce bad Oe ee AME | ele! 2 LV; (CO)Vt,. sae ae Th SPONGE. i pieces cam eek Beebe Vine sre erate Sheers Tr tIZAPCOnGUHy «i lnk sats 9 te nae TTY Ss aah arabe ok hada Al AR LDV ONL nes chores age ky hee CRONE one ais ve Er PDS GS Fe DA se ae ree PERE git a ie oe a WHY Gepebilbe Joti sas 8 ttn tun tee series ELD: . eevee Gl *lGlucinum (Beryllium)....... eS ica, a ae Me *IMAGHRSLUM 35 ws seis cend MA Peeters Ca fr Rs ck SRP e remy certs 1) Rea ON See Sr FST RON TEUIND : .:. s'sstere cute woo IN EW teats cio Becta Ba gf oO RR, a eae ke Ae TEN ©, avevertersstued Li SELLE y Gost agele a hearty seers AL egies afips. ceeas aes Na *|SODIUM (Natriunt)....:... DB. 5% dae eee ate K *|POTASSIUM (Kalium)..... as sce ene cer chetts Rb ¥| UDIGHIIN: i540 6 bos pec eaee ae see aie ee eee Cs bi ig a OE ere ore oe Deeps ene dee Geel

Atomic Weight}

54.93 139.0

POSITIVE END

+Jour. Am. Chem. Soc., xxxviii, p. 2220.

These eighty-three elements are classed under two great divisions; viz., metallic and nonmetallic.

METALLIC ELEMENTS, the metals, or as they are frequently termed, the positive elements (denoted in the table by the*), usually having the ending ‘‘um’’ or “‘ium,’’ which signifies possessing metallic properties, are about sixty-two in number, and the study of these constitutes—

METALLURGY.—The science of economically extracting metals from their ores, and applying them to useful purposes.

AN ORE is a mineral cabot one or more metals in a free or combined state. The chief ores from which metals are obtained are sulphides, oxides, or carbonates. In some instances metals are obtained in paying quantities from such ores as chlorides, arsenides, sulphates, phosphates, or silicates. Gold and platinum are usually found in a free metallic state, then they are termed ‘‘native.’’ Tin, silver, copper, and some other metals are occasionally found native.

GANGUE.—The foreign material or impurity in which minerals are found embedded is variously known as ‘‘gangue,’’ ‘‘veinstone,’’ or ‘‘matrix.’’’ This may consist of such carbonates as ecale-spar, limestone; such silicates as feldspar, hornblende, and mica; such sulphates as heavy-spar; and such fluorides as fluor-spar. This is separated from the mineral by the miner in crushing, sorting, and washing operations known as ‘‘dressing,’’ after which the ore is sent to the metallurgist. Practically all this is now done at one plant known as the furnace or mill.

SLAG is the fused metallic dross separated from the metal bearing compounds when the minerals of

INTRODUCTION 21 iron, copper, silver, nickel, and cobalt are fused with arsenic, sulphur, or silica. Oxides unite with the silica and form a part of the slag.

REGULUS.—When the minerals of iron, copper and silver are smelted or fused with substances containing sulphur, the resulting sulphide is known as ‘‘regulus’’ or ‘‘matte.”’

SPEISS.—When the minerals of nickel and cobalt are similarly fused and converted into arsenides, the combination is termed ‘‘speiss.’’

REDUCTION is the process of freeing a metal from its combinations. There are three methods employed, viz.: fusion, leaching, and gaseous. Any substance employed in effecting this result is called a ‘‘reducing agent.’’? The chief reducing agents are carbon, hydrocarbons, carbon monoxide, and hydrogen. In this process metallic compounds are usually converted into oxides, if they do not already exist as such, which is generally accomplished by heating them in contact with atmospheric air. For example, when zine earbonate is thus treated, the reaction or reduction is as follows:

ZnCO, (+ heat) == ZnO + CO,

Then by addition of the reagent carbon the metallic zine is obtained thus:

2Zn0 + C = 2Zn + CO,

Sulphides are reduced by partially converting the metallic sulphide into an oxide, with the aid of heat, when the remaining metallic sulphide reacts with the oxide produced, freeing the metal, as for example:

PbS + 2PbO = SO, + 3Pb

These various processes are called ‘‘smelting.’’

ROASTING: When metalliferous substances are reduced to oxides by heating, in contact with atmospheric air, the process is called ‘‘roasting.’’ When they are similarly heated in contact with chlorine gas or with common salt, the operation is known as ‘‘chlorinizing roasting.’’

CALCINATION is the process of heating a substance at a temperature below its melting point. The object is to expel all volatile and organie matter, and, in the case of an ore, to render it more porous preparatory to roasting or smelting.

DISTILLATION.—The act of separating in the form of vapor the more volatile portions of a substance by heat, and subsequently condensing them to a liquid state in some cooling receiver or worm. Mercury and zine are extracted from their ores by this process, and the former metal is purified by redistillation.

SUBLIMATION is an analogous process, except that the substance separated as a vapor is condensed as a solid. For example, arsenic is sublimed from ores containing it.

SCORIFICATION is the process of converting the foreign substance present in a metallic compound into slag by oxidation and union with silica. The vessel in which the operation is effected is termed a ‘‘scorifier.’’

OCCLUSION is the property possessed by some metals of absorbing and retaining certain gases, thus—iron absorbs carbonic oxide readily, silver occludes oxygen, platinum will absorb considerable quantities of oxygen and hydrogen, and it has been demonstrated that palladium foil under certain circumstances will absorb 982 volumes of hydrogen.

INTRODUCTION 23

CEMENTATION is the reaction which takes place under heat between two substances without fusion.— Thus, when iron is heated with charcoal (carbon) a reaction takes place and the iron is said to become earburized. Such a reaction is known as ‘‘carburizing cementation.’’ When iron is heated with red hematite, Fe, O,, as an oxidizing agent, the impurities contained in it are modified or removed by the cement powder. Such a process is known as an ‘‘oxidizing cementation.’’

DRY PROCESS.—The operation of separating metals from metallic combinations or metalliferous matter by the agency of heat.

WET PROCESS.—The operation of separating metals from metallic combinations or metalliferous matter by suitable solvents, such as the ordinary acids, ete., and then precipitating those metals desired with proper reagents or by an electrochemical process.

Of the sixty-two elementary metals mentioned, only fourteen are ordinarily employed in their true metallic condition. These are:

Tron Aluminum Gold Copper Nickel Silver Lead Antimony Mercury Zine Magnesium Platinum Tin Bismuth

About twelve are more or less useful in the preparation of medicines, in the arts for coloring pigments, and for alloying purposes. These are:

Potassium Barium Cobalt Sodium Manganesium Cadmium Calcium Arsenicum Titanium

Lithium Chromium Uranium

The remaining thirty-six are more or less rare, and many of them are of little or no practical value in the metallic state. However, the steel industry has been revolutionized by the use of some of these rare metals, such as vanadium, molybdenum, and tantalum in making alloys, and the use of tungsten in incandescent lamps and radium in medicine is indicative of the benefits which may be derived from further researches in metallurgie procedure.

The metallurgist groups the metals into two classes, which are known as noble and base:

NOBLE METALS are those whose compounds with oxygen are decomposable by heat alone, at a temperature not exceeding redness. These are:

Mercury Rhodium Silver Ruthenium Gold Osmium Platinum Tridium Palladium

BASE METALS are those whose compounds with oxygen are not decomposable by heat alone, retaining oxygen at high temperatures.

The base metals are further subdivided with reference to their affinity for oyxgen and other chemical properties.

THE First Division contains five metals. They are very readily oxidized, and their oxides are all soluble in water, giving it a strongly alkaline reaction; so also are their phosphates and carbonates, with the exception of lithium phosphate, which is quite insoluble, and the carbonate, which is only sparingly soluble. They all energetically decompose water at ordinary tempera-

INTRODUCTION 25 tures, liberating hydrogen, and forming hydroxides in solution. They are soft, of low specific gravity, and fusible at low temperatures. These are:

Potassium Rubidium Sodium Cesium Lithium

THE Seconp Division contains six metals, all of which decompose water at ordinary temperatures with the exception of magnesium, combining with the oxygen. Their oxides of the common metals are more or less soluble in water, rendering it alkaline; but their neutral carbonates and phosphates are insoluble. These are:

Barium Calcium Strontium Magnesium Gluctmm (Berylliwm) Radiwm

Tue TxHirp Division contains twelve metals, of which but three are of much importance. Those which have been isolated do not decompose water at ordinary temperatures without the addition of a weak acid or a slight rise of temperature. Their oxides and carbonates are insoluble in water. These are:

Tue FourtH Division contains nine metals, the chief of which decompose water at a red heat. These are:

Tron Uranium Nickel Vanadium Cobalt Thallium Manganesium Indium Zine

THe Firra Division contains four metals, which do not decompose water at any temperature. These are:

Cadmium Bismuth Lead Copper

THe Srxra Division contains six metals. All the higher oxides of these metals have acid properties. These are:

Tin Molybdenum Antimony Tungsten Arsenic Tellurium

The nonmetallic elements may be divided according to their physical states at ordinary temperatures, thus:

Gases Oxygen Nitrogen Fluorine Hydrogen Chlorine Liquid Bromine Solids Carbon Sulphur Phosphorus

Boron Selenium Iodine Silicon

Chapter II

A METAL is an elementary substance, solid at ordinary temperatures, with the single exception of mercury (a liquid solidifying at—39° C.), having a peculiar luster, called metallic ‘‘luster,’’ insoluble in water, a conductor of heat and electricity, possessing the quality of uniting with oxygen to form a basic oxide, and having the property of replacing hydrogen in chemical reactions, as, for example:

No line can be sharply drawn between metals and nonmetals; just as no line can be drawn between soluble and insoluble, poisonous and nonpoisonous, substanees. The two elements, arsenicum and tellurium may well be considered the intermediate links between the two classes.

All metals, when exposed in an inert atmosphere to a sufficient temperature, assume the form of liquids and present the following characteristic properties: They are practically nontransparent and reflect light in a peculiar manner, producing what is called metallic luster. When melted in nonmetallic vessels, they take the shape of a convex meniscus. When exposed to greater temperatures, some sooner, others later, pass into vapors. What these vapors are like is not known in many eases, since, as a rule, they can be produced only at very high temperatures precluding the use of transparent vessels. Silver vapor is blue, that of potassium green, and many others—mercury, for example— colorless. The liquid metals, when cooled down sufficiently, some at lower, others at higher temperatures, congeal into compact solids, endowed with relative nontransparenecy and the luster of their liquids.

NONTRANSPARENCY.— Metals as a rule are nontransparent, or opaque, yet some have proved to possess the property of transparency in a low degree at least. In the ease of gold, through the leaf, or thin films produced chemically on glass plate, a light green color is transmitted. This is ascribed to the gold aggregating and allowing white light to pass through the interstices. Also very thin films of mereury are said to transmit light with a violet-blue color, and copper, it is claimed, is somewhat translucent; while silver in thin films .000083 of an inch thick is opaque in an atmosphere of hydrogen or coal-gas, but in the air transparenecy begins at 240° C. and is quite complete at 390° C.

COLOR.—Most metals range from the pure white of silver and tin to the bluish hue of lead. Bismuth is a light gray, with a delicate tinge of red. Copper is ealled the ‘‘red metal.’’ Gold is a rich yellow; barium and strontium a straw color, while calcium exhibits a little deeper shade of that color.

LUSTER.—Polished metallic surfaces, like those of other solids, divide any incident ray into two parts, of which one is refracted, while the other is reflected, with this difference, however, that the former is completely absorbed, while the latter, in regard to polarization, is quite differently affected, which fact, in all probability, accounts for the peculiar property of metallie luster.

ODOR AND TASTE.—Most metals are destitute of odor and taste. Peculiar odors are, however, evolved from some of them when heated; in fact, one of the means of determining arsenicum consists in the recognition of its characteristic smell of garlic when heated. Iron, copper, or zine when heated also evolve peculiar odors. The taste which is perceived in some is no doubt due to their peculiar character, although in some eases it may depend upon voltaie action set up by the chemical agency of the saliva, the metal not being perfectly pure. If a piece of zine be placed upon the tongue, and a piece of silver under it, and the edges joined, a metallic taste will be perceived dependent upon slow solution of the zine under galvanic action. The odor, Dr. Essig says, ‘‘may be noticed in a marked degree when holding in the hand a mass of an alloy composed of gold, platinum, tin, and silver prepared for use as amalgam.’’ The moisture of the hand, aided by its heightened temperature, seems to promote the galvanie action.