LIBRARY
OF THE
UNIVERSITY OF CALIFORNIA, Class
INTRODUCTION
TO THE
RARER ELEMENTS.
PHILIP E. BROWNING, PH.D.,
Assistant Professor of Chemistry^ Kent Chemical Laboratory, Yale University.
FIRST EDITION. FIRST THOUSAND
TJT.
/TV
Or
NEW YORK:
JOHN WILEY & SONS.
LONDON : CHAPMAN & HALL, LIMITED.
1903.
•WH1N39
Copyright, 1903,
BY PHILIP E. BROWNING.
ROBERT DRUMMOND, PRINTER, NEW YORK.
A\
PREFACE.
THIS small volume, prepared from material used by the author in a short lecture course given at Yale University, is intended to serve as a convenient handbook in the intro- ductory study of the rarer elements ; that is, of those elements which are not always taken up in a general course in chemistry. No attempt has been made to treat any part of the subject exhaustively, but enough references have been given to furnish a point of departure for the student who wishes to investigate for himself. Experimental work has been included except in the case of those elements which are unavailable, either because of their scarcity or because of the difficulty of isolating them.
The author has drawn freely upon chemical journals and standard general works. In his treatment of the rare earths he has made especial use of Herzfeld and Korn's Chemie der seltenen Erden and Truchot's Les Terres Rares,. works which he gladly recommends. He gratefully acknowledges the valuable assistance of his wife in preparing this ma- terial for the press.
NEW HAVEN CONN., April, 1903.
iii
115402
JOURNALS CITED.
American Chemical Journal.
American Journal of Science.
Analyst, The.
Annalen der Chemie und Phar- macie.
Annales de Chimie.
Annales de Chimie et de Phy- sique.
Annalen der Physik und Chemie.
Atti del la R. Accademia dei Lincei, Roma.
Berichte der Deutschen che- mischen Gesellschaft.
Bulletin de 1'Academie imperiale de St. Petersbourg.
Bulletin de la Socie"te chimique de Paris.
Bulletin of the U. S. Geological Survey.
Chemisches Central-Blatt.
Chemische Industrie.
Chemical News.
Chemiker-Zeitung.
Comptes rendus de 1' Academic des sciences (Paris).
Crell 's Annalen.
Engineering and Mining Journal.
Jahresbericht der Chemie.
Journal of the American Chemi- cal Society.
Journal of the London Chemical Society.
Journal of Physical Chemistry.
Journal fiir praktische Chemie.
Journal of the Russian Physical- Chemical Society.
Journal of the Society of Chemi- cal Industry.
Klaproth's Beitrage.
Kongl. Vetenskaps Academiens Handlingar (Stockholm).
Liebig's Annalen der Chemie.
Monatshefte fiif Chemie.
Nicholson 's Journal.
Philosophical Magazine.
Philosophical Transactions of the Royal Society.
Poggendorff 's Annalen.
Proceedings of the American Academy of Arts and Sciences.
Proceedings of the Royal So- ciety (London).
Rendiconto dell' Accademia delle Scienze Fisiche e Matematiche, Napoli.
Science.
Sitzungsberichte der kaiserlichen Akademie der Wissenschaften. Mathematisch - Naturwissen- schaftliche Classe (Wien).
Zeitschrift fiir analytische Chemie.
Zeitschrift fiir angewandte Chemie.
Zeitschrift fiir anorganische Chemie.
INDEXES TO THE LITERATURE OF CERTAIN ELEMENTS.
Caesium, Rubidium, and Lithium, Index to the Literature of; Fraprie. In preparation.
Cerium, Index to the Literature of (1751-1894); Magee. Smith- sonian Misc. Coll. (1895), No. 971.
Columbium, Index to the Literature of (1801-1887); Traphagen. Smithsonian Misc. Coll. (1888), No. 663.
Didymium, Index to the Literature of (1842-1893); Langmuir. Smithsonian Misc. Coll. (1894), No. 972.
Gallium, Index to the Literature of (1876-1903) ; } Browning.
Germanium, Index to the Literature of (1886-1903); > In prepara-
Indium, Index to the Literature of (1863-1903); ) tion.
Lanthanum, Index to the Literature of (1839-1894); Magee. Smithsonian Misc. Coll. (1895), No. 971.
Lithium, vid. Caesium.
Niobium or Columbium, vid. Columbium.
Platinum Metals, Bibliography of (1748-1897); Howe. Smith- sonian Misc. Coll. (1897), No. 1084.
Rubidium, vid. Caesium.
Selenium and Tellurium, Index to the Literature of; G. A. Smith. In preparation.
Tellurium, vid. Selenium.
Thallium, Index to the Literature of (1861-1896); Doan. Smith- sonian Misc. Coll. (1899), No. 1171.
Thorium, Index to the Literature of; Joiiet. Smithsonian Misc. Coll. In press.
Titanium, Index to the Literature of (1783-1876); Hallock. An- nals of the N. Y. Academy of Sciences (1876), I, 53.
Uranium, Index to the Literature of (1789-1885); Bolton. Smith- sonian Report for 1885, Part I, 915.
vii •
viii INDEXES TO THE LITERATURE OF CERTAIN ELEMENTS.
Vanadium, Index to the Literature of (1801-1877); Rockwell.
Annals of the N. Y. Academy of Sciences (1879), J» I33- Yttrium Group, Index to the Literature of the Rare Earths of;
Dales. In preparation. Zirconium, Index to the Literature of (1789-1898); Langmuir
and Baskerville. Smithsonian Misc. Coll. (1899), No. 1173.
Attention is called also to the following monographs:
Die Chemie des Thoriums; Koppel. Sammlung chemischer Vor- trage, Band VI. Pub. by Ferd. Enke, Stuttgart, 1901.
Studien iiber das Tellur; Gutbier. Pub. by C. L. Hirschfeld, Leip- zig, 1902.
La Chimie de L 'Uranium (1872—1902); Oechsner de Coninck. Pub. by Masson et Cie., Paris, 1902.
Die analytischer Chemie des Vanadins ; Valerian von Klecki. Pub. by Leopold Voss, Hamburg, 1894.
HE RARER ELEMENTS,
CAESIUM, Cs, 133.
Discovery. Caesium was discovered in 1860 by Bun- sen and Kirchhoff while they were engaged in the spectro- scopic examination of a mother-liquor from the waters of Durkheim spring (Pogg. Annal. cxm, 337; Chem. News n, 281). After the removal of the strontium, calcium, and magnesium, by well-known methods, and of the lithium as far as possible by ammonium carbonate, the mother- liquor was tested, and gave, in addition to the potassium, sodium, and lithium lines, two beautiful blue lines never before observed, near the strontium blue lines. Bunsen gave the name Caesium to the newly discovered element, from the Latin caesius, the blue of the clear sky.
Occurrence. Caesium is found in combination as follows :
(i) In minerals: Pollucite, H2Cs4Al4(SiO3)9, contains 3i~37%*Cs2O.
Beryl, Be3Al2(SiO3)6, contains 0-3% Cs2O.
(2) In certain mineral waters, among which are Durk- heim ( i liter contains about '0.21 mg. RbCl and 0.17 mg. CsCl), Nauheim, Baden-Baden, Frankenhausen, Kreuz- nacher, Bourbonne les Bains, Monte Catino, Wheal Clifford.
Extraction. Of the methods in use for the extraction of caesium the following may serve as examples:
* In the tabulation of percentages the nearest whole numbers have generally been used in this book.
3 THE RARER ELEMENTS.
(1) From pollucite. The finely powdered mineral is decomposed on a water-bath with strong hydrochloric acid. To the acid solution antimony trichloride is added, which precipitates the double chloride of antimony and caesium (3CsCl-2SbCl3) (Wells, Amer. Chem. Jour, xxvi, 265). Or the acid solution may be treated with a solution of lead chloride containing free chlorine. This precipitates a double chloride of caesium and tetravalent lead (2CsCl • PbCl4) (Wells, Amer. Jour. Sci. [3] XLVI, 186).
(2) From pollucite or lepidolite. The mineral is heated with a mixture of calcium carbonate and calcium chloride, and the fused mass is cooled and extracted with water. The liquid is then evaporated to a small volume, and sul- phuric acid is added to precipitate the calcium as the sul- phate. After nitration, evaporation is continued until the greater part of the hydrochloric acid has been expelled. Sodium or ammonium carbonate is then added to complete the removal of the calcium salt. Upon the addition of chloroplatinic acid the caesium and rubidium are precipi- tated as the salts of that acid. By the action of hydrogen upon these salts the platinum is precipitated, while the caesium and rubidium chlorides are left in solution.
(3) From lepidolite. The mineral is decomposed by heating with a mixture of calcium fluoride and sulphuric acid (vid. Experiment i).
The Element. A. Preparation. Elementary caesium may be obtained (i) by heating caesium hydroxide with aluminum to redness in a nickel retort (Beketoff, Bull. Acad. Petersburg iv, 247) ; (2) by heating caesium hy- droxide with magnesium in a current of hydrogen (Erd- mann and Menke, Jour. Amer. Chem. Soc. xxi, 259, 420); (3) by heating caesium carbonate with magnesium in a current of hydrogen (Graefe and Eckardt, Zeitsch. anorg. Chem. xxn, 158).
B. Properties. Caesium, the most positive of the metals,
CAESIUM. 3
is silvery white and soft. It takes fire quickly in the air, burning to the oxide. It melts at 26° C. Like the other alkaline metals it decomposes water. Determinations of its specific gravity range from 1.88 to 2.4.
Compounds. A. Typical forms. The following are typical compounds of caesium: Oxide, Cs2O. Hydroxide, CsOH. Carbonates, Cs2CO3; CsHCO3. Chloride, CsCl. Double chlorides, AgCl-CsCl; AgCl-2CsCl; HgCl2-CsCl;
HgCl2-2CsCl; HgCl2.3CsCl; 2HgCl2-CsCl; 5HgCl2-CsCl;
PbCl4-2CsCl; PbCl2.4CsCl; PbCl2-CsCl; 2PbCl2-CsCl;
2BiCl3-3CsCl; BiCl3-3CsCl; CuCl2-2CsCl; CuCl2-2CsCl +
2H2O; 2CuCl2-3CsCl + 2H2O; CuCl2-CsCl; Cu2Cl2-CsCl;
Cu2Cl2 - 3CsCl ; Cu2Cl2 - 6CsCl + 2H2O ; CdCl2 • 2CsCl ;
CdCl2-CsCl; 2AsCl3-3CsCl; 2SbCl3-3CsCl; SnCl2-CsCl;
Fe2Cl6-6CsCl; CoCl2-3CsCl; CoCl2-2CsCl; CoCl2-CsCl +
2H2O ; NiCl2 • 2CsCl ; NiCl2 • CsCl ; MnCl2 • 2CsCl ;
2MnCl2 • 2CsCl + sH2O ; MnCl2 • 2CsCl + 3H2O ; MnCl2 • CsCl
+ 2H2O; MnCl2-2CsCl + H2O; ZnCl2-3CsCl; ZnCl2-2CsCl;
MgCl2-CsCl-|-6H2O; AuCl3.CsCl; AuCl3-CsCl + o.sH2O;
PtCl4-2CsCl; PtCl2-2CsCl; PdCl2-2CsCl; TeCl4-2CsCl;
T1C13 • 3CsCl + H2O ; T1C13 - 2CsCl ; T1C13 • 2CsCl + H2O ;
2TlCl3-3CsCl.
Bromides, CsBr; CsBr3; CsBr5. Double bromides, HgBr2 - CsBr ; HgBr2 - 2CsBr ; HgBr2 - 3CsBr ;
2HgBr2-CsBr; PbBr2-4CsBr; PbBr2-CsBr; 2?bBr2-CsBr;
CuBr2-2CsBr; CuBr2-CsBr; CdBr2-3CsBr; CdBr2-2CsBr;
CdBr2 - CsBr ; 2 AsBr3 • 3CsBr ; CoBr2 • 3CsBr ; CoBr2 • 2CsBr ;
NiBr2 - CsBr ; ZnBr, - 3CsBr ; ZnBr2 • 2CsBr ; MgBr2 - CsBr +
6H2O; AuBr3-CsBr; TeBr4-2CsBr; 2TlBr3 • 3CsBr ;
TlBr3-CsBr.
Iodides, Csl; CsI8; CsI5. Double iodides, HgI2-CsI; HgI2.2CsI; HgIa.3CsI;
4 THE RARER ELEMENTS.
2HgI2.CsI;3HgI2.2CsI;PbI2.CsI;CdI2.3CsI;CdI2.2CsI;
CdI2-CsH-H2O; 2AsI3.3CsI; CoI2-2CsI; ZnI2-3CsI;
ZnI2-2CsI; TeI4-2CsI; TlI3-CsI. Mixed halides, HgCs3Cl3Br2; HgCs2Cl2Br2; HgCsClBr2;
Hg5CsClBr10; HgCs3Br3I2; HgCs2Br2I2; HgCsBrI2;
HgCs2Cl2I2; PbCs4(ClBr)6; PbCs(ClBr)3; Pb2Cs(ClBr)5. Double fluorides, 20sF - ZrF4 ; CsF - ZrF4 + H2O ; 2CsF • 3ZrF4 -f
2H20.
lodates, CsIO-3; 2CsIO3.I2O5; 2CsIO3-I2O5 + 2HIO3. Nitride, CsN3 (Jour. Amer. Chem. Soc. xx, 225). Nitrates, CsNO3; 3CsNO3-Cs(NO3)3 + H2O. Sulphates, Cs2SO4; CsHSO4; Cs2S2O7; Cs2O-8SO3. Alums, CsAl(SO4)2 + i2H2O; Cs2SO4-Mn2(SO4)3 + 24H2O;
Cs2S04.Ti203.3S03 + 24H20. Fluosilicate, Cs2SiF6. Chromates, Cs2CrO4; Cs2Cr2O7. Chloroplatinate, CsPtCl6.
B. Characteristics. With few exceptions the caesium compounds are soluble in water. They closely resemble the potassium and rubidium compounds, being for the most part isomorphous with them. A comparison of the solubilities of the alums and also of the chloroplatinates of the three elements, at a temperature of 15°-! 7° C.> follows :
100 parts of water will dissolve
CsAl(SO4)2 + i2H2O, 0.62 parts; Cs 2PtCl6, 0.18 parts. RbAl(SO4)2 + i2H2O, 2.3o " Rb2PtCl6, 0.20 " KA1(S04)2 +i2H20, 13.50 " K2PtCl6, 2.17 M Among the important insoluble salts are the chloroplati- nate (Cs2PtCl6), the alum (CsAl(SO4)2 + i2H2O), and the double chlorides with tetravalent lead (PbCl4-2CsCl), tetravalent tin (2CsCl-SnCl4?), and trivalent antimony (3CsCl-2SbCl3). The salts of caesium color the flame violet. The spectrum shows two sharply defined lines in the blue, designated on the scale as Csa and Cs/?.
RUBIDIUM. 5
Estimation, Separation, and Experimental Work. Vid. Ru- bidium.
RUBIDIUM, Rb, 85.4.
Discovery. Rubidium was discovered by Bunsen and Kirchhoff in 1861, by means of the spectroscope, in the course of some work upon a lepidolite from Saxony (J. B. (1861), 173; Chem. News in, 357). The alkaline salts had been separated by the usual methods and pre- cipitated with platinic chloride. The precipitate, when examined with the spectroscope, showed at first only the potassium lines. When it had been boiled repeatedly with water, however, the residue gave two violet lines situated between the strontium blue line and the potas- sium violet line at the extreme right of the spectrum. These increased in strength as the boiling continued, and with them appeared several other lines, among which were two almost coincident with the potassium red line (a) at the extreme left. These lines, observed for the first time, marked the discovery of an element ; because of their color Bunsen gave it the name Rubidium, from the Latin rubidus, the deepest red.
Occurrence. Rubidium, like caesium, is widely distrib- uted, but in very small quantities. It is found
(i) In minerals:
Lepidolite* R3Al(SiO3)3, contains 0.7-3.0% Rb2O.
Leucite, KAl(SiO3)2, " traces
Spodumene, ' LiAl(SiO3)2,
Triphylite, Li(Fe,Mn)PO4,
Lithiophilite, Li(Mn,Fe) PO4,
Carnallite, KMgCl3-6H2O,
Mica and orthoclase contain
* The more important mineral sources are indicated by italics.
6 THE RARER ELEMENTS.
(2) In certain mineral waters, among which are the following: Ungemach, Ems, Kissingen, Nauheim, Selters, Vichy, Wildbad, Kochbrunnen (Wiesbaden), Durkheim.
(3) In beet-root, many samples of tobacco, some coffee and tea, ash of oak and beech, crude cream of tartar, potashes, and mother-liquor from the Stassfurt potassium salt works.
Extraction. Rubidium may be extracted with caesium from lepidolite (vid. Extraction of Caesium).
The Element. A. Preparation. Elementary rubidium may be obtained (i) by heating the charred tartrates^to a white heat (Bunsen) ; (2) by reducing the hydroxide or the carbonate with magnesium (Winkler, Ber. Dtsch. diem. Ges. xxui, 51) ; (3) by reducing the hydroxide with alumi- num (Beketoff).
B. Properties. Rubidium is a soft white metal which melts at 38° C. It takes fire in the air, burning to the oxide. It decomposes water. Its specific gravity is 1.52.
Compounds. A. Typical forms. The following are typical compounds of rubidium: Oxide, Rb2O. Hydroxide, RbOH. Carbonates, Rb2CO3; RbHCO3. Chloride, RbCl. Double chlorides, HgCl2 • 2RbCl ; HgCl2 - 2RbCl + 2H2O ;
2HgCl2 - RbCl ; 4HgCl2 • RbCl ; PbCl4 • 2RbCl ; 2PbCl2 - RbCl ;
PbCl2 • 2RbCl + o. sH2O ; BiCl3 • 6RbCl ; BiCl3 • RbCl +
4H2O; CdCl2-2RbCl; 2AsCl3.3RbCl; 3SbCl8-5RbCl;
2SbCls - 3RbCl ; SbCl3 - RbCl ; 2SbCl3 - RbCl + H2O ;
MnCV 2RbCl + 2H2O ; ZnCl2 • 2RbCl ; MgCl2 • RbCl + 6H2O ;
AuCl3 • RbCl ; TeCl4 • 2RbCl ; T1C18 • 3RbCl + H2O ;
TlCl3-2RbCl + H2O. Chlorate, RbClO3. Perchlorate, RbClO4. Bromides, RbBr; RbBr3.
RUBIDIUM. 7
Double bromides, 2PbBr2-RbBr; PbBr2-2RbBr + o.5H2O;
2 AsBr3 • 3RbBr ; 2SbBr3 • 3RbBr ; AuBr3 - RbBr ;
TeBr4-2RbBr; TlBr3-3RbBr + H,O; TlBr3-RbBr + H2O. Iodides, Rbl ; RbI3. Double iodides, AgI-2RbI; PbI2-RbI + 2H2O; 2AsI3-3RbI;
2SbI3-3RbI; TeI4-2RbI; TlI3-RbI + 2H2O. lodates, RbIO3; RbIO3-HIO3; RbIO3-2HIO3. Nitride, RbN3.
Nitrates, RbNO3; 3RbNO3-Co(NO3)3 + H2O. Cyanide, RbCN.
Sulphates, Rb2SO4; RbHSO4; Rb2S2O7; Rb2Q.8SO3. Alums, RbAl(SO4)2 + i2H2O ; RbFe(SO4)2 + i2H2O ;
RbCr(SO4)2+i2H2O; Rb2SO4-Ti2O3-3SO3 + 24H2O. Chloroplatinate, Rb2PtCl6. Silicofluoride, Rb2SiF6.
B. Characteristics. The rubidium compounds are very similar to those of potassium and caesium (vid. Caesium). Among the important insoluble salts are the perchlorate (RbClO4), the silicofluoride (Rb2SiF6), the chloroplati- nate (Rb2PtCl6), the bitartrate (RbHD2C4H4O4), and the alums (RbAl(SO4)2 + i2H2O and RbFe(S04)2+ i2H2O). The salts of rubidium color the flame violet. The spec- trum gives two lines in the violet to the right of the caesium lines (Rba and Rb/?), also two lines not so distinct in the dark red (Rb?- and Rbd), near the potassium red line, at the left of the spectrum.
Estimation of Caesium and Rubidium. Caesium and ru- bidium may be estimated in general by the methods applied to potassium. They are usually weighed as the normal sulphates, after evaporation of suitable salts with sulphuric acid and ignition of the products ; other methods, however, such as the chloroplatinate and chloride methods, are possible. They may also be weighed with a fair degree of accuracy as the acid sulphates, after evaporation with an excess of sulphuric acid, and heating at 25o°-27o° C.
« THE RARER ELEMENTS.
until a constant weight is obtained (Browning, Amer. Jour. Sci. [4] xii, 301).
Separation of Caesium and Rubidium. These metals belong to the alkali group. From sodium and lithium they may be separated (i) by chloroplatinic acid, with which they form insoluble salts; and (2) by aluminum sulphate, with which they form difficultly soluble alums. From potassium they may be separated by the greater solubility of the potassium alum and chloroplatinate in water.*
Caesium and rubidium may be separated from each other (i) by the difference in solubility of the chloroplati- nates;* (2) by the difference in solubility of the alums;* (3) by the formation of the more stable and less soluble tartrate of rubidium; and (4) by the solubility of caesium carbonate in absolute alcohol. Probably the most satis- factory methods, however, are those suggested by Wells; they depend upon the insolubility of the following salts: caesium double chloride and iodide (CsCl2I) (Amer. Jour. Sci. [3] XLIII, 17), caesium-lead chloride (Cs2PbCl6) (ibid. [3] XLVI, 1 86), and caesium-antimony chloride (Cs2Sb2Cl9) (Amer. Chem. Jour, xxvi, 265).
EXPERIMENTAL WORK ON CAESIUM AND RUBIDIUM.
Experiment i. Extraction of ccesium and rubidium salts from lepidolite. Mix thoroughly in a lead or platinum dish 100 grm. of finely ground lepidolite with an equal amount of powdered fluorspar. Add 50 cm.3 of com- mon sulphuric acid and stir until the mass has the consistency of a thin paste. Set aside in a draught hood until the first evolution of fumes (SiF4 and HF) has nearly ceased. Heat on a plate or sand-bath at a temperature of 2Oo°-3oo° C. until the mass is dry and hard. Pulverize
* Vid. page 4.
EXPERIMENTAL WORK ON C/ESIUM AND RUBIDIUM. 9
and extract with hot water until the washings give no precipitate on the addition of ammonium hydroxide to a few drops. Evaporate the entire solution to about 100 cm.3 and filter while hot to remove the calcium sul- phate. Set the clear filtrate aside to crystallize. The crystals, consisting of a mixture of potassium, caesium, and rubidium alums, with some lithium salt, should be dissolved in about 100 cm.3 of distilled water, and allowed to recrystallize. This process of recrystallization should be repeated until the crystals give no test before the spec- troscope for either lithium or potassium. The amount of caesium and rubidium alums obtained will of course vary with the variety of lepidolite used. An average amount of the mixed alums of potassium, caesium, and rubidium from the first crystallization would be 10 grm. The pure caesium and rubidium alums finally obtained should be about 3 grm. (Robinson and Hutchins, Amer. Chem. Jour, vi, 74). Lithium may be extracted from the mother-liquor (vid. Experiment 12).
Experiment 2. Preparation of ccesium and rubidium sulphates (Cs2SO4; Rb2SO4). Dissolve in water a crystal of the caesium and rubidium alums obtained from lepido- lite, add a few drops of ammonium hydroxide, and boil. Filter off the aluminum hydroxide and evaporate the filtrate to dryness. Ignite until the ammonium sulphate is removed, dissolve in a few drops of water, filter, and evaporate to dryness. Sulphates of caesium and rubidium will remain.
Experiment 3. Preparation of the carbonates of ccssium and rubidium (Cs2CO3 ; Rb2CO3) . Dissolve in water a crystal of caesium and rubidium alums obtained from lepidolite, add an excess of barium carbonate, and boil. Filter off the alumina, barium sulphate, and excess of barium carbonate. Pass a little carbon dioxide through the clear filtrate and boil to remove traces of barium salt.
io THE RARER ELEMENTS.
Filter. Carbonates of caesium and rubidium will remain in solution.
Experiment 4. Formation of the double chloride of ccesium and tetravalent lead (2CsCl2-PbCl4). To a few cm.3 of a one per cent, solution of a caesium salt add a few drops of the reagent obtained by warming lead dioxide with hydrochloric acid and allowing the solution to stand until cool. Make a similar experiment, using a rubidium salt in place of the caesium salt. Note the absence of pre- cipitation in this case.
Experiment 5. Precipitation of the double chloride of caesium and antimony (3CsCl-2SbCl3). To a few cm.3 of a one per cent, solution of a caesium salt add some anti- mony trichloride in solution and evaporate to a small volume. The double chloride will be precipitated on cool- ing. Repeat the experiment, using a rubidium salt. Note the absence of precipitation in this case.
Experiment 6. Precipitation of the double salt ccesium chloride and stannic chloride (2CsCl-SnCl4). Make an ex- periment similar to Experiment 5, using stannic chloride in the place of antimonious chloride. Note the separa- tion of the double chloride on cooling. Make a similar experiment, using a rubidium salt.
Experiment 7. Precipitation of the chloroplatinates of ccesium and rubidium (Cs2PtCl6; Rb2PtCl6). To a few cm.3 of a solution of a caesium salt add a few drops of a solution of chloroplatinic acid. Make a similar experiment with a solution of a rubidium salt.
Experiment 8. Separation of ccesium from rubidium. Apply the information gained in the foregoing experi- ments to the separation of caesium from rubidium.
Experiment 9. Flame tests for ccesium and rubidium. Dip the end of a platinum wire into a solution of a caesium salt and test the action of the flame of a Bunsen burner upon it. Repeat, using a rubidium salt.
LITHIUM. 1 1
Experiment 10. Spectroscopic tests for ccesium and rubidium. Test solutions of caesium and rubidium salts before the spectroscope. Note the twin blue lines of the caesium spectrum and the twin violet lines of the rubidium.
Experiment n. Negative tests of ccesium and rubidium. Note that hydrogen sulphide, ammonium sulphide, and ammonium carbonate give no precipitates with salts of caesium and rubidium.
LITHIUM, Li, 7.03.
Discovery. In 1817 Arfvedson, working in Berzelius's laboratory upon a petalite from Uto, Sweden, discovered an alkali which he found to differ from those already known in the following particulars: (i) in the low fusing points of the chloride and sulphate; (2) in the hydroscopic char- acter of the chloride ; and (3) in the insolubility of the car- bonate. In his analysis of the mineral it had remained associated with sodium, not being precipitated by tartaric acid. To the newly discovered element the name Lithium was given, from Az'0o£, stone, because it differed from sodium and potassium in having a mineral rather than a vegetable origin (Ann. der Phys. u. Chem. (1818), xxix, 229 ; Ann. Chim. Phys. [2] x, 82). It has since been found, however, not only in the mineral kingdom, but in the vegetable and animal kingdoms also.
Occurrence. Lithium is found combined as follows:
(i) In minerals:
Petalite, LiAl(Si2O5)2, contains 2-5% Li2O.
Spodumene, LiAl(SiO3)2, " 4-8% "
Lepidolite, R3Al(SiOs)3, " 4-6% "
Zinnwaldite,(K,Li)3FeAl3Si5016(OH,F)2, " 3-4% «• Cryophyllite, complex silicates, vid. Zinnwaldite, contains. 4-5% Li.0.
12 THE RARER ELEMENTS.
Polylithionite, complex silicates, vid. Zinnwaldite, contains
about 9% Li2O.
Beryl, Be^^SiC^, contains 0-1% Li2O.
Triphylite, Li(Fe,Mn)PO4, " 8-9% " Litkiophilite, Li(Mn,Fe)P04, 8-9% "
Amblygonite, Li(AlF)PO4, " 8-10% "
Small amotints of lithium are found also in some varie- ties of tourmaline, in epidote, muscovite, orthoclase, and psilomelane.
(2) In certain mineral waters, among which are Durk- heim, Kissingen, Baden-Baden, Bilin, Assmannshausen, Tarasp, Kreuznach, Salzschlirf, Aachen, Selters, Wildbad, Ems, Homburg, Karlsbad, Marienbad, Egger-Franzen- bad, Wheal Clifford.
(3) In seaweed, tobacco, cacao, coffee, and sugar- cane ; in milk, human blood, and muscular tissue ; in me- teorites. It has been detected also in the atmosphere of the sun.
Extraction. Lithium may be extracted from minerals by the following methods:
(i) From triphylite or lithiophilite. The coarsely ground mineral is dissolved in Jiydrochloric acid to which nitric acid is gradually added, and the solution obtained is treated with a sufficient amount of ferric chloride to unite with all the phosphoric acid present. This solution is evaporated to dryness and the residue is extracted with hot water. The extract thus obtained is treated with barium sulphide, to remove the manganese and the last traces of iron. The barium is removed by sulphuric acid, and the filtrate is evaporated with oxalic acid and ignited. The alkalies remain as carbonates (Muller).
Lithium may be separated from the other alkalies by treajj^the mixed carbonates with water, lithium carbonate b^il^cQrnparatively insoluble. * (2) Prom lepidolite (or any other silicate). The mineral is
LITHIUM. 1 3
melted at red heat in a crucible, the melted mass is cooled rapidly in water and pulverized. Sufficient water is added to give the material the consistency of paste. Hydrochloric acid of specific gravity 1.2, equal in weight to the weight of the mineral taken, is gradually added, with stirring. The mass is allowed to stand for twenty-four hours. It is then heated again to about 100° C., with stirring, and a second portion of acid equal to the first is added. Upon several hours' heating the silica separates in the form of powder, and after treatment with nitric acid to oxidize the iron, the soluble material is separated by filtration from the silica. The filtrate is heated to the boiling-point and treated with sodium carbonate, which precipitates iron, aluminum, calcium, magnesium, manganese, etc. These are removed by filtration, and the liquid is evaporated to a small volume and filtered again if necessary. Lithium carbonate is precipitated by more sodium carbonate (Schrotter).
The Element. A. Preparation. Elementary lithium may be obtained by subjecting the fused chloride to elec- trolysis. Because of its volatility it cannot, like sodium and potassium, be prepared by heating the carbonate.
B. Properties. Lithium is a metallic element which has a silvery-white luster and which oxidizes in the air, though more slowly than potassium and sodium. It decomposes water at ordinary temperatures, and is light enough to float in petroleum. Its melting-point is 180° C. ; its specific gravity is 0.59.
Compounds. A. Typical forms. The following are typical compounds of lithium:
Oxide, Li2O.
Hydroxide, LiOH.
Carbonate, Li2COs.
Chloride, LiCl.
Chlorate, LiC108 + o.5H2O.
14 THE RARER ELEMENTS.
Perchlorate,
Bromide, LiBr.
Bromate, LiBrO3.
Iodide, LiI + sH2O.
lodate, LiIO3 + o.5H2O.
Periodate, LiIO4.
Fluorides, LiF; LiF-HF.
Nitride, LiN3.
Nitrite, LiNO2 + o.5H2O.
Nitrate, LiNO3.
Sulphide, Li2S.
Sulphite, Li2SO3.
Sulphates, Li2SO4; KLiSO4; NaLiS04; etc.
Phosphates, LiH2PO4; Li3PO4 + o.5H20; Li4P2O7.
Carbide, Li2C2.
Silicofluoride, Li2SiF6 + 2H2O.
B. Characteristics. Most of the salts of lithium are easily soluble in water; the principal exceptions are the carbonate and the phosphate, which are difficultly soluble. Lithium resembles sodium more closely than it resembles the other alkalies, in that it does not form an insoluble chloroplatinate, nor a series of alums. The nitrate and the chloride are soluble in alcohol. The compounds of lithium color the flame brilliant crimson.
Estimation. Lithium is usually weighed as the sul- phate or chloride.
Separation. Lithium may be separated from the other members of the alkali group (i) by the ready solubility of its chloride in amyl alcohol (Gooch, Amer. Chem. Jour, ix, 33) ; (2) by the solvent action of absolute ethyl alcohol upon the chloride; (3) by the insolubility of the phosphate; and (4) by the comparative insolubility of the carbonate.
EXPERIMENTAL WORK ON LITHIUM. 15
EXPERIMENTAL WORK ON LITHIUM.
Experiment 12. Extraction of lithium salts from tri- -phylite or lithiophilite. Dissolve 25 to 50 grm. of finely powdered mineral in common hydrochloric acid, add sufficient nitric acid to oxidize the iron, and enough ferric chloride to combine with all the phosphoric acid present. Evaporate to dryness and extract with hot water. Treat the extract with barium hydroxide in slight excess. Filter, add sulphuric acid to complete precipitation of barium sulphate, and filter again. Convert the sulphates present into carbonates by the careful addition of barium carbonate, filter, acidify the filtrate with hydrochloric acid, evaporate to dryness, and extract the lithium chloride with alcohol.
(Lithium salts may be extracted also from the mother- liquor after the extraction of caesium and rubidium salts from lepidolite. The liquor is treated with barium car- bonate in excess and is then boiled and filtered. The filtrate is acidified with hydrochloric acid, evaporated to dryness, and extracted with alcohol.)
Experiment 13. Precipitation of lithium phosphate (Li3PO4) . To a solution of a lithium salt add sodium phos- phate in solution.
Experiment 14. Precipitation of lithium carbonate (Li2CO3). To a few drops of a concentrated solution of a lithium salt add sodium carbonate in solution.
Experiment 15. Solvent action of alcohol upon lithium salts. Try the action of ethyl or amyl alcohol upon a little dry lithium nitrate or chloride.
Experiment 16. Flame and spectroscopic tests for lithium, (a) Dip a platinum wire into a solution of a lithium salt and hold in a Bunsen flame. Note the color.
(6) Observe the lithium flame by means of the spectro- scope. Note the bright crimson line between the potas- sium and sodium lines.
1 6 THE R/4RER ELEMENTS.
Experiment 17. Negative tests of lithium salts. Note that hydrogen sulphide, ammonium hydroxide, ammonium carbonate acting upon dilute solutions, and chloroplatinic acid give no precipitate with lithium salts.
BERYLLIUM OR GLUCINUM, Be or Gl, 9.1. Discovery. In the year 1797, Vauquelin discovered beryl- lium or glucinum in the mineral beryl (Ann. de Chim. xxvi, 155). After having removed the silica in the usual manner, he precipitated with carbonate of potassium, and treated the precipitate with a solution of caustic potash. The greater part of the precipitate dissolved, leaving a residue which he found to consist of a small amount of iron oxide and an oxide which dissolved in sulphuric acid. This solution gave, on evaporation, irregular crystals having a sweetish taste and forming no alum with potassium sulphate. The sweet taste suggested for the new element present the name Glu- cinum, from yhvKvt, sweet. Recently the name Beryllium, from the chief source, beryl, has come into more general use.
Occurrence. Beryllium occurs in minerals as follows :
Beryl, Be3Al2(SiO3)6, contains u-i5%BeO.
Chrysoberyl, BeAl2O4, 19-20% "
Bertrandite, Be2(Be-OH)2Si2O7, " 40-43% '•'
Phenacite, Be2SiO4, 44-46% "
Leucophanite, Na(BeF)Ca(SiO3)2, " 10-12% "
Meliphanite, NaCa2Be2FSi3O10 " 10-14% "
Epididymite, HNaBeSi3O8, " 10-11% "
Enclose, Be(Al-OH)SiO4, 17-18% "
Helvite or danalite, R5(R2S)(SiO4)3, " 13-14% "
Gadolinite, FeBe2Y2Si2O10, 5~n% "
Trimerite, Be(Mn,Ca,Fe)SiO4, " 16-17% "
Beryllionite, NaBePO4, *' 19-20% "
Herderite, Ca(Be(OH,F))PO4, " 15-16% "
Hambergite, Be(BeOH)BO3, " 53~54% 4<
BERYLLIUM OR GLUCINUM. 17
Extraction. Beryllium is generally extracted from beryl by one of the following methods :
(1) The mineral is fused with sodium and potassium carbonates (vid. Experiment 18).
(2) The finely ground mineral is fused with three times its weight of potassium fluoride. The fused mass is treated with strong sulphuric acid and warmed; by this process the silica is removed as silicon fluoride, and the alumina and potash are united to form the alum, which may be crystallized out on evaporation. The beryllium remains in solution as the sulphate, and may be removed by treat- ment with ammonium carbonate (vid. Experiments 18 and 20).
(3) The mineral is fused with calcium fluoride. This process is in general the same as the one indicated in the second method, except that calcium sulphate is formed and must be removed (Lebeau, Chem. News LXXIII, 3).
The Element. A. Preparation. Elementary beryllium may be obtained (i) by bringing together the vapor of the chloride and sodium in a current of hydrogen (De- bray, Ann. Chim. Phys. (1855) XLIV, 5); (2) by fusing the chloride with potassium (Wohler, Pogg. Annal. xiu, 577); (3) by heating the chloride in a closed iron crucible with sodium (Nilson and Pettersson, Ber. Dtsch. chem. Ges. xi, 381, 906); (4) by heating the oxide with magnesium (Winkler, Ber. Dtsch. chem. Ges. xxm, 120).
B. Properties. The element beryllium is grayish to white in color. Unchanged in the air at ordinary tem- peratures, it burns brightly to the oxide when heated in air or in oxygen. It does not decompose hot or cold water. Heated in sulphur vapor it forms the sulphide, and in chlorine the chloride. It is soluble in dilute and in con- centrated acids; also in potassium hydroxide with the liberation of hydrogen. Determinations of its specific gravity range from 1.64 to 2.1.
1 8 THE R4RER ELEMENTS.
Compounds. A. Typical forms. The following are typical compounds of beryllium: Oxide, BeO. Hydroxide, Be(OH)2.
Carbonates, BeCO3+4H2O; #BeCO3-;yBeO. Chlorides, BeCl2; BeCl2 + 4H2O; *BeCl2-;yBe(OH)2 + 0H2O. Chlorate, Be(ClO4)2 + 4H2O. Bromides, BeBr2; BeBr2 + 4H2O. Iodide, BeI2.
Fluorides, BeF2; BeF2-KF; BeF2-2KF. Nitrates, Be(NO3)2 + 3H2O; Be(NO3)2-Be(OH)2-f 2H2O;
Be(NO3)2-2BeO.
Sulphates, BeSO4; BeSO4 + 4H2O; BeSO4 + 7H2O. Sulphites, BeSO3; BeSO3-BeO; 3BeSO3-BeO. Phosphate, Be3(PO4)2 + 6H2O. Ferrocyanides, Be2FeC6N6; Be2Fe(CN)6-4Be(OH)2.
B. Characteristics. The compounds of beryllium closely resemble those of aluminum. The oxide is white, in- soluble in water, and when freshly precipitated soluble in excess of potassium hydroxide. If this solution is di- luted and boiled, the oxide is reprecipitated ; in this reaction beryllium differs from aluminum. The salts of beryllium with the stronger acids (hydrochloric, nitric, and sulphuric) are soluble, like the corresponding salts of aluminum. The sulphate of beryllium does not unite with potassium sul- phate to form an alum. Ammonium carbonate precipi- tates the basic carbonates of both aluminum and beryl- lium, but the beryllium carbonate is very soluble in excess and may be reprecipitated by boiling.
Estimation. Beryllium is ordinarily estimated as the oxide, (BeO), which is obtained by the ignition of the pre- cipitated hydroxide.
Separation. Beryllium falls into the aluminum group, and it closely resembles that element in many reactions. It may be separated from aluminum (i) by boiling a dilute
,
EXPERIMENTAL WORK ON BERYLLIUM. 19
solution of the two hydroxides in sodium or potassium hydroxide, beryllium hydroxide being precipitated; (2) by precipitating the basic acetate of aluminum, the beryl- lium salt remaining in solution; and (3) by saturating a solution of the two chlorides with hydrochloric acid gas in the presence of ether, the beryllium remaining in solu- tion, while the aluminum chloride is precipitated (Gooch and Havens, Amer. Jour. Sci. [4] n, 416).
EXPERIMENTAL WORK ON BERYLLIUM.
Experiment 18. Extraction of beryllium salts from beryl (Be^l^O^). Fuse in a clay crucible 10 grm. of finely powdered mineral with 20 grm. of a mixture of sodium and potassium carbonates, and cool. Pour about 20 cm.3 of common sj^huric_acid over the fused mass and stir 0»o until it becomes gelatinous. Heat until the excess of sul- phuric acid is driven off and extract with water. Evapo- rate to about 100 cm.3, filter if necessary, and allow the potash alum to crystallize out. After removing the alum, saturate the filtrate with ammonium carbonate in the cold, allow it to stand for several hours, and filter. Boil the filtrate and collect the basic beryllium carbonate precipi- tated (#BeCO3 • ;yBeO) . To purify this salt from iron, dis- solve it in a small amount of acid, add potassium hydroxide in excess, filter off the ferric hydroxide precipitated, dilute the filtrate, and boil.
Experiment 19. Precipitation of beryllium hydroxide (Be(OH)2). (a) To a solution of a beryllium salt add ammonium hydroxide, and note the insolubility of the precipitate in excess of that reagent.
(6) To another portion of the beryllium solution add a solution of potassium or sodium hydroxide, and note the solvent action of an excess.
(c) Dilute with water a portion of the alkaline solution
20 THE RARER ELEMENTS.
obtained in (b) and boil. Note the reprecipitation of the hydroxide.
(d) To another portion of the alkaline solution ob- tained in (6) add ammonium chloride, and boil.
(e) To a solution of a beryllium salt add ammonium sulphide.
Experiment 20. Precipitation of beryllium carbonate (#BeCO3-;yBeO). (a) To a solution of a beryllium salt add sodium or potassium carbonate in solution. Note the solvent action of an excess and the reprecipitation on boiling.
(b) Make a similar experiment, using ammonium car- bonate.
Experiment 21. Precipitation of beryllium phosphate (Be3(PO4)2). To a solution of a beryllium salt add a solu- tion of sodium phosphate.
Experiment 22. Precipitation of beryllium ferrocyanide (Be2Fe (CN) 6 • 466 (OH) 2) . To a solution of a beryllium salt add a little potassium ferrocyanide in solution.
Experiment 23. Negative tests of beryllium salts. Try the action of hydrogen sulphide and ammonium oxalate upon separate portions of a solution of a beryllium salt. Add sodium acetate to a solution of a beryllium salt and boil. Note the absence of precipitation in each case.
YTTRIUM, Y, 89.
Discovery. In the year 1794 Gadolin (Kongl. Vet. Acad. Handl. xv, 137; Crell Annal. (1796) i, 313) discov- ered a new earth * in a mineral from Ytterby later1 called Gadolinite, which had been discovered by Arrhenius and described by Geyer in 1788 (Crell Annal. (1788) i, 229).
* The term earth is applied to certain metallic oxides which were formerly regarded as elementary bodies, as Y2O3, Er2O3, La2Os, etc., and names ending in a are often used in designating them, as yttria, erbia, etc. The ending um designates the element, as yttrium, erbium, lanthanum.
YTTRIUM. 21
In 1797 Eckeberg confirmed Gadolin's discovery and named the new earth Yttria (Kong. Vet. Acad. Handl. xvm, 156; Crell Annal. (1799) n, 63).
Occurrence. Yttrium occurs always in combination. Yttrium earths, chiefly Y2O3, are found as shown in the following table:
Gadolinite, FeBe2Y2Si2O10 22-46%
in
Yttrialite, R2O3-2SiO2 46-47%
Cappelenite, complex silicates . . 52~53%
Melanocerite, " 9~io%
Caryocerite, " " 2-3%
Tritomite, " " 2-3%
ii in
Allanite or orthite, HRR3Si3O13 0-4%
Cenosite, H4Ca2(Y,Er)2CSi4O17 - 37~38%
Thalenite, H2Y4Si4O15 58-63%
Rowlandite, *Y2O3 -^SiO2 61-62%
Bodenite, vid. Allanite 17-18%
Muromonite, " " 37-38%
Keilhauite, complex silicates. 6-7%
Tscheffkinite, " 0-3%
Johnstrupite, ' ' i- 2%
Mosandrite, o- 3%
Rinkite, " " o- i%
Xenotime, YPO4 54-64%
Monazite, (Ce,La,Di)PO4 0-5%
Rhabdophanite, RPO4 -H2O 2-10%
in
Yttrocerite, 2(2RF3-9CaF2) -3H20 14-15%
Fluocerite, R2O3-4RF3 3-4%
ii in
Samarskite, R3R2(Nb,Ta)6O21 12-16%
in in
Euxenite, R(NbO3)3 -R2(TiO3)3 -|H2O ' . . . . 13-30%
in
Fergusonite, R(Nb,Ta)O4 30-46%
ii in
Yttrotantalite, RR2(Ta,Nb)4015-4H20 17-20%
22 THE RARER ELEMENTS.
Hatchettolite, R(Nb,Ta)2O6-H20 0-2%
o
Annerodite, complex niobate 7- 8%
Hielmite, complex stanno-tantalate J~ 5%
in in ^schynite, R2Nb4O13 .R2(Ti,Th)5O13 1-3%
Polymignite, SRTiO3 • SRZrO3 -R(Nb, Ta)2O6 2- 3%
III III
Polycrase, R(NbO3)3 • 2R(TiO3)3 • sH2O 20-32%
Arrhenite, complex tantalo-niobate 22-23%
Rogersite, " '" " 60-61%
Sipylite, complex niobate, Er2O3. . .27%; Y2O3. . . i%
Extraction. The following are common methods for the extraction of yttrium salts from minerals:
(1) From gadolinite (or any other silicate). The finely powdered mineral is mixed with common sulphuric acid until the mass has the consistency of thick paste. It is then heated until dry and hard, pulverized, and extracted with cold water. From this extraction the oxalates are precipi- tated by the addition of oxalic acid ; they are then washed, dried, and heated at 400° C. The oxides thus obtained are dissolved in sulphuric acid, and the solution is saturated with potassium or sodium sulphate. The double sulphates of the cerium group are precipitated, and the members of the yttrium group remain in solution.
(2) From gadolinite. The mineral is decomposed by aqua regia (vid. Experiment 24).
(3) From samarskite. The mineral is decomposed by hydrofluoric acid. The niobic and tantalic acids go into solution, and the yttrium earths, together with uranium oxide, remain (Lawrence Smith, Amer. Chem. Jour.
v, 44).
The Element. A. Preparation. Elementary yttrium may be obtained (i) by heating the chloride with potas- sium (Berzelius) ; (2) by subjecting the melted double
YTTRIUM. 23
chloride of sodium and yttrium to electrolysis (Cleve, Bull. Soc. Chim. d. Paris [2] xvm, 193) ; (3) by heating the oxide with magnesium (Winkler, Ber. Dtsch. chem. Ges. xxm, 787).
B. Properties. Yttrium is a grayish-black powder, which decomposes water only slightly at ordinary tempera- tures, but more rapidly on boiling, forming the oxide. Ignited on platinum in the air, it burns to the oxide with a brilliant light ; in oxygen with a very intense glow. It is very soluble in dilute acids, including acetic, but is only slightly soluble in concentrated sulphuric acid. It decom- poses potassium hydroxide at the boiling temperature.
Compounds. A. Typical forms. The following are typ- ical compounds of yttrium:
Oxide, Y2O3. Hydroxide, Y(OH)3.
Carbonates, Y2(CO3)3 + 3H2O ; Y2(CO3)3 - Na2CO3 + 4H2O ; Y2(C03)3-(NH4)2C03 + 2H20.
Chlorides, YC13; YC13 + 6H2O; YCl3.3HgCl2 + 9H2O;
YC13 • 2AuCl3 + i6H2O ; 2YC13- 3PtCl2+ 24H2O.
Chlorate, Y(C1O3)3 + 8H2O. Perchlorate, Y(C1O4)3 + 8H2O. Bromides, YBr3; YBr3 + gH2O. Bromate, Y(BrO3)3 + 9H2O. Iodide, YI3.
lodate, Y(I03)3 + 3H20. Periodate, Y2O3-I2O7 + 8H2O. Fluoride, YF3 + o.5H2O.
Nitrates, Y(N03)3 + 6H2O; 2Y2O3.3N2O5 + 9H2O. Cyanides, YKFe(CN)fl + 2H2O; Y(SCN)3 + 6H2O. Sulphates, Y2(S04)3 + 8H2O ; Y2(SO4)8 - 4K2S04 ;
Y2(S04)3.Na2C03 + 2H20. Sulphite, Y2(S08)3 + 3H20.
24 THE RARER ELEMENTS.
Seleniates, Y2(SeO4)3 + 8H2O ; Y2(SeO4)3 • K2SeO4 + 6H2O ;
Y2(Se04)3.(NH4)2Se04 + 6H20. Selenites, Y2(SeO3)3 + 1 2H2O ; Y2O3 • 4SeO2 + 4H2O. Sulphide, Y2S3. Oxalate, Y2(C2O4)3 + 9H2O. Phosphates, YPO4; Y(PO3)3; YHP2O7 + 3.5H2O. Chromate, Y2(CrO4)3 - K?CrO4 + #H2O. Tungstate, Y2(WO4)3 + 6H2O. Carbide, YC2.
B. Characteristics. The compounds of yttrium have few characteristic reactions. They resemble quite closely the compounds of aluminum, but yttrium differs from aluminum in having a hydroxide insoluble in excess of sodium or potassium hydroxide and in forming no alums. The salts of yttrium give no absorption spectra. Yttrium sulphate differs from the sulphate of cerium in forming no insoluble double sulphate with potassium or sodium sulphate.
Estimation. Yttrium is generally weighed as the oxide, (Y2O3), which has been obtained by the ignition of the hydroxide or the oxalate.
Separation. In the course of analysis the yttrium earths are precipitated with the aluminum group. They may be separated from aluminum by precipitation with oxalic acid or ammonium oxalate in faintly acid solution; in this reaction they resemble the other members of the rare-earth group (Ce, La, Di, Th, Zr, etc.). They may be separated from these by saturating a solution of the sul- phates with potassium sulphate; the yttrium earths do not form a double sulphate insoluble in potassium sulphate as do the others.
For the separation of yttrium from the very rare mem- bers of its group (Yb, Er, Tr, etc.), vid. Dennis and Dales, Jour. Amer. Chem. Soc. xxiv, 401.
EXPERIMENTAL WORK ON YTTRIUM. 2 5
*
EXPERIMENTAL WORK ON YTTRIUM.
Experiment 24. Extraction of yttrium salts from gado- linite (Be2FeY2Si2O10). Warm 5 grm. of finely powdered mineral with aqua regia until it is completely decomposed. Evaporate on a water-bath and desiccate to remove the silica. Extract with hot water and a little hydrochloric acid, and add to the extract ammonium oxalate until precipitation ceases. Filter off the precipitate, which con- sists of the oxalates of the yttrium and cerium groups, to- gether with traces of the oxalates of manganese and cal- cium; dry and ignite. Dissolve in a small amount of hydrochloric acid the oxides thus obtained, and saturate the solution with potassium sulphate; this precipitates the members of the cerium group as the double sulphates. Filter, and wash with a solution of potassium sulphate. From the filtrate precipitate the yttrium earths by an alkali hydroxide or oxalate. To remove the manganese and calcium, dissolve the precipitate in nitric acid, evapo- rate to dryness, and heat until the manganese salt is decom- posed. Extract with water, filter off the oxide of man- ganese, treat the filtrate with ammonium hydroxide, and stir thoroughly. The calcium hydroxide will be dissolved, and the yttrium earths precipitated.
Experiment 25. Precipitation of yttrium hydroxide (Y(OH)3). (a) To a solution of an yttrium salt add am- monium hydroxide.
(6) Repeat the experiment, using sodium or potassium hydroxide.
Note the insolubility in excess in each case.
(c) Precipitate yttrium hydroxide by the action of ammonium sulphide.
Experiment 26. Precipitation of yttrium carbonate (Y2(CO3)3). (a) To a solution of an yttrium salt add ammonium carbonate.
26 THE RARER ELEMENTS.
(b) Repeat the experiment, using sodium or potassium carbonate.
Note the solubility in the cold upon the addition of an excess of the alkali carbonates, and the reprecipitation on boiling.
(c) Try the action of the common acids upon yttrium carbonate.
Experiment 27. Precipitation of yttrium oxalate (Y2(C2O4)3). To a solution of an yttrium salt add a solu- tion of either oxalic acid or an alkali oxalate.
Experiment 28. Precipitation of yttrium phosphates (Y2(HPO4)3; YPO4). To a solution of an yttrium salt add sodium phosphate in solution (Na2HPO4). The pre- cipitate is said to be of the acid form Y2(HPO4)3. The neutral phosphate (YPO4) is formed by treating an yttrium salt in solution with an ammoniacal phosphate.
Experiment 29. Precipitation of yttrium ferrocyanide (YKFe(CN)6). To a solution of an yttrium salt add potas- sium ferrocyanide.
Experiment 30. Precipitation of yttrium chr ornate (#Y2(CrO4)3-;yY2O3). To a solution of an yttrium salt add a solution of potassium chromate, and neutralize if necessary.
Experiment 31. Precipitation of yttrium fluoride (YF3). To a solution of an yttrium salt add potassium fluoride.
Experiment 32. Negative tests of yttrium salts. Note that hydrogen sulphide gives no precipitate with yttrium salts, and that saturation of a solution of an yttrium salt with potassium or sodium sulphate gives no insoluble double salt.
THE GADOLINITE OR YTTRIUM EARTHS
OTHER THAN YTTRIA.
Associated with yttria, and resembling it in many reactions, are several very rare earths which, together with yttria, comprise the group called the Gadolinite or Yttrium
THE GADOLINITE OR YTTRIUM EARTHS. 27
Earths. The metals of these very rare oxides are the following:
!^> IL
Terbium, Tfc 161-3 Samarium, Sm, 150
Erbium, Er, 166 Decipium, Dp, 171
Holmium, Ho, 162 Gadolinium, Gd, 156
Thulium, Tm, 171
Dysprosium, Dy.
Ytterbium, Yb, 173
Philippium, Pp, 123-6
Scandium, Sc, 44 . i
The elements in column II are classed by some authori- ties with the cerium group.
Discovery.* In 1843 Mosander (J. pr. Chem. xxx, 288) announced, as the result of his investigation of yttria, its separation into three earths, two white and one yellow. To the less basic of the white oxides he gave the name Terbium earth, to the more basic the original name Yttrium earth, and the yellow oxide he called Erbium earth.
In 1878 Marignac (Compt. rend. LXXXVII, 578) found in gadolinite the oxide of a new element which he named Ytter- bium, and the same year Delafontaine (Compt. rend. LXXXVII, 559, 632) announced the isolation from a North Carolina samarskite of the earths of Decipium and Philippium.
The following year Nilson (Ber. Dtsch. chem. Ges. xn, 554), while engaged in extracting ytterbium from euxenite, separated an earth of much lower atomic weight, the unknown element of which he called Scandium. Another earth isolated in 1879 is the oxide of Samarium, discovered by Lecoq de Boisbaudran (Compt. rend. LXXXVIII, 323) in the course of an examination of the absorption spectra of the earths separated from samarskite.
In 1880 Cleve (Compt. rend. LXXXIX, 478), while work-
* For a recent and more detailed account of the discovery of these earths -vid. Baskerville, Science, New Series, xvn, 774.
28 THE RARER ELEMENTS.
ing on erbium earth, discovered two elements, Holmium and Thulium, which he separated as the oxides.
Six years later Marignac and Lecoq de Boisbaudran (Compt. rend, en, 902), during the study of terbium earth, separated the oxide of an unknown element named by them Gadolinium, and in the same year Lecoq de Bois- baudran (Compt. rend, en, 1004) made the further an- nouncement of the isolation of a new earth from the oxide of holmium, that of Dysprosium.
Occurrence. These earths are found associated with yttrium in small quantities and varying proportions (vid. Occurrence of Yttrium).
Extraction.* Methods for the extraction of the yttrium earths have already been given (vid. Extraction of Yttrium). Methods for their separation are as follows:
(1) Fractional precipitation by ammonium hydroxide (Mosander) ;
(2) Fractional precipitation by potassium oxalate (Delafontaine) ;
(3) Successive ignitions of the nitrates, and extractions with water (Bahr and Bunsen) ;
(4) Precipitation by means of lactic acid (Waage) ;
(5) Treatment with ethylsulphate (Urbain).
The Elements. The metallic elements of these earths have not been isolated.
Compounds. A. Typical forms. The typical com- pounds of five elements of the yttrium group are given on the next page.
B. Characteristics. The existence of the earths of er- bium, terbium, ytterbium, scandium, and samarium has
* References: Mosander and Delafontaine, J. pr. Chem. xciv, 297; Bahr and Bunsen, Ann. Chem. Pharm. cxxxvii, i ; Auer v. Welsbach, Monatshefte f. Chem. iv, 630; Waage, Chem. Ztg. (1895), 1072; Drossbach, Ber. Dtsch. chenu Ges. xxix, 2452; Urbain, Chem. Ztg. (1898), 271; Dennis and Dales, Jour. Amer. Chem. Soc. xxiv, 401.
THE GADOL1NITE OR YTTRIUM EARTHS.
29
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3° THE RARER ELEMENTS.
been quite definitely established. The other members of the gadolinite group are still more or less in doubt. Of the five mentioned above, the first four closely resemble yttrium. Solutions of terbium, ytterbium, and scandium salts give no absorption spectra. The salts of erbium are of a rosy tint, and give an absorption spectrum. The double sul- phates of these four elements respectively with potassium sulphate are soluble in a solution of potassium sulphate, the ytterbium and scandium salts being more soluble, how- ever, than those of erbium and terbium. Samarium re- sembles cerium. Its salts are yellowish, and the solutions give an absorption spectrum. The double sulphate with potassium sulphate is insoluble in a solution of potassium sulphate.
CERIUM, Ce, 140.
Discovery. In the course of the analysis of a mineral from Riddarhyttan, Sweden, in 1803, Klaproth discovered an earth which, while resembling yttria in many of its reactions, differed from it in being insoluble in carbonate of ammonium, and in acquiring, when ignited, a light brown color. Because of this latter peculiarity, the name Ochroite suggested itself to him, from 'caXpoz, yellow brown (Phil. Mag. xix, 95). At the same time, and independently of Klaproth, Berzelius and Hisinger made the same discovery. Their name for the new element was Cerium, chosen in honor of the discovery of the planet Ceres by Piazzi in 1801 (Phil. Mag. xx, 155; xxn, 193).
Occurrence. Cerium is found in many minerals, asso- ciated, usually, with lanthanum and didymium.
Contains Ce,O, Di2O3+La2CX
Cerite, (Ca,Fe) (CeO) (Ce2 • 3OH) (SiO,),. . 24-65 % 7-35 %
n in Allanite or orihite, HRR3Si3O13 1-18% 1-16%
Gadolinite, Be2FeY2Si2O10 1-10% 2-20%
CERIUM. 31
Contains Ce203
Cappelenite, complex silicates 1-2% 2- 3%
Melanocerite, " 20-2 1 % 20-2 1 %
Caryocerite, 14-1 5 % 20-2 1 %
Tritomite, M 19-21% 21-26%
Tscheffkinite, " silico-titanates. . 12-20% 17-20%
Johnstrupite, " " " 12-13% *
Mosandrite, " " " 16-26% *
Rinkite, " " " 21-22% * Mackintoshite,
U02-3Th02.3Si02.3H20. . . . 45-46%t
Monazite, (Ce, La, Di)PO4 16-36% 20-24%
Churchite, R3P208-4H20 50
Xenotime, YPO4 0-11% *
Rhabdophanite, RPO4 -H2O 23% 55%
Fluocerite, R2O2 -4RF3 39~46% 3o-36%
Tysonite, (Ce, La, Di)F3 40% 3o%
in
Yttrocerite, (2RF3 • 9CaF2) • 3H20 5 % 5 %
Parisite, (CaF) (CeF)Ce(CO3)3 38% 15%
Bastnaesite,
(Ce, La, Di)2C3Oe.(Ce, La, Di)F3. . 28-41% 35~46%
Lanthanite, La2(CO3)3-9H20 52%
Samarskite, R3R2(Nb,Ta)6O21 2-5% *
IK
Fergusonite, R(Nb,Ta)O4 0-9% *
m in
Euxenite, R(NbO3)3.R2(TiO3)3.|H2O. 2- 8%
Zirkelite, (Ca,Fe)O • 2(Zr, Ti, Th)O2. . . 2- 3%
Polycrase,R(Nb03)3.2R(Ti03)3-3H20 2- 3% Polymignite,
SRT^-sRZrO^^Nb.Ta)^.-.-- 6% 5%
III III
^Eschymte, I^Nbp13-I^(Ti,Th)5O13. . 18% 5%
* Included under Ce2Os. f Ce2O3+ ThO2.
32 THE RARER ELEMENTS.
Contains Ce2O3
Hielmite, formula doubtful 0.5-1%
Annerodite, " " . '. 2-3%
ii in Yttrotantalite, RR2(Ta,Nb)4O15-4H2O. o- 2%
Sipylite, complex niobate i% 8%
Pyrochlore, RNb2O6-R(Ti,Th)O3 5- 7%
Arrhenite, formula doubtful 2~ 3 % *
Extraction. Cerium is generally extracted from cerite through decomposition of the mineral by heating it with strong sulphuric acid (vid. Experiment 33). The decom- position may be accomplished also by the action of a mix- ture of strong hydrochloric and nitric acids, but better results may be expected by the former method.
The Element. A. Preparation. Elementary cerium may be obtained (i) by reducing the chloride with sodium or potassium (Mosander) ; (2) by subjecting the double chloride of cerium and sodium to electrolysis (Pogg. Annal. CLV, 633).
B. Properties. In appearance cerium resembles iron. While fairly stable in dry air, it oxidizes quickly in moist air. It takes fire more easily than magnesium, and melts at a lower temperature than silver and at a higher temperature than antimony. It is soluble in dilute acids, but is not attacked by concentrated sulphuric or nitric acid. It com- bines with chlorine, bromine, and iodine, forming salts. Its specific gravity is 6.6.
Compounds. A. Typical forms. The following are typ- ical forms of the two classes of cerium compounds:
Oxides Ce2O3 CeO2
Hydroxides Ce2O3-6H2O 2CeO2-3H2O
Carbonates Ce2(CO3)3+ 5H2O Ce(CO3)2+ o.5H2O
Chloride CeCl3
Bromide CeBr3
Iodide CeI3
Perchlorate Ce(ClO4) 3+ 8H2O
* Included under Ce2O3.
CERIUM. 33
Bromate ........ Ce(BrO3)3-f9H2O
lodate .......... Ce(IO3)3+ 2H2O
Fluorides ....... CeF3 CeF4+ HaO
Cyanide ......... Ce(CN)3
Ferrocyanides. . . Ce4(FeCflN8)3+ 3oH2O
CeKFeC6Nfl+3H20 Ferricyanide ..... CeFeC8N6+ 8H2O
Sulphocyanide . . Ce(CSN)3+ 7H2O Sulphide ........ Ce2S3
Sulphite ........ Ce2(S03)3+ 3H2O
Sulphates ....... Ce2(SO4)3+ 3, 5, 6, 8, 9, and Ce(SO4)2 + 4H2O
i2H20 Double sulphates. Ce2(SO4)3 • 3K2SO4+ 2H2O CeCSOJz • 2K2SO4+ 2H2O
Ce2(S04)3 • 3Na2S04+ 2H2O
Ce2(S04)3-(NH4)2S04+8H20 Nitrates ........ Ce(NO3)3-f 6H2O Ce(NO3)4
Double nitrates. .Ce2(NO3)6-3Zn(NO3)2-|- 2Ce(NO3)4-4KNO3+3H2O
Ce2(N03V 3Co(N03)2+ 2Ce(NO3)4.4(NH4)NO3+
24H2O, etc. 3H2O
Phosphates ...... CePO4 (CeO2)4 • (P2O5)e+ 26H2O
Oxalate ......... Ce2(C2O4)3
Carbide .........
B. Characteristics. Cerium exists in compounds in two conditions of oxidation. The higher or eerie salts are easily reduced to the lower or cerous condition by the ordinary reducing agents (e.g. H2S, SO2, H2C2O4, etc.), and the cerous salts may be oxidized* to the eerie condition by oxidizing agents (e.g. PbO2 + HNO3, H2O2, KMn04, etc.). In general the cerous salts are colorless, and the eerie yellow. The lower oxide of cerium, (Ce2O3), on ignition goes over to the higher condition, (CeO2). The cerous salts are the more stable, and consequently they form the greater number. They resemble the yttrium salts in many of their reactions, and are distinguishable from them chiefly by the formation of the double sulphates with sodium sulphate and potas- sium sulphate respectively, by the comparative insolubility of the carbonate in ammonium carbonate, and by the possi- bility of oxidation to a higher condition. Solutions of pure cerium salts give no absorption spectra.
34 THE RARER ELEMENTS.
Estimation. A. Gravimetric. Cerium is usually deter- mined gravimetrically as the dioxide, (CeO2), obtained by the ignition of the hydroxide or the oxalate.
B. Volumetric, (i) When eerie oxide, (CeO2), is treated with hydrochloric acid in the presence of potassium iodide, iodine is set free, according to the following equation :
2CeO2 + 8HC1 + 2KI = 2CeCl3 + 4H2O + 2KC1 + 12.
The iodine may be estimated in acid solution by stand- ard thiosulphate, or in alkaline solution by standard arsenious acid (Bunsen, Ann. Chem. Pharm. cv, 49 ; Brown- ing, Amer. Jour. Sci. [4] vui, 451).
(2) When cerium oxalate is dissolved in sulphuric acid the oxalic acid may be readily determined by potassium permanganate, and the amount of cerium present may be thus estimated (Stolba, Zeitsch. anal. Chem. xix, 194; Browning, Amer. Jour. Sci. [4] vm, 457).
(3) When yellow eerie compounds are treated with hydrogen dioxide in acid solution, they are reduced to cerous compounds, with bleaching of color (Knorre, Zeitsch. angew. Chem. (1897), 685):
2Ce (S04)2 + H202 = Ce2(S04)3 + H2SO4 + O2.
Separation. Cerium falls into the analytical group with aluminum, iron, etc. Together with the other rare earths it may be separated from these by oxalic acid or oxalate of ammonium. For separation from the yttrium earths, vid. page 24.
Cerium may be separated from lanthanum and didy- mium * by the following methods : ( i ) by treating the hy- droxides suspended in a solution of caustic potash with
* For an instructive review of the methods for the separation of cerium, lanthanum, and didymium, see P. Mengel, Zeitsch. anorg. Chem. xix (1899), 67.
CERIUM. 35
chlorine gas, as in Experiment 33 (Mosander, J. pr. Chem. xxx, 267) ; (2) by treating a neutral solution of the cerium earths with an excess of a hypochlorite and boiling, thus precipitating eerie oxide (Popp, Ann. Chem. Pharm. cxxxi, 359); (3) by treating a solution of the cerium earths with sodium peroxide, in place of the hypochlorite in (2) (O. N. Witt, Chem. Ind. (1896), u, 19); (4) by treating the oxa- lates of the cerium earths with warm dilute nitric acid; thus separating the cerium as basic nitrate (Auer von Welsbach, Monatshefte f. Chem. v, 508) ; (5) by treating a solution of the salts with hydrogen dioxide in the presence of magnesium acetate (Meyer and Koss, Ber. Dtsch. chem. Ges. xxxv, 672).
From thorium cerium may be separated (i) by repeated precipitations on boiling with sodium thiosulphate (Fre- senius and Hintz, Zeitsch. anal. Chem. xxxv, 543) ; (2) by boiling with potassium nitride (Dennis and Kortright, Amer. Chem. Jour, xvi, 79) :
Th(NO3)4 + 4KN3 + 4H2O = Th(OH)4 + 4KNO3 + 4HN3 ;
(3) by boiling a nearly neutral solution of the chlorides with copper and cuprous oxide (Lecoq de Boisbaudran, Compt. rend, xcix, 525) ; (4) by the action of fumaric acid in 40% alcohol upon solutions of the salts in 40% alcohol (Metzger, Jour. Amer. Chem. Soc. xxiv, 901). In all of these methods the thorium is precipitated.
Cerium is separated from zirconium by fusion of the oxides with acid potassium fluoride, and extraction with water and a little hydrofluoric acid; the potassium fluo- zirconate is dissolved, and the thorium and cerium remain * (Delafontaine, Chem. News LXXV, 230).
Experimental Work. Vid. Lanthanum and Didymium.
* For the action of organic bases as precipitants of the rare earths, vid. Jefferson, Jour. Amer. Chem. Soc. xxiv, 540; Baskerville, Science, New Series, xvi, 215; Kolb, J. pr. Chem. [2] LXVI, 59; Allen, Jour. Amer. Chem. Soc. xxv, 421.
THE RARER ELEMENTS.
LANTHANUM, La, 138.77; DIDYMIUM, Di, 142.3.
(PRASEODYMIUM, Pr, 140.5; NEODYMIUM, Nd, 143.6.)"
Discovery. In 1839 Mosander found that when the nitrate of cerium had been ignited, he was able to extract from it by very dilute acid an earth which differed in prop- erties from that of cerium, while from the portion remain- ing undissolved he obtained the reactions of the cerium earth. He supposed the unknown substance of the newly discovered earth to be an element, and named it Lan- thanum, from \avQavziv, to hide (Pogg. Annal. XLVI, 648; Liebig, Annal. xxxn, 235).
In 1841, while engaged in further work upon the extrac- tion of mixtures of cerium and lanthanum oxides by dilute nitric acid, he succeeded in separating from the lanthanum oxide another earth, rosy in color, going over to dark brown on being heated. Reserving for the residual oxide the original name Lanthanum earth, he called the base of the new oxide Didymium, from didvjuos, twin, — a name sug- gested by its close relationship to lanthanum and its almost invariable occurrence with it (Pogg. Annal. LVI, 503).
In 1885 Auer von Welsbach announced that by long- continued fractional crystallization of the double nitrates of ammonium with lanthanum and didymium in the pres- ence of strong nitric acid, he had separated didymium into two elements (Sitzungsber. d. k. Acad. d. Wiss. (1885) xcn, Heft I, n, 317; Ber. Dtsch. chem. Ges. xvin, 605). The lanthanum crystallized out first, and afterward the decomposition of the didymium took place. To these new elements he gave the names Praseodymium (Ttpdcriros, leek-green) and Neodymium (veos, new).
In 1888 Kriiss and Nilson stated, as the result of their work on the absorption spectrum of didymium, that they
LANTHANUM ; DIDYM1UM. 37
had discovered indications of the presence of no less than eight elements (Ber. Dtsch. chem. Ges. xx, 2134, 3067). These results, however, have not as yet been fully con- firmed. At the present time the existence of praseodym- ium and heodymium is generally accepted.
(Though the term "didymium" does not designate an element, it is still in general use, and for the sake of convenience it is employed in the following pages. While there is a considerable body of information concerning didymium, its constituent elements have not yet been so fully studied, — perhaps because of the long and tedious operation involved in their separation. For that reason, at all events, no experimental work on them is given in this book.)
Occurrence. Lanthanum and didymium are found al- most invariably associated with cerium (vid. Occurrence of Cerium).
Extraction. In the process of extracting cerium from cerite (vid. Experiment 33), the oxalates of cerium, lan- thanum, and didymium are precipitated together. Lan- thanum and didymium must next be separated from cerium, and then from each other. Afterward didymium may be decomposed into its two constituents. Several methods of accomplishing these three steps are indicated under Separation of Cerium, and of Lanthanum and Didy- mium.
The Elements. I. LANTHANUM. A. Preparation. The element lanthanum may be obtained (i) by reducing the chloride with potassium; (2) by subjecting the double chloride of lanthanum and sodium to electrolysis.
B. Properties. Lanthanum is a metallic element of a lead-gray color. It decomposes cold water slowly and hot water more rapidly, with the evolution of hydrogen. It oxidizes easily in the air. Its specific gravity is from 6.04 to 6.19.
38 THE R4RER ELEMENTS.
II. DIDYMIUM. Elementary praseo- and neodymium have not been isolated.
A. Preparation. Didymium may be prepared from the salts by the methods indicated for lanthanum (vid. Prep- aration of Lanthanum).
B. Properties. Metallic didymium is yellowish white. It decomposes cold water slowly and oxidizes in the air. Its specific gravity is 6.54.
Compounds. A. Typical forms. The following are typ- ical compounds of lanthanum and didymium:
Oxides La2O8 Di2O3
Di205
Hydroxides La(OH)3 Di(OH)3
Chlorides LaCl3+ 7H2O DiCl3+ 6H2O
Oxychlorides. . . .IXOClj) Di(OCl)3
Chlorate La(ClO3)3
Perchlorates La(ClO4)3+ 9H2O Di(ClO4)3+ 9H2O
Bromides LaBr3-f- 7H2O DiBr3+ 6H2O
Bromates La(BrO3)3+9H2O Di(BrO3)3+9H2O
lodates La2(IO3)6+ 3H2O Di(IO3)3+ 6H2O
Periodates La(IO4)3+ 2H2O Di(IO4)3+4H2O
DiO(I04)+4H20
Sulphites La2(SO3)3+ 4H2O Di2(SO3)3-f- 6H2O
Sulphates La2(SO4)3+ 9H2O Di2(SO4)3-f 8H2O
Double sulphates. La2(SO4)3 • 3K2SO4 Di2(SO4)3 • 3K2SO.
La2(SO4)3 • Na2SO4-f 2H2O Di2(SO4)3 . Na2SO4+ 2H2O
La2(S04)3 • (NH4)2S04+ 8H2O Di2(SO4)3 i (NH4)2SO4+ 8H2O
Dithionates La2(S2O6)3 + i6H2O Di2(S2O6)3 + 24H2O
Selenites La2(SeO3)3+ 9H2O Di2(SeO3)3+ 6H2O
Seleniates La2(SeO4)3+ 6H2O Di2(SeO4)3+ 8H2O
Double seleniates. La2(SeO4) 3 • K2SeO4+ 9H2O Di2(SeO4)3 - K2SeO4
La2(SeO4)3 • Na2SeO4+ 4H2O Di2(SeO4)3 • Na2SeO4
La2(Se04)3 . (NH4)2SeO4+ Di2(SeO4)3 • (NH4)2SeO4 9H20
Nitrates La(NO3)3+6H2O Di(NO3)3+6H2O
Phosphates LaPO4; also meta and pyro DiPO4+H2O; also meta and
forms PYr° forms
Arseniates La2H3( AsO4)3 Di2H3(AsO4)3
Arsenites La2H3(AsO3)3 Di2H3(AsO3)3
Carbonates La2(CO3)3+ 3H2O Bi2(CO3)3+ 6H2O ; also double
salts with K, Na, and NH« carbonates
LANTHANUM; D1DYMIUM. 39
Oxalates ........ La2(CaO4)s Di2(C2O4)a
Chromates ...... La2(CrO4)3 Di2(CrO4)3
Molybdates ...... LaH3(MoO4)s DiH^MoOJa
Tungstates ...... La2(WO4)3 Di(WO4)3
Sulphides ....... La2S3 Di2S3
The following compounds of praseo- and neodymium have been described:
Oxides .......... Pr2O3 • Nd2O3
Pr407
Pr204 Nd204?
Pr2O5? Nd2O6?
Carbonate ....... Pr2(CO3)3-f- 8H3O
Chlorides ........ PrCl3+ 7H2O NdCl3+ 6H2O
Bromide ........ PrBr3-|- 6H2O
Sulphates ....... Pr2(SO4)3+ 8H2O Nd2(SO4)3+ 8H2O
Pr202S04 Nd202S04
PrH3(S04)3 NdH3(S04),
Double sulphates . Pr2(SO4)3 - 3K2SO4+ H2O
Pr2(S04)3-(NH4)2S04+8H20 Sulphides ....... Pr2S3 Nd2S8
Selenite ......... Pr2(SeO3)3-H2SeO3+3H2O
Seleniate ........ Pr2(SeO4)3+ 8H2O
Double seleniate . Pr2(SeO4)3 • K2SeO4+ 4H2O
Nitrates ........ Pr(NO3)3+ 6H2O Nd(NO3)3
Double nitrates. . Pr(NO3)3 • 2(NH4)NO3+ 4H2O
Pr(N03)3-2NaN03+H20 Double cyanide. . 2Pr(CN)3- Pt(CN)2+ i8H3O Oxalate ......... Pr2(C2O4)3+ ioH2O
B. Characteristics. The compounds of lanthanum, di- dymium, and cerium in the cerous condition are very similar in their behavior toward chemical reagents. The compounds of lanthanum and didymium may be distin- guished from those of cerium by the absence of yellow color on the addition of oxidizing agents, — a color character- istic of the higher oxide of cerium. Lanthanum may be distinguished from didymium by the colorlessness of its salts and by the absence of an absorption spectrum. Di- dymium salts in general are of a rosy color and give a distinctive absorption spectrum.
40 THE RARER ELEMENTS.
The compounds of praseo- and neodymium have not been sufficiently studied to allow any detailed description of their characteristics to be given. Neodymium salts are rose-colored and are very similar in appearance and in behavior to the salts of the original didymium. The oxide Nd2O3 is bluish. Praseodymium salts are green. While their chemical form resembles closely the form of the neodymium salts, higher oxides are definitely known in the case of praseodymium. The ordinary oxide Pr2O3 is greenish white ; the higher oxide Pr407 is nearly black. Each of the two elements has distinctive spectra, spark and absorption. Mixed, the elements give the didymium spectrum.
Estimation. Like cerium, lanthanum and didymium are generally estimated as oxides, obtained by ignition of the hydroxides or oxalates.
Separation. A. Lanthanum from didymium. Lantha- num may be separated from didymium (i) by dissolv- ing the sulphates in water at 9° C. and gradually raising the temperature, — the lanthanum sulphate separating first (Hermann, J. pr. Chem. LXXXII, 385) ; (2) by heating the nitrates at 4oo°-5oo° C. and extracting with water, — the didymium tending to form an insoluble basic nitrate (Damour and Deville, Bull. Soc. Chim. d. Paris n, 339) ; (3) by dissolving half of a given amount of the oxides in warm dilute nitric acid, then adding the other half, with constant stirring, cooling the mass, and extracting with water (vid. Experiment 33). The didymium will be found in the residue (Auer von Welsbach, Monatshefte f. Chem.
v, 508).
B. Praseodymium from neodymium. Didymium may be separated into its two constituents (i) by making several hundred fractional crystallizations, first of the double nitrate of ammonium and didymium and later of the double nitrate of sodium and didymium, in the presence of
EXPERIMENTAL WORK ON CERIUM, LANTHANUM, ETC. 41
nitric acid, — the neodymium salt being the more soluble (Auer von Welsbach, Sitzungsber. d. k. Acad. d. Wiss. (1885) xcn, Heft I, n, 317; (2) by allowing nitric acid to act upon the oxalates, — the praseodymium salt being the more soluble (Scheele, Ber. Dtsch. chem. Ges. xxxn, 417) ; (3) by treating the sulphates with water, — the praseo- dymium sulphate being the more soluble (Muthmann and Rolig, Ber. Dtsch. chem. Ges. xxxi, 1718); (4) by making fractional precipitations of a solution of didymium nitrate by means of sodium acetate and hydrogen peroxide, — the praseodymium separating first (Meyer and Koss, Ber. Dtsch. chem. Ges. xxxv, 676) ; (5) by saturating a cold concentrated solution of citric acid with the hydroxides free from ammonia and excess of water, then filtering and heating, — the green citrate of praseodymium being precipitated, insoluble in hot water (Baskerville, Science, New Series, xvi, 214).
EXPERIMENTAL WORK ON CERIUM, LANTHA- NUM, AND DIDYMIUM.
Experiment 33. Extraction of cerium, lanthanum, and didymium salts from cerite (Ca,Fe)(CeO)(Ce2«3OH)(SiO3)3. Treat 25 grm. of finely powdered cerite with common sulphuric acid and stir until the mass has the con- sistency of thick paste. Heat until the excess of sul- phuric acid is removed and then keep the mass for some time at low redness. Cool, pulverize, and digest with cold water until no further precipitate appears upon the addition of ammonium oxalate to a few drops of the extract. Pass hydrogen sulphide into the solution to remove traces of bismuth and copper. Filter, and to the filtrate add oxalic acid to complete precipitation of the oxalates of cerium, lanthanum, and didymium. Ignite the oxalates, and dissolve in hydrochloric acid the oxides obtained. To this solution add potassium hydroxide
42 THE RARER ELEMENTS.
until the precipitation of the hydroxides is complete. Make up the volume of the liquid in which the hydroxides are suspended to about 200 cm.3 Add about 5 grm. of potassium hydroxide to insure an excess, and pass a slow current of chlorine gas through, stirring from time to time, until the liquid is no longer alkaline in reaction and the precipitate has assumed a deep-yellow color. By this process the cerium hydroxide is oxidized to the dioxide, which remains undissolved, and the lanthanum and didy- mium hydroxides are dissolved. When the separation is complete, a portion of the washed precipitate dissolved in hydrochloric acid should give no evidence of the presence of didymium, — for example, no absorption spectrum (vid. Experiment 43). The absence of didymium at this point is considered sufficient evidence of the absence of lanthanum. To the solution containing the lanthanum and didymium, the cerium dioxide having been removed by filtration, add oxalic acid until the precipitation is complete. Filter off the oxalates, wash, dry, and ignite. Dissolve one half of the oxides obtained by this process in the least possible amount of warm, dilute nitric acid, and add the remainder of the oxides to the solution. Stir thoroughly, and when the mass is cool extract with water. The didymium tends to be in the residue and the lanthanum in solution.
Experiment 34. Reduction and oxidation of cerium compounds, (a) To a small portion of the carefully washed cerium dioxide obtained in the previous experiment add a little hydrochloric acid diluted with an equal volume of water and boil. Note the evolution of chlorine and the ultimate colorless solution of cerium chloride, (CeCl3).
(b) To a portion of the solution obtained in (a) add a few drops of ammonium hydroxide in excess and some hydrogen dioxide. Note the orange-yellow precipitate (CeO3?). Other oxidizing agents, such as sodium hypo chlorite, sodium peroxide, lead dioxide, potassium per-
EXPERIMENTAL WORK ON CERIUM, LANTHANUM, ETC. 43
manganate, etc., may be used. Boil the solution holding the precipitate in suspension and note that the deep-yellow color changes to a lighter yellow. The precipitate becomes essentially the dioxide, (CeO2).
(c) To another portion of the washed cerium dioxide from Experiment 33 (2CeO2-3H2O) add hydrochloric acid as before, and also a crystal of potassium iodide in the cold. Note the liberation of iodine according to the reaction 2CeO2 + 8HC1 + 2KI = 2CeCl3 + 2KC1 + 12 + 4H2O.
Experiment 35. Precipitation of cerous hydroxide, (Ce(OH)3). (a) To a solution of cerium chloride add sodium, potassium, or ammonium hydroxide in solution. Note the insolubility of the hydroxide in excess of these reagents.
(b) Repeat the experiment with tartaric acid present in the solution.
Experiment 36. Precipitation of cerous carbonate, (Ce2(CO3)3). (a) To a solution of cerium chloride add a solution of sodium or potassium carbonate. Note the comparative insolubility in excess.
(b) Repeat the experiment, using ammonium carbonate as the precipitant.
(c) Try the action of the common acids upon the car- bonate of cerium.
Experiment 37. Precipitation of cerium oxalate, (Ce2(C2O4)3). (a) To a solution of a cerium salt add oxalic acid or an oxalate. Note the crystalline character of the pre- cipitate, especially after the liquid has been stirred and boiled.
(b) Try the action of hydrochloric acid upon cerium oxalate.
Experiment 38. Precipitation of the double sulphate of cerium and potassium or sodium, (Ce2(S04)3-3K2SO4 or Ce2(SO4)3-Na2SO4). To a few drops of a concentrated solution of a cerous salt add a small portion of a saturated solution of sodium or potassium sulphate.
44 THE RARER ELEMENTS.
Experiment 39. Precipitation of cerium phosphate, (CePO4). (a) To a solution of a cerous salt add sodium phosphate in solution.
(6) Try the action of hydrochloric and acetic acids upon separate portions of the precipitate.
Experiment 40. Precipitation of cerous fluoride, (CeF3). To a solution of cerium chloride add potassium fluoride in solution.
Experiment 41. Precipitation of the ferrocyanide of cerium, (Ce4(FeC6N6)3). (a) To a solution of cerium chloride add potassium ferrocyanide.
(6) Note that potassium ferricyanide gives no pre- cipitate.
Experiment 42. Comparison of lanthanum and didym- ium with cerium. (a) Perform Experiments 35 to 41 inclusive upon dilute solutions of lanthanum and didym- ium salts.
(6) Note that pure lanthanum and didymium salts give no change of color with oxidizing agents. Compare with cerium salts (vid. Experiment 34).
Experiment 43. Didymium absorption spectrum. Place a solution of a didymium salt between the slit of the spectroscope and a luminous flame. Note the dark bands. Observe that cerium and lanthanum salts in solution show no absorption bands when free from didymium.
Experiment 44. Negative test of the salts of cerium, lanthanum, and didymium. Note that hydrogen sulphide gives no precipitate with salts of this group. Ammonium sulphide precipitates the hydroxides, not the sulphides.
THORIUM, Th, 232.5.
Discovery. As early as the year 1818 Berzelius, after working on a mineral from Fahlun, Sweden, believed that he had discovered a new earth (Annal. der Phys. u. Chem.
THORIUM. 45
(1818) xxix, 247). He gave it the name Thoria, from Thor, son of the Scandinavian war god Odin. Some years later however, he identified the supposed new earth as chiefly a basic phosphate of yttrium (Pogg. Annal. iv, 145). In 1828 Esmark discovered, near Brevig, Norway, the mineral since known as thorite. From it Berzelius isolated an unknown earth; its similarity to the substance described by him some ten years earlier prompted the name Thoria (Pogg. Annal. xvi, 385).
Occurrence. Thorium is found in combination in cer- tain rare minerals :
Contains ThO2
Thorite or orangite, ThSiO4 48-72%
Yttrialite, R2O3 - 2SiO2 12 %
Zircon, ZrSiO4. 0-2%
ii in Orthite or allanite, HRR3Si3O13 0-3%
Mackintoshite, UO^ThO^SiO^H.O 45-46%*
Thorogummite, UO3 - 3ThO2 • 3SiO2 • 6H20 41-42 %
Caryocerite, complex silicates : 13-14%
Tritomite, " " 8-9%
Zirkelite, (Ca,Fe)O - 2(Zr,Ti,Th)O2 7-8%
Monazite, (Ce^a.D^PO, 0-18%
Xenotime, YPO4 0-3%
in in JEschynite, RJNb4Ou-Rt('Ii,Th)iOu 15-1?%
Ill III
Euxenite, R(NbO3)3 - R2(TiO3)3 • f H2O o- 6 %
Tscheffkinite, complex silico-titanates 0-21 %
Pyrochlore, RNbaO6-R(Ti,Th)O3 0-8%
n in
Samarskite, R^Nt^Ta)^ o- 3%
o
Annerodite, formula doubtful 2- 3%
Polymignite, 5RTiOs • 5RZrO3 • R(Nb,Ta)aO6 3-4%
*ThO,+ Ce208.
46 THE RARER ELEMENTS.
Extraction. Two common methods for the extraction of thorium salts are here indicated:
(1) From thorite. The mineral is decomposed by heating it with sulphuric acid (vid. Experiment 33). After the extraction of the sulphate with cold water, the solution is heated to 100° C. and an impure sulphate of thorium comes down. By repeated solution of the precipitate in cold water and reprecipitation by means of heat a pure sulphate is finally obtained (Delafontaine, Ann. Chem. Pharm. cxxxi, 100).
(2) From monazite. The mineral is decomposed by sulphuric acid and the oxalates are precipitated by oxalic acid (vid. Experiment 45).
The Element. A. Preparation. Elementary thorium may be obtained (i) by heating the double chloride of thorium and potassium with metallic sodium (Nilson); (2) by reducing the double fluoride of potassium and thorium with potassium.
B. Properties. Thorium is known in two forms, (i) that of a grayish, glistening powder, and (2) crystalline. It is stable in the air, and does not decompose water, even at 1 00° C. When heated in a current of chlorine, bromine, or iodine it glows and forms the salt. It is soluble in dilute hydrochloric and sulphuric acids, in concentrated sulphuric acid with the liberation of sulphur dioxide, and in aqua regia. It is acted upon very slowly by nitric acid, and is not attacked by the alkali hydroxides. The specific gravity of thorium in the amorphous condition is 10.97; in crystalline form 11.2.
Compounds. A. Typical forms. The following are typ- ical compounds of thorium:
Oxides, ThO2; Th2O7. Hydroxide, Th(OH)4. Chlorides, ThCl4; also double salts with KC1 and NH4C1.
THORIUM. 47
Bromide, ThBrr
Iodide, ThI4.
Fluoride, ThF4 + 4H2O.
Chlorate, Th(ClOs)4.
Perchlorate, Th(ClO4)4.
Bromate, Th(BrO3)4.
lodate, Th(IO3)4.
Sulphite, Th(SO3)2 + H2O.
Sulphates, Th(SO4)2 + 9H2O; also double salts with K2SO4;
Na2SO4; and (NH4)2SO4. Selenite, Th(SeO3)2 + H2O. Seleniate, Th(SeO4)2 + 9H2O. Nitrate, Th(NO3)4 + i2H2O. Phosphate, Th3(PO4)4 + 4H2O. Pyrophosphate, ThP2O7 + 2 H2O. Ferrocyanide, ThFe(CN)6 + 4H2O. Silicate, ThSi04.
Carbonates, Th(CO3)2 ; Th(CO3)2 • sNa2CO3 + 1 2H2O. Oxalate, Th(C2O4)2 + 2H2O. Sulphide, ThS2.
B. Characteristics. The compounds of thorium resem- ble in chemical form those of cerium in the eerie con- dition. Thorium resembles cerium also in having a hy- droxide insoluble in the alkali hydroxides, and in forming a double sulphate with potassium sulphate, insoluble in excess of that precipitant. The salts of thorium are colorless except where the element is combined with an acid having a color of its own. Possibly the most distinctive reactions of thorium compounds are the ready formation of a soluble double oxalate when ammonium oxalate is added in excess to a thorium salt in solution, and the precipitation of the hydroxide when a solution of a thorium salt is boiled with potassium hydronitride (Dennis and Kortright, Amer. Chem. Jour, xvi, 79).
Estimation. Thorium is ordinarily estimated as the
48 THE RARER ELEMENTS.
oxide (ThO2), obtained by ignition of the hydroxide, the nitrate, or the oxalate.
Separation. Thorium is a member of the aluminum group. Together with the rare earths cerium, yttrium, zirconium, etc., it may be separated from other members of the group by oxalic acid. Methods for its separation from yttrium and cerium have already been given (vid. pages 24 and 35).
From zirconium thorium may be separated (i) by the action of acids upon the potassium double sulphates, — • the zirconium salt being the more soluble 5(2) by the action of an excess of oxalic acid upon the oxalates, — the zir- conium oxalate dissolving first; (3) by fusion with acid potassium fluoride; (4) by the action of dimethylamine upon solutions of the salts, — thorium hydroxide being pre- cipitated (Kolb, J. pr. Chem. [2] LXVI, 59).
EXPERIMENTAL WORK ON THORIUM.
Experiment 45. Extraction of thorium oxide from mona- zite. Treat 25 grm. of finely ground monazite with com- mon sulphuric acid according to the method already described (vid. Experiment 33). Precipitate the oxalates with oxalic acid, — not ammonium oxalate, — boil, and col- lect on a filter. Treat the precipitate with a large excess of ammonium oxalate and boil. Cool, filter, and to the filtrate add hydrochloric acid. Collect and ignite the oxalate of thorium thus precipitated.
Note. This method may be employed for the extraction of thorium from discarded Welsbach-light mantles.
Experiment 46. Precipitation of thorium hydroxide, (Th(OH)4). (a) To a solution of a thorium salt add sodium, potassium, or ammonium hydroxide. Note the insolu- bility of the hydroxide in excess of the precipitant.
(b) To a solution of a thorium salt add sodium thio- sulphate in solution and boil.
EXPERIMENTAL WORK ON THORIUM. 49
Experiment 47. Precipitation of thorium carbonate, (Th(CO8)2). (a) To a solution of a thorium salt add potassium or sodium carbonate. Note the solubility of the precipitate in excess and the reprecipitation on boiling.
(b) Repeat, using ammonium carbonate.
(c) Note the solvent action of the common acids upon thorium carbonate.
Experiment 48. Precipitation of the oxalate of thorium, (Th(C2O4)2 + 2H2O). (a) To a solution of a thorium salt add a solution of oxalic acid. Note the insolubility in excess of the precipitant.
(b) Repeat, using ammonium oxalate as the precipitant. Note the solubility in excess, especially on warming, and the reprecipitation upon the addition of hydrochloric acid.
(c) Try the solvent action of ammonium acetate upon thorium oxalate.
Experiment 49. Precipitation of the double sulphate of potassium and thorium, (Th(SO4)2-2K2SO4 + 2H2O or Th(SO4)2 - 4K2SO4 + 2H2O) . Saturate a solution of a thorium salt with potassium sulphate. (The corresponding sodium salt (Th(SO4)2-Na2SO4 + 6H2O) is somewhat soluble in excess of sodium sulphate.)
Experiment 50. Precipitation of thorium phosphate, (Th3(PO4)4 + 4H2O). To a solution of a thorium salt add sodium phosphate in solution. Orthophosphoric acid is said to precipitate an acid phosphate (ThH2(PO4)2).
Experiment 51. Precipitation of thorium fluoride, (ThF4 + 4H2O). To a solution of a thorium salt add a solution of potassium fluoride. Double salts with thorium fluoride may also form (#KF-yThF4 typical).
Experiment 52. Precipitation of thorium ferrocyanide , (ThFe(CN)8 + 4H2O). To a solution of a thorium salt add a solution of potassium ferrocyanide. Note the absence of precipitation with potassium ferricyanide.
Experiment 53. Action of hydrogen peroxide upon
50 THE RARER ELEMENTS.
salts of thorium. To a solution of a thorium salt add a little hydrogen peroxide, and warm.
Experiment 54. Negative test of thorium salts. To a solution of a thorium salt add hydrogen sulphide. Note that ammonium sulphide precipitates the hydroxide, not the sulphide.
ZIRCONIUM, Zr, 90.7.
Discovery. While engaged in the analysis of the zircons, in 1788, Klaproth found one variety containing 31.5% of silica, 0.5% of the oxides of iron and nickel, and 68% of an earth which differed from all earths pre- viously known to him. He observed that it was soluble in the acids, but insoluble in the alkalies, in the latter respect differing from alumina (Ann. de Chim. i, 238). The fact that zircon was the source of the new earth sug- gested the name Zirconium for the element.
Occurrence. Zirconium is found combined, widely dif- fused, but always in small quantities.
Contains ZrO2
Zircon, ZrSiO4 61-67%
Rosenbuschite, 6CaSiO3-2Na2ZrO2F2-(TiSiO3-Ti03) 18-20%
Lavenite, R(Si,Zr)O3-Zr(SiO3)2-RTa2O6 28-32%
Wohlerite, i2R(Si,Zr)O3-RNb,O6 15-23%
Hainite, allied to lavenite, etc .undetermined
Hiortdahlite, 4Ca(Si,Zr)O3-Na2ZrO2F2 21-22%
Eudialyte, Na13(Ca,Fe)6Cl(Si,Zr)20O52 "-17%
Catapleiite, H4(Na2,Ca)ZrSi3On 29-40%
Elpidite, H6Na2ZrSi6O18 20-21 %
Eucolite, vid. Eudialyte 12-16%
Auerbachite, vid. Zircon 38-69%
Cyrtolite, " " 41-42%
Alvite, 'V 48-51%
Tritomite, complex silicates i- 2 %
Erdmannite, " " 0-5%
ZIRCONIUM. 51
Contains ZrO2
Polymignite, 5RTiO8-5RZrO3-R(Nb,Ta)2Ofl 29-30%
Arrhenite, complex 3- 4%
Sipylite, V 2-3%
Zirkelite, (Ca,Fe)O • 2(Zr,Ti,Th)O2 52-53%
Baddeleyite, ZrO2 96 • 5%
Extraction. Zirconium salts may be extracted from zircon by the following methods:
(1) The finely powdered mineral is fused with acid potassium fluoride (vid. Experiment 55) (Marignac, Ann. Chim. Phys. [3] LX, 257).
(2) The mineral is fused with potassium bisulphate and the fused mass extracted with dilute boiling sulphuric acid. The basic sulphate (3ZrO-SO3) is left as a residue (Franz, Ber. Dtsch. chem. Ges. n, 58).
(3) The finely powdered mineral is heated with a mix- ture of sodium hydroxide and sodium fluoride, the mass is cooled, pulverized, and extracted with water. The residue, which consists mainly of sodium zirconate, is digested with hydrochloric acid until dissolved. After the solution has been evaporated to a small volume the zirconium oxychloride separates in crystalline form (Bailey, Proc. Royal Soc. XLVI, 74).
The Element. A. Preparation. Elementary zirconium maybe obtained in the amorphous condition (i) by reducing potassium fluozirconate with potassium (Berzelius), and (2) by reducing the oxide with magnesium (Phipson). It may be obtained in crystalline form by heating potassium fluozirconate with aluminum (Troost), and in graphitic form by heating sodium fluozirconate with iron at 850° C.
B. Properties, (i) Zirconium in the amorphous con- dition is a black powder. Heated in the air it burns brightly to the oxide. It oxidizes also when fused with alkali nitrates, carbonates, and chlorates, and is only slightly attacked by acids.
52 THE RARER ELEMENTS.
(2) In crystalline form zirconium has much the ap- pearance of antimony. Heated in the air it oxidizes very slowly. It is not acted upon by fusion with alkali nitrates, carbonates, or chlorates, but is soluble in the acids upon the application of heat. Its specific gravity is 4.15.
Compounds. A. Typical forms. The following are typical compounds of zirconium:
Oxides, ZrO2; ZrO3.
Hydroxide, Zr(OH)4.
Chlorides, ZrCl4; also double salts with KC1 and NaCl.
Oxyhalides, ZrOCl2+3H2O ; ZrOBr2+3H2O ; ZrI(OH)3+3H2(X
Bromide, ZrBr4.
Iodide, ZrI4.
Fluoride, ZrF4.
Sulphite, Zr(S03)2.
Sulphates, Zr(SO4)2 + 4H2O; 3ZrO2-S03.
Selenite, Zr(Se03)2.
Nitrate, Zr(N03)4 + sH2O.
Phosphate, Zr3(PO4)4.
Pyrophosphate, ZrP2O7.
Carbonate, 3ZrO2-CO2 + 8H2O.
Oxalates, Zr(C2O4)2-2Zr(OH)4; Zr(C2O4)2-K2C2O4.H2C2O4-f
8H2O.
Zirconates, Na4ZrO4; Li2ZrO3, etc. Fluozirconate, K2ZrF6.
B. Characteristics. In chemical structure the com- pounds of zirconium bear a strong resemblance to those of thorium, titanium, germanium, and silicon. The oxide, in its behavior as a base toward oxides having more acidic qualities, resembles the oxide of thorium (ThO2). With the' weaker acids, carbonic and oxalic, it shows weaker basic properties in the formation of basic salts. With strong bases it manifests acidic properties, like the oxide of titanium, and forms zirconates (vid. Typical Forms,
ZIRCONIUM. 53
above). The hydroxide of zirconium is insoluble in excess of the alkali hydroxides, the double sulphate with potas- sium is insoluble in a solution of potassium sulphate, and the oxalate is soluble in ammonium oxalate. Solutions of pure zirconium salts are said to give no precipitate with hydrofluoric acid or potassium hydronitride. Turmeric paper, when dipped into a solution of a zirconium salt and dried, is colored orange.
Estimation. Zirconium is usually weighed as the oxide (ZrO2) obtained by ignition of the hydroxide or oxalate.
Separation. Zirconium is a member of the aluminum group, and with the rare earths may be roughly separated from other members of the group by the action of oxalic acid (vid. page 24). For the separation from yttrium, cerium, and thorium see under those elements. The sepa- ration of zirconium from iron and titanium has received a good deal of attention from chemists. Some of the methods that have been suggested follow.
From iron zirconium may be separated (i) by the action of water upon an ethereal solution of the chlorides, — the oxychloride of zirconium being precipitated (Matthews, Jour. Amer. Chem. Soc. xx, 846) ; (2) by the action of gaseous hydrochloric acid and chlorine at a temperature of about 200° C. upon the mixed oxides, — the ferric chloride being volatilized (Havens and Way, Amer. Jour. Sci, [4] vin, 217); (3) by treatment with phenylhydrazine, — the zirconium being precipitated (Allen, Jour. Amer. Chem. Soc. xxv, 426) ; (4) by the action of sulphurous acid on neutral solutions, — the zirconium being precipitated (Baskerville, Jour. Amer. Chem. Soc. xvi, 475).
From titanium zirconium may be separated (i) by boiling a solution containing the two elements with dilute sulphuric and acetic acids, — titanic acid being precipitated free from zirconium (Streit and Franz, J. pr. Chem. cvm, 75 ; Zeitsch. anal. Chem. ix, 388) ; (2) by treating solu-
54 THE RARER ELEMENTS.
tions acid with sulphuric or hydrochloric acid with zinc until the titanium is reduced to the condition of the sesqui- oxide, and then adding potassium sulphate, — the zirconium- potassium sulphate being precipitated (Pisani, Compt. rend. LVII, 298; Chem. News x, 91, 218); (3) by adding ammonium hydroxide to a boiling hydrofluoric acid solu- tion of the salts, — the titanic acid being precipitated (Demarcay, Compt. rend, c, 740; J. B. (1885), 1929).
EXPERIMENTAL WORK ON ZIRCONIUM.
Experiment 55. Extraction of zirconium salts from zircon. Fuse 5 grm. of finely powdered zircon in a platinum or nickel crucible with about 15 grm. of acid potassium fluoride. Pulverize the fused mass and extract with hot water containing a few drops of hydrofluoric acid.* Filter immediately through a rubber funnel into a rubber beaker. As the filtrate cools, potassium fluozirconate crystallizes out. It may be purified by recrystallization.
Experiment 56. Precipitation of zirconium hydroxide, (Zr(OH)4). (a) To a solution of a zirconium salt add potas- sium, sodium, or ammonium hydroxide. Note the insolu- bility in excess. (6) To a solution containing zirconium add sodium thiosulphate in solution and boil.
Experiment 57. Precipitation of zirconium carbonate, (3ZrO2-CO2 + 8H2O). (a) To a solution of a zirconium salt add sodium or potassium carbonate. Note the partial solubility in excess.
(6) Use ammonium carbonate as the precipitant. Note the solvent action of an excess and the precipitation of the hydroxide on boiling.
(c) Try the action of the common acids upon separate portions of zirconium carbonate.
* Glass or porcelain dishes must not be used when hydrofluoric acid is present.
GERMANIUM. 55
&+** * *
Experiment 58. Precipitation of zirconium oxalate, (Zr(C2O4)2-2Zr(OH)4). (a) To a solution of a zirconium salt add a solution of oxalic acid. Note the effect of an excess in the cold and on warming.
(b) Use ammonium oxalate as the precipitant. Note the solvent action of an excess and the reprecipitation by ammonium hydroxide.
Experiment 59. Precipitation of zirconium phosphate, (xZrO2-yP2O5, basic). To a solution of a zirconium salt add sodium phosphate. Orthophosphoric acid precipi- tates the normal phosphate (Zr3(PO4)4).
Experiment 60. Precipitation of zirconium ferrocyanide, (ZrFeC6N6?). To a solution of a zirconium salt add potas- sium ferrocyanide.
Experiment 61. Action of zirconium salts upon turmeric paper. Dip a piece of turmeric paper into a solution of a zirconium salt acidified with hydrochloric acid. Dry on the side of a test-tube or beaker, as in testing for boric acid. Note the yellowish-red color.
Experiment 62. Negative tests of zirconium salts. Note that neither hydrogen sulphide nor potassium fluoride gives a precipitate with zirconium salts. Ammonium sulphide precipitates the hydroxide, not the sulphide.
GERMANIUM, Ge, 72.
Discovery. In 1886 Clemens Winkler announced the presence of a new element in the silver mineral argyrodite, which had been discovered the previous year by Weisbach, in the Himmelsfurst mine near Freiberg (Ber. Dtsch. chem. Ges. xix, 210). According to Winkler 's analysis of argyrodite, the sum of its component parts was seven per cent, less than it should have been; and although he re- peated the analysis several times with great care, the out- come was always the same. This uniformity of result forced
56 THE RARER ELEMENTS.
upon him the conclusion that an unknown element was probably present ; and after much careful and patient work he was successful in isolating it and investigating its prop- erties. On heating the mineral out of contact with the air, he obtained a dark-brown fusible sublimate, which proved to be chiefly two sulphides, that of the new element, named by him Germanium, and the sulphide of mercury.
Occurrence. Germanium is found in combination in a few rare minerals.
Contains Ge
Argyrodite, 4Ag2S-GeS2 ........................ J. 6-7%
Canfieldite, 4Ag2S • (Ge,Sn)S2 ...................... 1.82%
Euxenite, R(NbOJ* • lnSO,), '££^0 ............... traces
Extraction. Germanium salts have been extracted from argyrodite by the following methods:
(1) A Hessian crucible is heated to redness, and small quantities of a mixture consisting of three parts of sodium carbonate, six parts of potassium nitrate, and five parts of the mineral are gradually put in. After being heated for some time the molten mass is poured into an iron dish and allowed to cool. The salt mass may then be removed from the silver, pulverized, and extracted with water. The extract is treated with sulphuric acid and evaporated until all the nitric acid is driven off. The residue is dis- solved in water and allowed to stand until the oxide of germanium separates from the solution.
(2) The mineral is heated to redness in a current of hydrogen, and the sublimate, consisting of a mixture of germanium and mercuric sulphides, is collected. This sublimate is treated with ammonium sulphide, which dis- solves the sulphide of germanium, forming a sulpho salt. After filtration, the solution is acidified with hydrochloric acid, which precipitates the germanium as ftie sulphide.
GERMANIUM. 57
The Element. A. Preparation. Elementary germanium may be obtained (i) by heating the oxide with carbon; (2) by heating the oxide in a current of hydrogen.
B. Properties. Germanium is a grayish-white, metallic element, having a fine luster, and crystallizing in regular octahedra. It volatilizes slightly when heated in hydrogen or nitrogen at about 1350° C.; its melting-point is about 900° C. In the air it does not oxidize at ordinary tem- peratures, but when heated goes over to the oxide GeO2. It is not attacked by dilute hydrochloric acid, is oxidized by nitric acid, and is dissolved by aqua regia. It is dis- solved also by sulphuric acid, with the evolution of sul- phur dioxide. It combines directly with chlorine, bromine, and iodine. Its specific gravity is 5.46.
Compounds. A. Typical forms. The following are typ- ical compounds of germanium:
Oxides GeO Ge02
Hydroxides Ge(OH)2 Ge(OH)4?
Chlorides GeCl2 GeCl4
Oxychloride GeOCl2
Bromide GeBr4
Iodide GeI4
Fluorides GeF2? GeF4? ; K2GeF6; H2GeF6
Sulphides GeS GeS2
Chloroform GeHCl3
Ethyl Ge(C2H5)4
B. Characteristics. The germanium compounds are known in two conditions of oxidation; those of the higher form are the more stable and comprise the larger group. Germanium resembles carbon and silicon in the formation of a chloroform, and tin in the formation of two sulphides which dissolve in ammonium sulphide, giving sulpho salts. The sulphide GeS2 is a white powder slightly soluble in water. The lower sulphide, GeS, when precipitated, is of a
58 THE R4RER ELEMENTS.
reddish -brown color ; when obtained by the reduction of the higher sulphide it is a grayish -black crys" alline substance of metallic luster. This sulphide, also, is slightly soluble in water. The dioxide is a white powder soluble in alkalies, but almost completely insoluble in acids. The tetrachloride is a liquid which fumes in damp air and is decomposed by water.
Estimation. Germanium is usually precipitated as the sulphide, converted by nitric acid into the oxide (GeO2), and weighed as such.
Separation. Germanium may be separated from most of the elements by the formation of a soluble sulpho salt with ammonium sulphide; when the solution is acidified the sulphide is precipitated. Germanium may be separated from arsenic, antimony, and tin as follows: the solution of the sulpho salts is exactly neutralized with sulphuric acid, allowed to stand twelve hours, and filtered; the filtrate is evaporated to a small volume, treated with ammonia and sulphate of ammonium, acidified with sulphuric acid, and saturated with hydrogen sulphide. Germanium sulphide is precipitated (Truchot, Les Terres Rares, 294).
TITANIUM, Ti, 48.1.
Discovery. In the year 1791 McGregor (Crell Annal. (1791) i, 40, 103) discovered a new "metal" in a magnetic sand found in Menachan, Cornwall. This sand he named Mena- chinite, and the newly discovered element Menachite. Four years later Klaproth announced the discovery of a new earth in a rutile which he was engaged in studying (Klapr. Beitr. I, 233). To the metal of this earth he gave the name Tita- nium, in allusion to the Titans. In 1797, however, he found that titanium was identical with menachite (Klapr. Beitr. n, 236).
Occurrence. Titanium is found combined in many
TITANIUM. 59
minerals, but never in considerable quantity in any one locality.
Contains TiO2
Rutile, TiO2 90-100%
Dicksbergite, vid. Rutile 90-100%
Brookite, TiO2 '. 90-100%
Octahedrite, TiO2 90-100%
Pseudobrookite, Fe4(TiO4)3 44- 53%
Perofskite, CaTiO3 58- 59%
llmenite, FeTiO3 3- 59%
Geikielite, MgO -TiO2 67-68%
Senaite, (Fe,Pb)O • 2(Ti,Mn)O2 - 57- 58%
Zirkelite, (Ca,Fe)O-2(Zr,Ti,Th)O2 14- 15%
Knopite, R0-Ti02 54- 59%
Derbylite, 6FeO-5TiO2-Sb2O5 34- 35%
Lewisite, sCaO - 2TiO2 • 3Sb2O5 n- 12%
Mauzeliite, 4(Ca,Pb)O -TiO2 - 2Sb2O5 7- 8%
Titanite, CaTiSiO5 34-42%
Neptunite, R2RTiSi4O12 i?- i8%
Hainite, formula doubtful undetermined
Lamprophyllite, formula doubtful
Keilhauite, complex silicate ' 26- 36%
Schlormenite, 3CaO(Fe,Ti)2O3«3(Si,Ti)O2 12- 22%
Guarinite, CaTiSiO5 33- 34%
Tscheffkinite, complex silicates 16-21%
Astrophyllite, (Na,K)4(Fe,Mn)4Ti(SiO4)4 7- 14%
Johnstrupite, complex silicates 7- 8%
Mosandrite, " 5- 10%
Rinkite, " 13- 14%
Dysanalyte, 6(Ca,Fe)TiO3- (Ca,Fe)Nb2Ofl 40- 59%
Pyrochlore, RNb2Oe-R(Ti,Th)O3, 5- 14%
in in
^schynite, R2Nb4O13-R2(Ti,Th)5O13 21- 22%
Polymignite, sRTiO3-5RZrO3-R(Nb,Ta)2O6 18- 19%
60 THE RARER ELEMENTS.
Contains TiO2
in in Euxenite, R(NbO3)3-R2(TiO3)3-|H20 20-23%
in in Polycrase, R(NbO3)3-2R(TiO3)3-3H2O 25- 29%
Titanium has been found also in sand on the banks of the North Sea, in some mineral waters, in certain varieties of coal, in meteorites, and by means of the spectroscope it has been detected in the atmosphere of the sun. It has been found in the ash of oak, apple, and pear wood, in cow peas, in cotton-seed meal, and in the bones of men and animals. Vid. also Baskerville, Jour. Amer. Chem. Soc. xxi, 1099.
Extraction. Titanium salts may be extracted from rutile by the following methods:
(1) The mineral is fused with three parts of a mixture of sodium and potassium carbonates and the fused mass is extracted with water. The titanium, as a sodium or potassium titanate, remains, together with some tin and iron, in the insoluble residue. This mass is treated with strong hydrochloric acid until dissolved. The solution is then diluted, and the tin is removed by hydrogen sulphide. The sulphide of tin is filtered off, the filtrate is made am- moniacal with ammonium hydroxide and again treated with hydrogen sulphide. The iron is precipitated as the sulphide, and the titanium as the hydroxide. After filtra- tion the precipitate is suspended in water and a current of sulphur dioxide is passed through until the black sul- phide of iron has dissolved, leaving the oxide of titanium.
(2) The mineral is fused with three parts of acid potas- sium fluoride and the fused mass is extracted with hot water and a little hydrofluoric acid. The titanium separates, on cooling, as the potassium fluotitanate (K2TiF6 + H20).
(3) The mineral is fused with six parts of acid potassium sulphate (vid. Experiment 63).
The Element. A. Preparation. Elementary titanium
TITANIUM. 6 1
may be obtained (i) by heating potassium fluotitanate with potassium (Berzelius and Wohler) ; (2) by passing the vapor of the chloride (TiCl4) through a bulb tube con- taining sodium.
B. Properties. As prepared in the laboratory, tita- nium is a dark-gray powder. It does not decompose water at ordinary temperatures and acts on heated water but slightly. When heated in the air it combines with the oxygen, burning brightly to the oxide (TiO2) ; in oxygen the combination is accompanied with brilliant light. Ti- tanium is readily soluble in warm hydrochloric acid, and is attacked by dilute hydrofluoric, nitric, sulphuric, and acetic acids. It combines with chlorine. It combines also with nitrogen, forming nitrides.
Compounds. A. Typical forms. The following are typ- ical compounds of titanium:
Oxides . . . TiO ; (Ti3O4) ; Ti2O3 ; (Tipj ; TiO2 ; (Ti2O5) ; TiO3
Hydroxides Ti(OH)4 Ti(OH)6
Chlorides . . Ti^ TiCl4
Bromide... TiBr4
Iodide TiI4
Fluoride . . . TiF4 Titanofluor-
ides R2TiF6, etc.
Sulphides . . Ti2S3 TiS2
Nitrides. . .. Ti3N4 ; Ti5N6 ; TiN2
Carbide .... TiC
Titanates. . . RTiO3; R2TiO3
Acids (vid. Hydroxides) . . . H2TiO3
B. Characteristics. Although a number of oxides of titanium are known, the dioxide is the form generally found, and the salts of that type are by far the most numer- ous and important. The oxide (TiO2) resembles the oxide of zirconium (ZrO2) in acting as a weak base. It forms
62 THE RARER ELEMENTS.
salts with the strong acids, but does not combine with the
weak acids. It unites with the strong bases to form tita-
ii i
nates, (RTiO3 and R2TiO3). It has less basic and more
acidic properties than the oxide of zirconium. The tet- rachloride is a colorless liquid which fumes in the air. Titanium, in its behavior toward reagents, resembles quite closely both niobium and tantalum, with which it is often found associated (vid. Occurrence).
Estimation. A. Gravimetric. Titanium is usually pre- cipitated as the acid, either by ammonium hydroxide or by boiling a dilute solution acidified with acetic or sulphuric acid; the precipitate is ignited and the element is determined as the oxide (TiO2).
B. Volumetric. Titanium is estimated volumetrically (i) by treating with hydrogen dioxide a definite amount of the titanium solution to be determined and com- paring its color with that of a definite amount of a standard solution of titanium similarly treated (Weller, Ber. Dtsch. chem. Ges. xv, 2592); (2) by reducing the titanium from the dioxide to the sesquioxide condition, by the use of zinc and hydrochloric acid, and then oxidiz- ing it with permanganate (Osborn, Amer. Jour. Sci. [3] xxx, 329).
Separation. The general method for the separation of titanium from the other members of the aluminum group is to boil dilute acidified solutions (vid. Gravimetric Estimation). The titanium precipitate, however, carries down traces of other elements, as aluminum and iron.
From iron titanium may be separated (i) by passing hydrogen sulphide into an alkaline solution to which am- monium tartrate has been added, — the iron sulphide being precipitated (Gooch, Amer. Chem. Jour, vn, 283) ; (2) by treating a mixture of ferrous sulphide and titanic acid with sulphur dioxide (vid. Extraction) ; (3) by boiling a neutral solution with hydrogen dioxide, — metatitanic acid
EXPERIMENTAL WORK ON TITANIUM. 63
being precipitated; (4) by treating a solution of the salts with phenylhydrazine, — titanic acid being precipitated (Allen, Jour. Amer. Chem. Soc. xxv, 421).
From aluminum titanium may be separated by boiling a solution containing them, in the presence of an alkali acetate and of acetic acid to about seven per cent, of the whole solution, — titanium basic acetate being precipitated (Gooch, Amer. Chem. Jour, vn, 283).
From cerium and thorium titanium may be separated by precipitating the double sulphates of those elements with potassium sulphate. Methods for the separation from zirconium have already been given (vid. Zirconium) . From niobium and tantalum titanium may be separated by repeated fusions with acid potassium sulphate and extrac- tions of the melt with water, — the titanium being in soluble form.
EXPERIMENTAL WORK ON TITANIUM.
Experiment 63. Extraction of titanium salts from rutile. (a) Mix 5 grm. of finely powdered mineral with about 30 grm. of acid potassium sulphate and fuse until the mass is free from black particles. Pulverize the fused mass and ex- tract with cold water, stirring frequently until solution is complete. Add ammonium sulphide, filter and wash. Suspend the precipitate, which consists mainly of titanium hydroxide and ferrous sulphide, in water and pass a cur- rent of sulphur dioxide through the liquid until the ferrous sulphide has dissolved, as shown by the disappearance of the dark color. Filter, and wash the titanium hydroxide which remains.
(b) Alternative method. After having dissolved the fused mass in cold water (vid. (a)) add about 20 grm. of tartaric acid to hold up the titanium hydroxide, and make the solution faintly ammoniacal. Pass hydrogen sulphide through until the ferrous sulphide is completely thrown down. Filter, add
64 THE RARER ELEMENTS.
about 10 cm.3 of concentrated sulphuric acid to the filtrate, and evaporate in a porcelain dish under a draught hood until the tartaric acid is thoroughly carbonized. Allow the mass to stand until cool, add water, keeping the liquid cool to prevent the precipitation of the titanium hydroxide, and decant from the carbon residue. Filter the brown liquid through animal charcoal that is free from phos- phates and precipitate the titanium hydroxide with am- monium hydroxide (R. G. Van Name).
Experiment 64. Precipitation of titanium hydroxide, (Ti(OH)4). (a) To a solution containing titanium add sodium, potassium, or ammonium hydroxide. Note the comparative insolubility in excess, especially in ammo- nium hydroxide.
(b) Repeat the experiment, using the alkali carbonates. The precipitate is the same as in (a).
(c) Note the solubility of the freshly precipitated hy- droxide in the common acids.
(d) Ignite a portion of the precipitate and try its solu- bility in acids.
Experiment 65. Precipitation of titanic hydroxide or acid by boiling. (a) Boil a dilute acid solution of titanic hydroxide. Note the precipitation. Filter, and test the filtrate with ammonium hydroxide.
(b) To a solution of titanic acid containing enough free acid to prevent precipitation on boiling, add ammo- nium acetate. Try similarly sodium thiosulphate.
Experiment 66. Color tests of solutions containing titanium, (a) To an acid solution containing titanium add hydrogen dioxide. Note the yellow color (TiO3 in solution).
(b) To a solution containing titanium add a piece of metallic zinc and enough acid to start the action. Note the violet color which develops.
(c) To three portions of dry titanium oxide (Ti02)
NIOBIUM (COLUMBIUM}; TANTALUM. 65
or double fluoride (K2TiF6) add a few drops of strong sulphuric acid. Bring into contact with the first a few particles of tannic acid, with the second a little dry pyro- gallic acid, and with the third some morphia. Note the red color.
Experiment 67. Negative test of titanium compounds. Pass hydrogen sulphide through a solution containing titanium. Note the absence of precipitation.
NIOBIUM (COLUMBIUM), Nb(Cb), 94; TANTALUM, Ta, 183.
Discovery. Hate he tt, while working with some chro- mium minerals in the British Museum in 1801, came across a black mineral very similar to those upon which he was engaged (Phil. Trans. Roy. Soc. (1802), 49). He obtained permission to examine it and found it to consist almost wholly of iron and an earth which did not conform to any known test. He described it as "a white, tasteless earth, insoluble in hot and cold water, acid to litmus, infusible before the blowpipe, and not dissolved by borax. ' ' The only acid which dissolved it was sulphuric. Since the mineral was of American origin, coming from Con- necticut, the discoverer named it Columbite, and the element Columbium.
About a year later Ekeberg (Crell Annal. (1803) i, 3), while investigating a mineral from Kimito, Finland, which closely resembled columbite, discovered a "metal" which resembled tin, tungsten, and titanium. It proved to be none of these, but in fact a new element. He named it Tantalum, ' ' because even when in the midst of acid it was unable to take the liquid to itself. ' ' Indeed, insolu- bility in acid seemed to be the chief characteristic of the new substance.
The apparent similarity of columbium and tantalum suggested that they might be identical, and in order to
66 THE R4RER ELEMENTS.
solve this problem Wollaston (Phil. Trans. Roy. Soa xcix, 246) in 1809 began to work on tantalite and a speci- men of the same columbite that Hatchett had examined. He found that the freshly precipitated acids were both soluble in concentrated mineral acids; if they were dried it was necessary to fuse them both with caustic alkalies before they could be dissolved. Both were held up if ammonium hydroxide was added in the presence of citric, tartaric, or oxalic acid. Having found practically the same reactions with both acids, he concluded that the elementary substances were the same. The specific gravity of tantalite, however, was 7.95, and that of columbite 5.91. This he explained by suggesting different conditions of oxidation or different states of molecular structure. These con- clusions were accepted, and for many years the element was called indifferently tantalum and columbium.
In 1844 Rose began to investigate the same subject. His work on the columbites of Bodenmais and Finland led him to the belief that there were two distinct acids in the columbite from Bodenmais, one similar to that in tantalite, the other containing a new element, to which he gave the name Niobium, from Niobe, daughter of Tan- talus. Though niobium proved to be Hatchett 's colum- bium, Rose's name for the element has been the one more generally adopted.
Occurrence. Niobium and tantalum are found, each in combination, in various rare minerals. They usually, though not invariably, occur together.
Corttains Nb205
Pyrochlore, RNb2O6-R(Ti,Th)O3 47~58%
Koppite, R2Nb2O7 • fNaF. . . , 61-62 %
Hatchettolite,
2R(Nb/ra)aOfl.Ra(Nb,Ta)207 63-67%*
*Nb205+Ta206-
NIOBIUM (COLUMBIUM); TANTALUM. 67
Contains Nb205 Ta205
Microlite, Ca2Ta2O7 7-8% 68-69%
Fergusonite, (Y,Er,Ce)(Nb,Ta)O4 14-46% 4~43%
in Sipylite, RNbO4 47~48% i- 2%
Columbite, (Fe,Mn)(Nb,Ta)2O6. . 26-77% i~77%
Tantalite, FeTa2O6 3-40% 42-84%
Skogbolite, '-1 , 3-40% 42-84%
Tapiolite, Fe(Nb,Ta)2O6 11-12% 73~74%
Mossite, Fe(Nb,Ta)2O6. . 83%*
'2 II III
Yttrotantalite, RR2(Ta,Nb)4O15. 12-13% 46-47%
in ii Samarskite, R2R3(Nb,Ta)6O21 41-56% 14-18%
Stibiotantalite, Sb2O3(Ta',Nb)2O5? 7 - 5 % ji%
o
Annerodite, complex 48-49%
Hielmite, complex. . . 4-16% 55-72%
in in
^schynite, R,Nb4Olt.R,(Ti,Th)Ai 32-33% 21-22%
Polymignite,
5RTiO3-5RZr03.R(Nb,Ta)2O6 11-12% i- 2%
in in
Euxenite, R(NbO3)3-R2(TiO3)3-|H20 18-35%
in in
Polycrase, R(NbO3)3-2R2(TiO3)3.3H2O. . . 19-25% o- 4%
Wohlerite, i2R(Si,Zr)O3-RNb2O6 12-14%
Lavenite, R(Si,Zr)O3 • Zr(SiO3)2 • RTa2O6. . o- 5 %*
Dysanalyte, 6RTiO3-RNb2O6 0-23% o- 5%
Eucolite, complex, silicates 2- 4%*
Melanocerite, complex silicates 3- 4%
Tritomite, complex silicates I- 3%
Cassiterite (ainalite), SnO2 o- 9%
Extraction. Salts of niobium and tantalum may be extracted from columbite or tantalite by either of the fol- lowing methods:
* Nb205+Ta205.
68 THE RARER ELEMENTS.
(1) The mineral is fused with six parts of potassium bisulphate, the fused mass is pulverized and treated with hot water and dilute hydrochloric acid. The residue is then digested with ammonium sulphide to remove tin, tung- sten, etc., and again warmed with dilute hydrochloric acid. After this treatment it is washed thoroughly with water and dissolved in hydrofluoric acid. Filtration is followed by the addition of potassium carbonate to the clear solu- tion until a precipitate begins to form. The potassium and tantalum double fluoride separates first in needle- like crystals, after which the niobium oxyfluoride crys- tallizes in plates.
(2) The mineral is fused with three parts of acid potas- sium fluoride (vid. Experiment 68).
The Elements. I. NIOBIUM. -A. Preparation. The ele- ment niobium may be obtained by reducing the chloride with hydrogen at a high temperature (Bloomstrand).
B. Properties. Niobium is a metallic element of steel-gray color and brilliant luster. Heated in the air it ignites; heated in chlorine it forms the chloride (NbCl5). It is very slightly soluble in hydrochloric acid, nitric acid, and aqua regia, but dissolves in concentrated sulphuric acid upon the application of heat. Its specific gravity is 7.06.
II. TANTALUM. A. Preparation. Elementary tanta- lum may be obtained by heating the potassium and tantalum fluoride (K2TaF7) with potassium and extract- ing the potassium fluoride with water.
B. Properties. Tantalum in the elementary condition is a black substance with a metallic luster. Like niobium it ignites when heated in the air and forms the chloride, (TaCl5), when heated in chlorine. It is insoluble in hydro- chloric, nitric, and sulphuric acids, and in aqua regia, but dissolves in hydrofluoric acid. Its specific gravity is 10.78.
Compounds. A. Typical forms. The following are typ- ical compounds of niobium and tantalum:
NIOBIUM (COLUMBIUM); TANTALUM. 69
Oxides .......... Nb,O2
Nb2O4 Ta2O4
Nb206 Ta20,
Chlorides ........ NbCl3
NbCl5 Tad.
Oxychloride ..... NbOCl,
Bromides ....... NbBr5 , TaBr5
Oxybromide. . . . NbOBr,
Fluorides ....... NbF6 TaF8
Oxyfluoride ..... NbOF3
Fluotantalates . . K,TaF7
Na2TaF7 (NH4)2TaF7 Double fluorides .
Sulphide ........ Ta2S4
Oxysulphide. . . . Nb2OS3
Nitride ......... TasN,
Niobates ........ K8Nb6O19 + i6H2O
K6Nb4013 + i3H20
2K2Nb4Ou
K4Nb2O7 +
NalflNb14043
Na2Nb2O6, etc.
Tantalates ...... Of types R8Ta6O19 and RTaO3,
with Na, K, NH4, Ba, and Mg.
B. Characteristics. The compounds of niobium closely resemble those of tantalum, both in chemical form and in behavior toward reagents. The two elements are closely associated in minerals (vid. Occurrence) . The lower oxides of niobium are dark powders which oxidize when heated. The dioxide is soluble in hydrochloric acid, while the tetrox- ide is not attacked by acids. The pentoxide is a yellowish- white amorphous powder somewhat soluble in concen- trated sulphuric acid before ignition, but insoluble after.
70 THE RARER ELEMENTS.
Niobium pentachloride is a yellow crystalline substance which tends to form the oxychloride in the presence of water, and is reduced to the trichloride when its vapor is passed through a red-hot tube. The fluoride is formed by the action of hydrofluoric acid upon the pentoxide.
Tantalum tetroxide is a very hard, dark-gray, porous mass which is not attacked by acids. When heated it goes over to the higher oxide. The pentoxide of tanta- lum is a white powder which is somewhat soluble in acids. The chloride and fluoride of tantalum are formed similarly to the corresponding salts of niobium and resemble them in general behavior. Niobates and tantalates are obtained by fusing the oxides with caustic alkalies; these salts are soluble. The tantalum compounds give no color test with morphia, tannic acid, or pyrogallic acid.
Estimation. A. Gravimetric. Niobium and tantalum are ordinarily weighed as the oxides Nb2O5 and Ta2O5, obtained from ignition of the acids.
B. Volumetric. Niobium may be estimated volume t- rically by reduction from the condition of the pentoxide to that of the trioxide by means of zinc and hydrochloric acid in a current of carbon dioxide, and oxidation with permanganate (Osborn, Amer. Jour. Sci. [3] xxx, 329).
Separation. The method usually employed for the separation of niobium and tantalum from the elements with which they are generally associated — namely, tita- nium, zirconium, and thorium — is that of fusion with acid potassium sulphate (vid. Titanium). From tin and tung- sten they may be separated by ammonium sulphide.
The separation of niobium from tantalum is one of the most difficult of analytical problems. Marignac's method (Ann. Chim. Phys. [4] viu, i), based upon the
difference in solubility* between the tantalum-potassium
— 1
*K2TaF7 is soluble in 151-157 parts of cold water. 2KF • NbOF3+ H2O is soluble in 12-13 parts of cold water.
EXPERIMENTAL WORK ON NIOBIUM AND TANTALUM. 7 1
fluoride (K2TaF7) and the niobium-potassium oxy fluoride (2KF-NbOF3 + H2O), is the most satisfactory known.
EXPERIMENTAL WORK ON NIOBIUM AND TANTALUM.
Experiment 68. Extraction of niobium and tantalum salts from cohtmbite or tantalite. Mix 5 grm. of the finely ground mineral with 15 grm. of acid potassium fluoride and fuse thoroughly. Pulverize the fused mass and extract with boiling water containing a little hydrofluoric acid. Evaporate to about 200 cm.3 and allow the liquid to stand. The potassium and tantalum fluoride separates first in needle-like form; the niobium and potassium oxyfluoride crystallizes in plates on concentration of the solution. The salts of the two elements should be purified as far as possible by fractional crystallizations.
Experiment 69. Preparation of niobic and tantalic oxides (acids), (Nb2O5; Ta2O5). (a) Evaporate a solution of potassium and niobium oxyfluoride to dryness, add strong sulphuric acid, and heat until all the hydrofluoric acid is expelled and a solution is obtained. Cool the solution, dilute with water, and boil. Niobic acid, (Nb2O5), is pre- cipitated. Filter, and test the filtrate with ammonium hydroxide.
(6) Repeat the experiment, using a solution of potas- sium and tantalum fluoride instead of the niobium salt.
(c) Test the action of alkali hydroxides or carbonates in excess upon solutions of niobium and tantalum obtained in (a) and (b).
Experiment 70. Action of fusion with sodium or potas- sium hydroxide upon niobic and tantalic acids, (a) Melt a gram of sodium or potassium hydroxide in a hard glass tube, add a small quantity of dry niobic acid, and heat again. Note that the fused mass is soluble in water.
72 THE RARER ELEMENTS.
(b) Repeat the experiment, using dry tantalic acid instead of niobic.
(c) Acidify portions of the solutions obtained in (a) and (b).
Experiment 71. Color tests for niobium, (a) Treat separate portions of dry niobic oxide (or acid) with tannic acid, pyrogallic acid, and morphia, as in Experiment 66 (c). Note the brown color.
(6) Repeat the experiment, using tantalic oxide instead of niobic. Note the absence of color.
(c) Try the action of metallic zinc upon an acid solu- tion containing niobium.
Experiment 72. Negative tests of niobium and tantalum. Note that hydrogen sulphide gives no precipitate, and that hydrogen peroxide gives no yellow color with acid solutions containing niobium or tantalum.
INDIUM, In, 114.
Discovery. Indium was discovered by Reich and Richter in 1863, in the course of an examination of two ores consisting mainly of the sulphides of arsenic, zinc, and lead (J. pr. Chem. LXXXIX, 441). These ores had been freed from the greater part of their arsenic and sulphur by roasting, and the residue had been evaporated to dry- ness with hydrochloric acid and distilled. The crude chloride of zinc thus obtained was examined with the spectroscope for thallium, since the presence of that element had been indicated in similar ores from the Freiberg mines. Instead of the thallium line, however, appeared one of indigo blue never before observed. The color suggested the name Indium for the unknown element present.
Occurrence. Indium occurs in very small amounts, combined with sulphur, in many zinc-blendes. It has been found in zinc-blende from Freiberg and Breitenbrun in
INDIUM. 73
Saxony, and from Schonfeld in Bohemia ; in christophite, a variety of zinc-blende; in zinc prepared from these ores; and in the flue-dust from ovens used for roasting zinc ores. It has also been found in wolframite from Zinnwald. The proportion of indium in the minerals named varies from one tenth of one per cent, to mere traces. Lockyer de- tected it in the atmosphere of the sun. Hartley and Ra- mage (Jour. London Chem. Soc. (1897), 533, 547) have dis- covered it spectroscopically in many iron ores, — notably siderites, — in some manganese ores, in zinc-blendes, in five tin ores examined, and in many pyrites.
Extraction. Indium salts may be obtained as follows from zinc that has been extracted from indium-bearing blendes. The crude metal is nearly dissolved in hydro- chloric or nitric acid, and the solution is allowed to stand twenty-four hours with the undissolved metal. A spongy mass, consisting of the indium together with lead, copper, cadmium, tin, arsenic, and iron, collects upon the residual zinc. This mass is washed with water containing some sulphuric acid ; it is then dissolved in nitric acid and evapo- rated with sulphuric acid until all the nitric acid is removed. By this process the lead is precipitated, and it may be removed by filtration. The solution that remains is treated with ammonium hydroxide in excess, and the hydroxides of iron and indium are filtered off and dissolved in a small amount of hydrochloric acid. This solution is treated with an excess of acid sodium sulphite and boiled. In- dium is precipitated as the basic sulphite (In2(SO3)3 • In2(OH)6 + 5H20).
The Element. A. Preparation. Elementary indium may be obtained (i) by heating the oxide with carbon or in a current of hydrogen; (2) by heating the oxide with sodium under a layer of dry sodium chloride ; (3) by treating the salts with zinc.
B. Properties. Indium is a soft white metal, less vola-
74 THE RARER ELEMENTS.
tile than cadmium and zinc. It melts at 174° C. At ordinary temperatures it is very stable in the air, but when heated it ignites and burns with a violet flame to the oxide. It does not decompose boiling water. It dissolves easily in hydrochloric, nitric, and sulphuric acids. Its specific gravity is given at from 7.1 to 7.4.
Compounds. A. Typical forms. The following com- pounds of indium are known:
Oxides ............. InO In2O3
Hydroxide .......... In(OH),
Chlorides ........... InCl InCl2 InCl3
Indium - hydrochloric
acid ............. H3InCl6
Bromide ........... InBr3
Iodide ............ . InI3
Nitrate ........... . In2(NO3)6 + 9H2O
Sulphate .......... . In2(SO4)3
Double sulphates ____ In2(SO4)3 - K2SO4 + 24H2O ;
In2(S04)3.(NH4)2S04 +
Sulphite ........... ;:- In2(S03)3 - In2(OH)6 + 5H2O
Sulphide .......... '. In2S3
Sulpho salts ......... K2In2S4 ; Na2In2S4
B. Characteristics. Indium resembles aluminum in forming alums with potassium and ammonium sulphates, and in having a hydroxide soluble in excess of potassium or sodium hydroxide. It resembles zinc in forming a sulphide with hydrogen sulphide, but in the case of indium this salt is yellow. Indium monoxide is a dark powder slowly soluble in dilute acids. The sesquioxide is a yellow- ish-white powder easily soluble in warm acid. The di- chloride is formed directly by the union of chlorine with the metal, and is a white, crystalline mass. In water it sepa- rates into the trichloride and the metal. By fusion of
GALLIUM 75
the dichloride with elementary indium the monochloride is formed, — a reddish-black, crystalline substance. The trichloride is formed also by the action of chlorine in excess upon the metal ; it is white like the dichloride and dissolves in water with the evolution of heat. Solutions of indium salts color the flame violet and give a characteristic flame spectrum.
Estimation. Indium is generally determined as the oxide, (In2O3), obtained by ignition of the hydroxide, or as the sulphide, (In^g), obtained by precipitation with hydro- gen sulphide in the presence of sodium acetate.
Separation. The separation of this very rare element from those elements with which it is usually associated is treated under Extraction.
GALLIUM, Ga, 70.
Discovery. In 1875 Lecoq de Boisbaudran, who had done much work with spectrum analysis, notified the Academic des Sciences of his discovery of a new element in a zinc-blende from the mine of Pierrefitte in the Pyre- nees, and proposed for it the name Gallium (Compt. rend. LXXXI, 493; Chem. News xxxn, 159). The individu- ality of the new body was distinctly indicated by the spectroscope, but so small was the amount of it in the possession of the discoverer that few of its reactions were determined. Among the properties which he described, however, were the following: the oxide, or perhaps a sub- salt, was thrown down by metallic zinc in a solution con- taining chlorides and sulphates; in a mixture containing an excess of zinc chloride the new body was the first to be precipitated by ammonia; in the presence of zinc it was concentrated in the first sulphides deposited; the spark spectrum of the concentrated chloride showed two violet lines, one of them of considerable brilliance.
76 THE RARER ELEMENTS.
Occurrence. Gallium is found combined, in very small amounts, in certain minerals, chiefly zinc-blendes from Bensberg on the Rhine, Pierrefitte, and other localities. It has been detected in some American zinc-blendes (Chem. Ztg. (1880), 443). The Bensberg sphalerite, one of the richest sources, contains 0.016 grm. per kilo.
Hartley and Ramage obtained the following interesting results by means of the spectroscope (Jour. London Chem. Soc. (1897), 533, 547) : the presence of gallium was indicated in thirty -five out of ninety -one iron ores examined; in all the magnetites, seven in number; in all the aluminum ores, fifteen in number, mostly kaolin and bauxite; in four out of twelve manganese ores; and in twelve out of fourteen zinc-blendes.
Extraction. Salts of gallium are obtained by the fol- lowing process : The mineral is dissolved in aqua regia and the excess of acid expelled by boiling. When the solution is cold, pure zinc is added, which precipitates the antimony, arsenic, bismuth, copper, cadmium, gold, lead, mercury, silver, tin, selenium, tellurium, and indium. These are filtered off while there is still some evolution of hydrogen, and the filtrate is boiled from six to twenty-four hours with metallic zinc. Gallium is precipitated as a basic salt, together with salts of aluminum, iron, zinc, etc. To obtain the gallium salt in a more nearly pure condition the precipitate is dissolved in hydrochloric acid, the solu- tion is treated with hydrogen sulphide, and after filtra- tion and the removal of the excess of hydrogen sulphide by boiling, sodium carbonate is added in small portions. The gallium salt is the first to be precipitated, and the pre- cipitates are collected as long as they show the gallium lines in the spark spectrum. These precipitates are dis- solved in sulphuric acid and the solution is diluted largely with water and boiled. The basic sulphate of gallium which is thus thrown down is dissolved in sulphuric acid,
GALLIUM. 77
and potassium hydroxide is added in excess. Iron if present is removed at this point by filtration and the gallium oxide is then precipitated from the filtrate by carbon dioxide.
The Element. A. Preparation. Gallium in the elemen- tary condition has been obtained by subjecting an alkaline solution of the oxide to electrolysis.
B. Properties. A gray, lustrous metal, showing green- ish-blue lights on reflecting surfaces, gallium is malleable and fairly hard. Its fusing point, 30.15° C., is so low that it melts readily from the warmth of the hand. In water, and in air at ordinary temperatures, it is unchanged ; when heated in air or oxygen it is oxidized only superfi- cially. It combines rapidly with chlorine, more slowly with bromine, and not at all with iodine unless heat is applied. Gallium is soluble in hydrochloric and warm nitric acids, and somewhat soluble in potash and ammonia solutions. It alloys easily with aluminum, and these alloys decompose cold water rapidly. Its specific gravity is 6.
Compounds. A. Typical forms. The following com- pounds of gallium are known :
Oxides GaO? Ga2O3
Hydroxide Ga(OH)3?
Chlorides GaCl2 GaCl3
Bromide GaBr3
Iodide GaI3
Nitrate Ga,(NO,)«
Sulphate Ga2(SO4)3
Double sulphate Ga2(SO4)3 • (NH4)2SO4 + 24H2O
B. Characteristics. The compounds of gallium resem- ble those of aluminum and indium in forming alums and in having a hydroxide soluble in excess of sodium or potassium hydroxide. The salts are colorless, and in dilute solutions tend, on being heated, to become basic
78 THE RARER ELEMENTS.
and separate from the solution. The oxide (Ga2O3) is in- soluble in acids and alkalies after ignition.
Estimation. Gallium is usually weighed as the oxide (Ga203).
Separation.* Vid. Extraction.
THALLIUM, Tl, 204.1.
Discovery. Some years previous to 1861 Crookes had been engaged in the extraction of selenium from a selen- iferous deposit which he had obtained from the sulphuric- acid manufactory at Tilkerode in the Hartz Mountains. Some residues, left after the purification of the selenium, and supposed to contain tellurium, were set aside and not examined until 1861, when, needing tellurium, Crookes vainly tried to isolate it by various chemical methods. At length he resorted to spectrum analysis and tested some of the residue in the flame. The spectrum of selen- ium appeared, and as it was fading, and he was looking for evidence of tellurium, a new bright-green line flashed into view. The element whose presence was thus indicated received the name Thallium, from the Greek 6ct\Xost or the Latin thallus, a budding twig (Chem. News in, 194).
About the same time Lamy announced the discovery of the same element (Ann. Chim. Phys. [3] LXVII, 385), but after much discussion and the presentation of much evidence on both sides it was declared that Crookes had the priority of discovery.
Occurrence. Thallium occurs in certain very rare minerals :
Crookesite, (Cu,Tl,Ag)2Se, contains 16-19% Tl Lorandite, TlAsS2, " 59-60% Tl
* For a detailed study of the separation of gallium, see many articles by Lecoq de Boisbaudran, Compt. rend, xciv-xcvm.
THALLIUM. 79
It is found also in very small quantities in berzelianite, (Cu2Se) ; in some zinc-blendes and copper pyrites ; in iron pyrites from Theux, Namur, Philippe ville, Alais, and Nantes ; in lepidolite from Mahren; and in mica from Zinnwald. It has been detected, together with caesium, rubidium, and potassium, in the mineral waters of Nauheim and Orb. Its presence in the flue-dust from some iron furnaces and sulphuric-acid works, as well as in some crude sulphuric and hydrochloric acids, may be traced to its presence in the pyrites used.
Extraction. Thallium salts may be extracted by the following methods:
(1) From minerals. The finely powdered mineral is dis- solved in aqua regia. The solution is evaporated with sulphuric acid until the free acid has been removed ; it is then diluted abundantly with water, neutralized with sodium carbonate, and treated with potassium cyanide in excess. This precipitates the bismuth and lead, which are filtered off. The filtrate is treated with hydrogen sulphide, which precipitates the cadmium, mercury, and thallium as the sulphides. Very dilute sulphuric acid dissolves the thallium sulphide, leaving the cadmium and mercury sulphides undissolved (Crookes).
(2) From flue-dust. The material is treated with an equal weight of boiling water in a large wooden tub, and is allowed to stand twenty-four hours. The liquid is si- phoned off and is precipitated with hydrochloric acid.* The crude chloride thus obtained is treated with an equal weight of sulphuric acid, and heated to expel the hydro- chloric acid and the greater part of the excess of sulphuric. The sulphate obtained is dissolved in water, the solution is neutralized with chalk and filtered. By the addition of hydrochloric acid to the filtrate, nearly pure thallous chloride is precipitated (Chem. News vm, 159).
* Three tons of dust gave sixty-eight pounds of crude thallous chloride.
8o
THE RARER ELEMENTS.
The Element. A. Preparation. The element thallium may be obtained (i) by fusing a mixture of thallous chloride and sodium carbonate with potassium cyanide; (2) by submitting the carbonate or the sulphate to electrolysis; (3) by heating the oxalate; and (4) by precipitating with zinc from an alkaline solution of a thallous salt.
B. Properties. Metallic thallium is in color whitish to blue gray, with the luster of lead. It is soft and malle- able and melts at 285° C. It oxidizes readily at high temperatures, but is not acted upon by water free from air. It is soluble in dilute nitric and sulphuric acids. It is a poor conductor of electricity. The specific gravity of thallium is n.88.
Compounds. A. Typical forms. The following are typ- ical compounds of thallium:
Oxides .......... T12O T12OS
Hydroxides ...... T1OH T1(OH)3
Carbonate ....... T12COS
Chlorides ........ T1C1 T1C13+ H2O
Double chlorides . . T1C1 • HgCl2 ; 3T1C1 • Fed, ; T1C1, - 3KC1+ 2H2O ; etc.
TlCl-AuCl,; etc.
Chlorate ......... T1C1OS
Perchlorate ...... T1C1O4
Bromides ........ TIBr TlBr,
Double bromides . . TlBr3 • KBr+ 2H2O ;
TlBr8-3TlBr
Bromate ......... TIBrO,
Iodides .......... Til Til,
Double iodides ---- Til - KI T1I3 • NH4I
lodates .......... T1IOS T1(IO3)8
Periodate ........ 3T12O3 - I2O7+ 3oH2O
Thiosulphate ..... TlzS^
Sulphides ........ T1,S T12S3
Sulphite ......... TljSO,
Sulphates ........ TljSO, ; T1HSO4 Tl^SOJ,
Double sulphates . . with MgSO4, ZnSO4, CuSO4, etc.
Alums ........... T12S04- A12(S04),+ 24H2O;
Tl2S(VFe2(S04)3+24H20
Nitrates .......... T1NOS T1(NO3)3+ 4H2O
Phosphates ....... T13PO4; T14P2O7; T1PO, T1PO4+ 2H2O
THALLIUM. 8 1
Arseniates Tl8AsO4 Tl AsO4+ 2H2O
Cyanides T1CN T1(CN)3-T1CN
Sulphocyanide T1SCN
Ferrocyanide Tl4Fe(CN)8-f- 2H,O
Silicofluoride TljSiF8
Chromates Tl2CrO4; Tl2Cr2OT
Chloroplatinate . . . Tl2PtCl8 •
Molybdate Tl2MoO4
Tungstate T12WO4
Vanadates T13VO4; T14V2O7; T1VO3
B. Characteristics. Thallium compounds are known in two conditions of oxidation, the thallous, (T12O), and the thallic, (T12O3) . The lower condition is the more stable ; consequently the thallous compounds are the more numer- ous and the better known. When the metal is allowed to oxidize in the air it forms the thallous oxide, but when it is melted in an atmosphere of oxygen, thallic oxide is ob- tained. Thallic chloride, bromide, and iodide may be formed by treating the corresponding thallous salts with an excess of chlorine, bromine, and iodine, respectively. In general, the thallous salts may be oxidized to the thallic form by strong oxidizing agents, such as potassium per- manganate, lead dioxide, barium dioxide, etc. Thallium in the lower condition resembles the alkalies potassium, caesium, and rubidium in having a soluble hydroxide, car- bonate, and sulphate, and an insoluble chloroplatinate ; also in forming alums. It resembles lead in forming an insoluble sulphide and chromate, and in having halogen salts soluble in hot water. The thallous salts are color- less when the base is combined with a colorless acid. The sulphide is brownish black. The thallic salts are in general unstable, and on being heated with water tend to precipitate the oxide (T12O3-H20). They may be easily reduced to the lower condition by the action of reducing agents. They may be formed by the careful treatment of thallic oxide with acids, as well as by the action of strong oxidizing agents upon the thallous salts. Solutions of thallium
82 THE RARER ELEMENTS.
salts in either condition of oxidation give to the flame a characteristic green color.
Estimation.* A. Gravimetric. Thallium is generally weighed in the thallous condition (i) as the chloroplati- nate, (Tl2PtCl6), after precipitation by chloroplatinic acid (Crookes, Select Methods, Second Edition, 380) ; (2) as the iodide (Til), after precipitation by potassium iodide (Werther, Zeitsch. anal. Chem. in, i, and J. B. (1864), 712; Long, Zeitsch. anal. Chem. xxx, 342) ; (3) as the chro- mate (Tl2CrO4), after precipitation in alkaline solution by potassium chromate (Browning and Hutchins, Amer. Jour. Sci. [4] vin, 460); (4) as the sulphate (T12SO4), after evaporation of appropriate salts with sulphuric acid in ex- cess and ignition at low red heat, or as the acid sulphate, (T1HSO4), obtained by substituting for ignition heating at 220°-240°C. (Browning, Amer. Jour. Sci. [4] ix, 137).
B. Volumetric. Thallium is estimated volumetric- ally (i) by the oxidation of thallous salts with perman- ganate (Crookes, Select Methods, Second Edition, 381); (2) by the action of potassium iodide upon thallic salts, as shown in the following equation (Thomas, Compt. rend. cxxxiv, 655): T1C13 + 3KI=T1I + 3KC13 + I2.
Separation.! In the more stable thallous condition, to which thallic salts may readily be reduced, thallium may be separated as follows: from the metals which give precipitates with hydrogen sulphide in acid (but not acetic) solution, by hydrogen sulphide; from elements which form insoluble hydroxides' with the alkali hydroxides, by these reagents; and from the alkalies and alkali earths, by ammonium sulphide.
* See also Hebberling, Liebig Annal. cxxxv, 207 ; Phipson, Compt. rend. LXXVIII, 563; Neumann, Liebig Annal. ccxuv, 349; Feit, Zeitsch. anal. Chem. xxvin, 314; Carnot, Compt. rend, cix, 177; Sponholz, Zeitsch. anal. Chem. xxxi, 519; Thomas, Compt. rend, cxxx, 1316; Marshall, Jour. Soc. Chem. Ind. xix, 994.
t See Crookes, Select Methods, Second Edition, 382-386.
EXPERIMENTAL WORK ON THALLIUM. 83
EXPERIMENTAL WORK ON THALLIUM.
Experiment 73. Extraction of thallium salts from flue- dust. The method described under Extraction may be followed.
Experiment 74. Precipitation of thallous chloride, bro- mide, and iodide (T1C1; TIBr; Til), (a) To a solution of a thallous salt add hydrochloric acid or a chloride in solu- tion. Note the solvent action of boiling water. Try the effect of cooling the hot solution.
(b) Repeat the experiment, using potassium bromide as the precipitant.
(c) Try similarly potassium iodide.
Experiment 75. Precipitation of thallium chloroplati- nate (Tl2PtCl6). To a solution of a thallous salt add a few drops of a solution of chloroplatinic acid.
Experiment 76. Precipitation of thallous chr ornate (Tl2CrO4). To a solution of a thallous salt add some potas- sium chromate in solution. Try the action of acids upon the precipitate.
Experiment 77. Precipitation of thallous sulphide (T12S). (a) Through a solution of a thallous salt acidified with dilute sulphuric acid pass hydrogen sulphide. Note the absence of precipitation. Divide the solution, and to one part add ammonium acetate and to the other ammonium hydroxide.
(b) Try the action of ammonium sulphide upon a thal- lous salt in solution.
Experiment 78. Oxidation of thallous salts, (a) To a solution of a thallous salt acidified with sulphuric acid add gradually a little potassium permanganate. Note the disappearance of the color of the permanganate.
(b) To a solution of a thallous salt add bromine water until the color of the bromine ceases to fade. To one portion add a few drops of a solution of a chloride or bro-
**4 THE RARER ELEMENTS.
mide. Note the absence of precipitation. To another portion add sodium or potassium hydroxide. Note the precipitation of brown thallic hydroxide, (T12O3-H2O).
Experiment 79. Reduction of a thallic salt. To a solution of a thallic salt formed, for example, as in Experiment 78 (b) add stannous chloride. Note the precipitation of thallous chloride, (T1C1).
Experiment So. Flame and spectroscopic tests for thal- lium salts, (a)' Dip the end of a platinum wire into a solution of a thallium salt and hold it in the flame of a Bunsen burner. Note the green color.
(b) Examine spectroscopically the flame colored by a solution of a thallium salt. Observe the green line.
Experiment 81. Negative tests of thallous salts. Note that sulphuric acid and the alkali hydroxides and car- bonates give no precipitate with solutions of thallous salts.
VANADIUM, V, 51.2.
Discovery. As early as 1801 Del Rio announced the discovery of a new metal in a lead ore from Zimapan, Mexico. He named it Erythronium (epvQpos, red), be- cause its salts became red when heated with acids (Annal. der Phys. u. Chem. LXXI, 7). Fourteen years later Collet Descotils examined the supposed metal and pro- nounced it an impure oxide of chromium, — a conclusion that Del Rio himself came to accept (Ann. de Chim. LIII, 268).
In 1830 Sef strom found an unknown metal in an iron ore from Taberg, Sweden. He proposed for it the name Vanadium, from Vanadis, the Scandinavian goddess more commonly known as Freia (Amer. Jour. Sci. [i] xx, 386). Almost immediately Wohler showed the identity of vana- dium with the metal described by Del Rio (Pogg. Annal. xxi, 49).
VANADIUM. 85
Occurrence. Vanadium is found quite widely distrib- uted, but always in combination, and in very small quan- tities:
Contains V205.
Vanadinite, (PbCl)Pb4(VO4)3 8-21 %
Descloizite, (Pb,Zn)2(OH)VO4 20-22%
Cuprodescloizite, (Pb,Zn,Cu)2(OH)VO4 17-22%
Calciovolborthite, (Cu,Ca)2(OH)VO4 .'.... 37~39%
Carnotite, K2O-2U2O3-V2O5-3H20 19-20%
Brackebuschite, formula doubtful 24-25%
Psittacinite, formula doubtful 17-26%
Volborthite, 14-15%
Pucherite, BiVO4 22-27%
Roscoelite, silicate, formula doubtful 21-29%
Ardennite, " " " traces - 9%
Vanadium has been detected also in some copper, lead, and iron ores, in certain clays and basalts, and sometimes in soda ash and phosphate of soda.
Extraction. Vanadium salts may be extracted from mineral sources by the following methods:
(1) The mineral is fused with potassium nitrate, and . the potassium vanadate thus formed is extracted with water.
By the addition of a soluble lead or barium salt to the solution the lead or barium vanadate is precipitated. This insoluble vanadate is decomposed by means of sulphuric acid, and the barium or lead sulphate is filtered off. By saturation of the filtrate with ammonium chloride the ammonium vanadate is precipitated.
(2) The finely ground mineral is decomposed by nitric acid (vid. Experiment 82).
The Element. A. Preparation. Elementary vanadium may be prepared by long heating of the dichloride in a cur- rent of hydrogen.
86 THE RARER ELEMENTS.
B. Properties. Vanadium is a non-magnetic, light- gray powder, somewhat crystalline in appearance. It oxidizes slowly in the air at ordinary temperatures, but more rapidly when heated, going through various degrees of oxidation and showing a characteristic color for each oxide,— brown (V2O), gray (V2O2), black (V2O3), blue (V2O4), and red (V2O5). Upon the application of heat vanadium unites with chlorine, forming the chloride VC14; at a red heat it combines with nitrogen, giving the nitride VN. It is insoluble in hydrochloric and dilute sulphuric acids, and soluble in nitric, hydrofluoric, and concentrated sul- phuric acids. It is not attacked by alkaline solutions, but with melted alkalies forms the alkali vanadates, with the evolution of hydrogen. The specific gravity of vanadium
is 5-5-
Compounds. A. Typical forms. The following may be considered typical compounds of vanadium:
Oxides V20 V2O2 V2O3 V2O4 V2O5
Chlorides VC12 VC13 VC14
Oxychlorides .... VOC1 VOC12
Bromide VBr3
Oxybromides VOBr2 VOBr3
Fluorides V2Fe+ 6H2O VF5
Double fluorides. . V2F6 with KF, CoF2, NiF2, etc.
Sulphides VaS, V2S3 V^O;,
V2S5 Sulpho salts Na3VS3O
(NH4)3VS4, etc.
Sulphate V202(S04)2
Nitrides VN VN2
Vanadates, ortho, R3VO4
Pyo, R4V207
meta, RVO3
complex, V2O5 with P2O5, MoO3, WO3, SiO2> AsO5, etc. B. Characteristics. The vanadium compounds are known in five conditions of oxidation, represented by the five oxides. Of these conditions the highest is the most
VAKADIUM. 87
stable and is known in the largest number of salts, the vanadates. Vanadic pentoxide is reddish yellow in color, and, like phosphoric pentoxide, it dissolves readily in the
alkali hydroxides and carbonates. The alkali vanadates
i thus formed are of the ortho, pyro, and meta types, (RgVO4 ;
RV2O7; RVO3). The vanadates are generally pale yellow in color. They are soluble in the stronger acids and with the exception of the alkali vanadates insoluble in water. Vanadic acid is easily reduced by reducing agents to the tetroxide condition, when the solution becomes blue. More powerful reducing agents carry the reduction further, to the trioxide, or even the dioxide condition, but only long- continued heating in a current of hydrogen brings about the reduction to the monoxide and the element.
Hydrogen sulphide, acting upon vanadic acid, reduces it to the tetroxide condition or even below, with a sepa- ration of sulphur. Ammonium sulphide gives the dark- brown solution of a sulpho salt, ((NH4)3S3VO?), and this solution, when acidified, gives a brown oxysulphide (V2S3O2). Vanadium resembles arsenic, phosphorus, and nitrogen, both in the chemical structure of its compounds and in their behavior toward reagents.
Estimation.* A. Gravimetric. Vanadium is usually weighed as the pentoxide, (V2O5), obtained (i) by precipi- tation of lead or barium vanadate, treatment with sulphuric acid, filtration, evaporation of the filtrate, and ignition; (2) by precipitation of mercury vanadate and ignition, the pentoxide being left; or (3) by precipitation of the ammo- nium salt by ammonium chloride and ignition (Berzelius, Pogg. Annal. xxn, 54; Gibbs, Amer. Chem. Jour, v, 371; Gooch and Gilbert, Amer. Jour. Sci. [4] xiv, 205).
* See Die analytische Chemie des Vanadins, V. von Klecki, pub. by Leo- pold Voss, Hamburg, 1894.
88 THE RARER ELEMENTS.
B. Volumetric. Vanadium may be estimated volu- metrically (i) by reduction from the condition of the pent- oxide to that of the tetroxide by sulphur dioxide, and re- oxidation by permanganate (Hillebrand, Jour. Amer. Chem. Soc. xx, 461); (2) by effecting the reduction by boiling with hydrochloric acid or with potassium bromide or iodide in acid solution, according to the typical equation V2O5 + 2HCl = V2O4-f H2O + C12. The chlorine, bromine, or iodine may be distilled, and determined by suitable means in the distillate (Holverscheit, Dissertation, Berlin, 1890; Fried- heim, Ber. Dtsch. chem. Ges. xxvm, 2067; Gibbs, Proc. Amer. Acad. x, 250; Gooch and Stookey, Amer. Jour. Sci. [4] xiv, 369; Curtis, Amer. Jour. Sci. [4] xvi), or the residue after boiling may be rendered alkaline by potas- sium bicarbonate, and reoxidation effected by standard iodine solution (Browning, Amer. Jour. Sci. [4] n, 185); (3) or the reduction may be accomplished by boiling with tartaric, oxalic, or citric acid, and reoxidation effected as outlined above (Browning, Zeitsch. anorg. Chem. vn, 158, and Amer. Jour. Sci. [4] n, 355).
Separation. Vanadium may be separated from the majority of the metallic bases (i) by fusion of material containing it with sodium carbonate and potassium nitrate and extraction with water, vanadium dissolving as sodium vanadate; or (2) by treatment of a solution containing a vanadate with ammonium sulphide in excess, vanadium remaining in solution as a sulpho salt.
From arsenic vanadium may be separated (i) by treat- ment with hydrogen sulphide, after reduction by means of sulphur dioxide, the arsenic being precipitated as the sulphide As2S3; (2) by heating the sulphides of vanadium and arsenic in a current of hydrochloric -acid gas at 150° C., the arsenic forming a volatile compound (Field and Smith, Jour. Amer. Chem. Soc. xviu, 1051).
From phosphorus vanadium may be separated by re-
EXPERIMENTAL WORK ON YANAD1UM. 89
duction of vanadic acid by means of sulphur dioxide, and precipitation of the phosphorus as phosphomolybdate.
From molybdenum the separation may be accomplished by the action of hydrogen sulphide upon a solution of vana- dic and molybdic acids under pressure, — molybdenum sul- phide being precipitated, — or by the action of ammonium chloride in excess upon a solution containing an alkali vanadate and molybdate, — ammonium metavanadate being precipitated (Gibbs, Amer. Chem. Jour, v, 371).
From tungsten vanadium may be separated by the ammonium chloride method (vid. Separation from molyb- denum, above) (Gibbs, Amer. Chem. Jour, v, 379).
EXPERIMENTAL WORK ON VANADIUM.
Experiment 82. Extraction of vanadic pentoxide from vanadinite, ((PbCl)Pb4(V04)3). Treat a few grams of the finely powdered mineral with nitric acid, heat until nothing further dissolves, dilate and filter. Remove the lead from the filtrate by hydrogen sulphide, filter again, and evaporate the filtrate to dryness, adding a little nitric acid after the hydrogen sulphide has boiled out, to insure the oxidation of the vanadium. Ignite the residue.
Experiment 83. Formation of insoluble vanadate s of
ii ii
lead, silver, and barium, (R3(VO4)2, ortho; or R(VO3)2, meta).
(a) To a solution of an alkali vanadate (ortho or meta) add a solution of lead acetate.
(b) Repeat the experiment, substituting silver nitrate for lead acetate. Note the flocky character of the pre- cipitate when shaken.
(c) Use barium chloride as the precipitant.
(d) Try the action of nitric and acetic acids upon these salts.
9° THE RARER ELEMENTS.
Experiment 84. Formation of vanadium pentoxide, (V205) , from ammonium vanadate. Evaporate a solution of am- monium vanadate to dryness and ignite. Note the crystals of the pentoxide.
Experiment 85. Precipitation of vanadium oxy sulphide, (V2S3O2). (a) To a solution of an alkali vanadate add ammonium sulphide. Note the darkening in color ((NH4)3S3VO?). Acidify the solution with hydrochloric acid. Note the precipitation of the oxysulphide.
(b) Note that hydrogen sulphide in an acid solution precipitates sulphur and leaves a blue solution (V2O4).
Experiment 86. Reduction of vanadic acid, (V205). (a) To a solution of an alkali vanadate add a crystal of tartaric acid and boil. Note the yellow-red color of the vanadic acid when the tartaric acid is first added, and the change to blue (V2O4) produced on boiling.
(b) Neutralize the blue solution obtained in (a) with sodium or potassium bicarbonate, and add a solution of iodine in potassium iodide until, after the liquid has stood for a few moments, the color of the iodine remains. Bleach the excess of iodine with an alkaline solution of arsenious oxide. Note that the blue color has disappeared and the vanadium is in the condition of the pentoxide (V2O5).
(c) Try the action of other reducing agents upon vanadic acid, e.g. oxalic acid, hydrochloric acid, stannous chloride, zinc and hydrochloric acid, etc. Note that the zinc and hydrochloric acid carry the reduction below the tetroxide condition (V2O4).
Experiment 87. Delicate tests for vanadium, (a) Acidify a solution of an alkali vanadate and add hydrogen dioxide. Note the red color (Maillard).
(b) Bring a few drops of the vanadium solution into contact with a drop of strong sulphuric acid to which a crystal of strychnine sulphate has been added Note the color, changing from violet to rose.
MOLYBDENUM. 91
Experiment 88. Borax-bead tests for vanadium. Fuse a little ammonium vanadate into a borax bead and test the action of the reducing and oxidizing flames upon it.
MOLYBDENUM, Mo, 96.
Discovery. The name Molybdena, derived from lead, was originally applied to a variety of substances con- taining lead. Later the term was used to designate only graphite and a mineral sulphide of molybdenum which is very similar in appearance to graphite, and which was confused with it. In 1778 Scheele, in his treatise on molyb- dena (Kong. Vet. Acad. Handl. (1778), 247), showed that it differs from plumbago, or graphite, in that on being heated with nitric acid it yields a peculiar white earth, which he proved to be an acid-forming oxide. This he called "acidum molybdenae, " and he supposed the mineral to be a compound of this oxide with sulphur. In 1790 Hjelm (ibid. (1790), 50; Ann. de Chim. iv, 17) isolated the ele- ment.
Occurrence. Molybdenum occurs in combination in minerals which are somewhat widely diffused, though found in small amounts:
Contains Mo
Molybdite, MoO3 66-67%
Molybdenite, MoS2 60%
Powellite, Ca(Mo,W)O4 58-59%*
Wulfenite, PbMoO4 37-40%*
Belonesite, MgMoO4? 78-79%*
Scheelite, CaWO4 traces- 8%*
Extraction. Molybdenum salts are usually obtained from molybdenite, the most abundant ore, though some-
*MoO8.
92 THE RARER ELEMENTS.
times from other minerals. The following processes will illustrate the methods employed.
(1) From molybdenite. The mineral is roasted until sulphur dioxide is no longer given off and the residue is yellow when hot and white when cold. This residue is dissolved in dilute ammonium hydroxide, and the solution is evaporated to crystallization. Heat drives off the ammonia from the crystals and leaves the trioxide of molybdenum.
(2) From molybdenite. The mineral is treated with nitric acid (vid. Experiment 89).
(3) From wulfenite. The mineral is fused with potas- sium polysulphide. Upon extraction with water the lead remains insoluble, as the sulphide, and the molybdenum goes into solution as the sulpho salt. The filtrate is acidi- fied with sulphuric acid, and the sulphide of molybdenum is precipitated (Wittstein).
The Element. A. Preparation. Elementary molybde- num may be prepared (i) by passing dry hydrogen over either the trioxide or the ammonium salt at red heat, and (2) by reducing the chlorides with hydrogen.
B. Properties. Molybdenum is a gray metallic powder, which is unchanged in the air at ordinary temperatures, but which, when heated, passes gradually into the trioxide. It is insoluble " in hydrochloric, hydrofluoric, and dilute sulphuric acids, but soluble in nitric and concentrated sulphuric acids, in aqua regia, in chlorine water, and in melted potassium hydroxide, and potassium nitrate. Its specific gravity is 8.6.
Compounds. A. Typical forms. The following are typ- ical compounds of molybdenum:
Oxides MoO Mo2O3 MoO2 Mo8Ou Mo3O8 MoO3
Chlorides Mod, MoCl3 MoCl4 MoCIa
Oxychlorides. MoOC^
Mo03da Bromides.... MoBra MoBr9 MoBr4
MOLYBDENUM 93
Oxybromide.. MoOaBra
Oxyiodide.... MoO2I
Oxyfluorides . MoOF^ • 2KF
+ H.O
MoO2F2-KF
+ H20 Sulphides .... MoS2 MoS3 ; MoS4
Sulphosalt... R2MoS4
i Molybdates, many salts of the type R2MoO4, as K2MoO4; CaMoO4; ZnMoO4;
Ag2MoO4; etc.
Molybdenum trioxide combines with phosphoric pent- oxide in the following proportions: P2O5 : MoO3 : : i : 24, 1:22, 1:20, 1:18, 1:16, 1:15, 1:5, as 2K2HPO4-24MoO3 + 3H2O; 2(NH4)3PO4-i6MoO3 + i4H2O; etc. It combines with arsenic pentoxide as follows : As2O5 : MoO3 : : i : 20, 1:18, 1:16, 1:6, 1:2, as As2O5«2oMoO3-f 27H2O; ioNH3-As2O5-i6MoO3 + i4H2O; etc.
B. Characteristics. The molybdenum compounds are known in various conditions of oxidation (vid. Typical Forms), of which the highest, (MoO3), is the most stable and comprises the largest number of salts. The trioxide is white to pale yellow, and dissolves in potassium, sodium, and ammonium hydroxides, forming the molybdates. When strong reducing agents, such as zinc and hydro- chloric acid, act upon acid solutions of molybdates, the reduction is said to go as far as the oxide Mo5O7, the solu- tion passing through the colors of the various oxides, violet, blue, and black. The oxide Mo5O7, however, is very sensitive to oxidation, for it is changed in the air to the sesquioxide (Mo2O3) as soon as the reducing action has ceased. Acid solutions of the lower oxides give, on treatment with the alkali hydroxides, the corresponding hydroxides of molybdenum, Mo2O3 • 3H2O ; MoO2 -^H2O ; etc. The sulphide (MoS3) is obtained by treating a molybdate with ammonium sulphide and acidifying. Its color is reddish brown.
Estimation. A. Gravimetric. Molybdenum is generally
94 THE RARER ELEMENTS.
weighed as the oxide (MoO3), obtained (i) by ignition of ammonium molybdate; (2) by precipitation of mercury molybdate and ignition; or (3) by precipitation of the sulphide and conversion into the oxide by treatment with nitric acid.
B. Volumetric. Soluble molybdates may be reduced in acid solut'on by boiling with potassium iodide, and the iodine thus liberated may be passed into potassium iodide and estimated by standard thiosulphate, the amount of molybdenum present being calculated from the equation 2MoO3+2HI=Mo2O5 + I2+H3O; or, after the iodine has been removed by boiling, the residual solution may be rendered alkaline by potassium bicarbonate and reoxidized by standard iodine solution or potassium permanganate (Mauro and Danesi, Zeitsch. anal. Chem. xx, 507 ; Fried- heim and Euler, Ber. Dtsch. chem. Ges. xxvm, 2066; Gooch and Fairbanks, Amer. Jour. Sci. [4] n, 156; Gooch and Pulman, Amer. Jour. Sci. [4] xn, 449).
Separation. The general methods for the separation of molybdenum from the metals and alkali earths are the same as those described under Vanadium.
From arsenic and phosphorus, when present as arsenic and phosphoric acids, molybdenum may be separated by magnesium chloride mixture in ammoniacal solution, ammonium-magnesium arseniate and phosphate being precipitated (Gibbs, Amer. Chem. Jour, vn, 31.7; Gooch, Amer. Chem. Jour, i, 412).
For the separation from vanadium, vid. Vanadium.
From tungsten molybdenum may be separated (i) by the action of warm sulphuric acid of specific gravity 1.37 upon the oxides (MoO3 and WO3), molybdic acid dissolv- ing (Ruegenberg and Smith, Jour. Amer. Chem. Soc. xxii, 772) ; (2) by heating the oxides with hydrochloric- acid gas at 25o°-27o° C., the molybdenum compound (MoO3-2HCl) being volatilized (Pechard, Compt. rend.
EXPERIMENTAL WORK ON MOLYBDENUM. 9$
cxiv, 173; Debray, ibid. XLVI, noi); (3) by precipitation of the, sulphide of molybdenum by means of hydrogen sulphide in the presence of tartaric acid (Rose, Handbuch der anal. Chemie (sechste Auflage, 1871), 358).
EXPERIMENTAL WORK ON MOLYBDENUM.
Experiment 89. Extraction of molybdenum salts from molybdenite, (MoS2). Heat 5 grm. of the finely powdered mineral with nitric acid until the dark color has disap- peared. Evaporate to dryness, wash the residue in warm d'lute nitric acid, then in water, and dissolve it in am- monium hydroxide. Filter, and evaporate the filtrate to a small volume. Ammonium molybdate crystallizes out, which may be converted into the trioxide by careful ignition.
Experiment 90. Precipitation of the sulphides of molyb- denum, (MoS2; MoS3). (a) Through a solution of am- monium molybdate acidified with hydrochloric acid pass hydrogen sulphide. Note the gradual change of color of the solution, from red-brown to blue, and the partial precipitation of the sulphide MoS2.
(6) To a solution of ammonium molybdate add am- monium sulphide, or pass hydrogen sulphide through an alkaline solution of a molybdate. Note the yellow-brown color ((NH4)2MoS4, typical). Acidify the solution and note the brown precipitate (MoS3).
Experiment 91. Precipitation of ammonium phospho- molybdate (3(NH4)2O.P2O5.24(MoO3) -f 2H2O). To a solu- tion of ammonium molybdate acidified with nitric acid add a drop of a solution of sodium phosphate, and warm gently. Note the yellow precipitate.
Experiment 92. Precipitation of the molybdates of silver, lead, and barium, (Ag2MoO4, PbMoO4, and BaMoO4, typical). To separate solutions of ammonium molybdate,
9<* THE RARER ELEMENTS.
neutral or faintly acid with acetic acid, add solutions of silver nitrate, lead acetate, and barium chloride respec- tively. Note the solvent action of nitric acid upon the precipitates.
Experiment 93. Reduction of molybdic acid, (MoO3). (a) Put a piece of metallic zinc into a solution of ammo- nium molybdate and add hydrochloric acid until the action starts. Note the change in color of the solution as the reduction proceeds (reddish yellow, violet, bluish, black). To a few drops of the solution after reduction add potas- sium or sodium hydroxide. Note the dark-brown pre- cipitate of the lower hydroxides of molybdenum (Mo2(OH)6, etc.) mixed with the hydroxide of zinc.
(b) Try the reducing action of stannous chloride upon a molybdate in solution.
(c) To a dilute solution of a molybdate which has been treated with zinc and hydrochloric acid, add some potas- sium sulphocyanide in solution. Note the red color. Try the effect of adding ether and shaking.
Experiment 94. Preparation of elementary molybde- num from ammonium molybdate. Heat a few grams of finely powdered ammonium molybdate until no further test for ammonia is obtained when a piece of moistened red litmus paper is held over the substance. Remove the molybdic trioxide thus obtained to a Rose crucible and heat for some time in a current of hydrogen. Note the gray powder.
TUNGSTEN, W, 184.
Discovery. The minerals scheelite, formerly called tungsten (i.e. "heavy stone"), and wolframite have long been known, but until about the middle of the eighteenth century they were regarded as tin ores. In 1781 Scheele (Kong. Vet. Acad. Handl. (1781), 89) demonstrated that scheelite contained a peculiar acid which he named Tung-
TUNGSTEN. 97
stic acid. Two years later the brothers D'Elhujar showed the presence of the same acid in wolframite.
Occurrence. Tungsten is found combined in minerals which are often associated with tin ores:
Contains W03.
Wolframite, (Fe,Mn)WO4. 74~?8%
Scheelite, CaWO4 71-80%
Hubnerite, MnWO4 73~77%
Cuprotungstite, CuWO4. 56-57%
Cuproscheelite, (Ca,Cu)WO4 76-80%
Powellite, Ca(Mo,W)O4 10-11 %
Stolzite, PbWO4 51 circa
Raspite, PbWO4 49
Reinite, FeWO4 75-76%
Tungstite, WO3 100 circa
Extraction. Tungstic acid is usually extracted from wolframite. Either of the processes here indicated may be followed :
(1) 5 parts of the mineral are fused with 8.5 parts of dry sodium carbonate and 1.5 parts of sodium nitrate. On treatment of the fused mass with water, sodium tung- state is dissolved, and after filtration tungstic acid is pre- cipitated by hydrochloric acid.
(2) The mineral is decomposed by hydrochloric acid (vid. Experiment 95).
The Element. A. Preparation. Elementary tungsten may be obtained (i) by heating the acid in the presence of hydrogen; (2) by heating the chloride (WC16) in the presence of hydrogen; (3) by heating the acid with carbon; (4) by heating the nitride.
B. Properties. Tungsten is a very hard powder rang- ing in color from gray to brownish black, resembling some- times tin, sometimes iron. Although unchanged in the air
98 THE RARER ELEMENTS.
at ordinary temperatures, when heated in finely divided condition it ignites and burns to the oxide (WO3). It dissolves when heated with sulphuric, hydrochloric, and nitric acids. It is attacked by dry chlorine at high temper- atures; also by concentrated boiling potassium hydroxide, with the formation of potassium tungstate. The specific gravity of tungsten is from 16.5 to 19.1.
Compounds. A. Typical forms. The following com- pounds of tungsten may be considered typical:
J
Oxides* WO3\ WO*
Chlorides WC1, WC14 WC15 WClfl
Oxychlorides WOC14
WO2C12
Bromides WBr2 WBr5
Oxybromides WOBr4
W02Br2
Iodide WI3
Double fluorides . . KF • WO2F+ H2O ZnF2 • WO2F2+ ioH2O ;
etc.
Sulphides WS2 WS3
Sulpho salts R2WS4
R2WS202 R2WSO3
Tungstates, many salts of the types, R2WO4 (normal)
R2W4O13 (meta) ReW7024 (para)
Tungstic trioxide (acid) combines with phosphoric pentoxide, arsenic pentoxide, and silicon dioxide in the following proportions:
P2O5: WO3: : i : 22, i : 21, i : 20, i : 16, 1:12, 1:7. As2O5 :WO3:: i : 16, i : 6, i : 3. SiO2: WO3: : i: 12, i: 10.
B. Characteristics. The compounds of tungsten are very similar to those of molybdenum, and are known
* Some authorities give three oxides between the dioxide and the trioxide, viz., W2O5, W3O8, and W4OU.
TUNGSTEN. 99
in several conditions of oxidation (vid. Typical Forms), of which the highest is the most stable. The trioxide, (WO3), united with the bases, forms the largest number of salts, the tungstates. When acted upon by reducing agents, tungstic acid or trioxide may be reduced to the dioxide, (WO2), the solution becoming blue, then brown. When the solution of a tungstate is acidified, tungstic acid is precipitated. Tungstic sulphide, (WS3), is obtained under the same conditions as molybdenum sulphide, and is brown. It dissolves in ammonium sulphide, forming a sulpho salt.
Estimation. Tungsten is ordinarily weighed as the oxide (WO 3), obtained (i) by igniting ammonium tungstate; (2) by decomposing the alkali tungstates with nitric acid, evaporating to dryness, and extracting with water, — tung- stic acid remaining undissolved; (3) by precipitating mer- cury tungstate and driving off the mercury by means of heat, leaving the acid or oxide ; (4) by boiling fused lead tungstate with strong hydrochloric acid, — tungstic acid being precipitated (Brearley, Chem. News LXXIX, 64).
Separation. Tungsten may be separated from the me- tallic bases and many other elements by the following process : fusion with an alkali carbonate, extraction of the alkali tungstate with water, acidification with nitric acid, evaporation to dryness, and extraction with water, — tung- stic acid remaining undissolved.
For the separation of tungsten from molybdenum and vanadium, see those elements. From arsenic and phos- phorus tungsten is separated by magnesium mixture (Gooch, Amer. Chem. Jour, i, 412; Gibbs, Amer. Chem. Jour, vii, 337).
From tin the separation may be accomplished (i) by ignition with ammonium chloride, tin chloride being vola- tilized (Rammelsberg) ; (2) by fusion with potassium cyanide, the tin being reduced to the metal and the tungsten being converted into a soluble tungstate (Talbot).
loo THE RARER ELEMENTS.
EXPERIMENTAL WORK ON TUNGSTEN.
Experiment 95. Extraction of tungstic acid from wol- framite ((Fe,Mn)WO4). Treat 5 grm. of the finely powdered mineral with about 10 cm.3 of a mixture of equal parts of hydrochloric acid and water, and boil as long as any action seems to take place. Decant the solution, add to the residue about 10 cm.3 of a mixture of nitric and hydro- chloric acids (aqua regia), and warm. Add more acid if necessary, and continue this treatment until the residue is yellow, then filter and wash. Warm the yellow mass with ammonium hydroxide as long as any solvent action is observed, and filter. Evaporate the filtrate to dryness and ignite the ammonium tungstate to obtain tungstic acid.
Experiment 96. Formation of sodium tungstate, (Na2WO4, typical). Dissolve a little tungstic acid in a solution of sodium carbonate.
Experiment 97. Precipitation of tungstic sulphide, (WS3), and formation of the sulpho salt ((NH4)2WS4). (a) To a solution of sodium or ammonium tungstate add ammo- nium sulphide, and acidify with hydrochloric acid.
(6) Try the action of hydrogen sulphide upon a soluble tungstate.
(c) Try the action of ammonium sulphide upon tungstic sulphide.
Experiment 98. Precipitation of tungstic acid, (WO3). Acidify a concentrated solution of a tungstate with hydro- chloric or nitric acid and boil.
Experiment 99. Precipitation of barium, lead, and silver
i tungstates, (R2WO4, typical). To separate portions of a
solution of sodium tungstate acidified with acetic acid add solutions of barium, lead, and silver salts respectively.
Experiment 100. Reduction of tungstic acid, (a) To a solution of a tungstate (e.g. sodium tungstate) add a
URANIUM. 1 01
solution of stannous chloride. Acidify with hydrochloric acid and warm gently.
Experiment 101. Salt of phosphorus bead tests. Make a bead of microcosmic salt, and heat it in the oxidizing and reducing flames with a small particle of tungstic acid. Try the effect of a small amount of ferrous sulphate upon the bead heated in the reducing flame.
URANIUM, U, 238.5.
Discovery. Klaproth, in the year 1789, discovered that the mineral pitch-blende, supposed to be an ore of zinc, iron, or tungsten, contained a "half-metallic substance'* differing in its reactions from all three (Crell Annal. (1789) ii, 387). This he named Uranium in honor of Herschel's discovery of the planet Uranus in 1781. The body that Klaproth obtained was really an oxide of uranium, as Peligot showed in 1842, when he succeeded in isolating the metal (Ann. de Chim. (1842) v, 5).
Occurrence. Uranium is found combined in a few min- erals, most of them rare. Pitch-blende is the most abun- dant source.
Uraninite (pitchblende), UO3 • UO2 - PbO • N, etc., contains 75-85% (UO2+ UOj)
Gummite, (Pb,Ca)U3SiO12-6H2O?, " 61-75% UO3
Thorogummite, UO3-3ThO2-3SiO2-6H2O, " 22-23% "
Mackintoshite, UO2 • 3ThO2 • 3SiO2 • 3H2O, " 2 1-22% UO2
Uranophane, CaO • 2UO3 • 28! O2 • 6H2O, " 53-67% UO3
Uranosphaerite, (BiO)2U2Or 3H2O, " 50-51% "
Walpurgite, Bi10(UO2)3(OH)24(AsO4)4, " 20-21% "
Carnotite, K2O • 2U2O3 • V2O5 • 3H2O, " 62-65% U2O,
Torbernite, Cu(UO2)2P2O8-8H2O, " 57-62% UO8
Zeunerite, Cu(U02)2As208-8H2O, " 55-56% "
Aitfcmtte,Ca(U02),P2(V8HaO, 55-62% "
Uranospinite, Ca(UO2)2As2O8-8H2O, " 59~6o% "
Uranocircite, Ba(U02)2P2O8-8H2O, 56-57% "
Johannite, sulphate, formula doubtful, 67-68% "
Uranopilite, CaO.8UO3.2SO3-25H3O, " 77~78% "
Thorite, ThSiO4, " 1-10% •«
102
THE RARER ELEMENTS.
Phosphuranylite, (UO2)3P2O8-6H2O, Trogerite, (UO2)3As2O8 • 1 2H2O,
Uranothallite, 2CaCO3 • U(CO3)2 -xioH2O, Liebigite, CaCO3 • (UO2)CO3 • 2oH2O, Voglite, complex carbonate,
Hatchettolite, R(Nb,Ta)2Oc.H2O,
in Ferguson! te, R(Nb,Ta)O4,
Sipylite, complex niobate,
n in Samarskite, R3R2(Nb,Ta)8O21,
o
Annerpdite, complex, Hielmite, complex,
in in
Euxenite, R(NbO3)3 • R2(TiO3)3 • |H2O,
in in
Polycrase, R(NbO3)3.2R(TiO3)3-3H2O,
contains.
M
72-77% UOS 63-64% "
35-37% U02
36-38% UO,
37% U02
15-16% U08
o- 8% U02
3-4% "
10-13% U08
16-17% UO2
0-5% '
1-19% "
Extraction. Uranium salts may be extracted from pitch- blende as follows:
(1) The mineral is decomposed with nitric acid, the acid solution is evaporated to dryness, and the mass is extracted with water. The residue, which consists largely of lead sulphate, iron arseniate, and iron oxide, is filtered off, and on evaporation of the solution impure nitrate of uranium crystallizes out, which may be purified by re- crystallization ( Peligot) .
(2) The mineral is decomposed by aqua regia (vid. Experiment 102).
The Element. A. Preparation. Metallic uranium may be obtained (i) by heating a mixture of the chloride UC1S with sodium and potassium chloride in a porcelain cru- cible surrounded by powdered carbon contained in another crucible (Peligot) ; (2) by heating a mixture of uranium chloride, sodium chloride, and metallic sodium in a closed iron crucible.
B. Properties. Uranium is a somewhat malleable white metal with much the appearance of nickel. Heated in air or oxygen to a temperature of 1 50°-! 70° C. it burns
UR/4N1UM. I03
to the oxide ; at ordinary temperatures the oxidation takes place slowly. Uranium dissolves slowly in cold dilute sul- phuric acid, and more rapidly upon the application of heat. It is soluble in nitric and hydrochloric acids. It is attacked by chlorine at i5o°C. and by bromine at 240° C. The caustic alkalies have no apparent action upon the element. The specific gravity of uranium is 18.6.
Compounds. A. Typical forms. The following are typ- ical compounds of uranium:
Oxides * UOa U3O8(UO2 +
2UO3) UO3
Carbonates UO2CO3 • 2K2CO3
U02C03-2(NH4)2C03
Chlorides UC13 UC14 UC15 UO2C12
Bromides UBr3 UBr4 UBr8 UO2Br2
lodate U02(I03)2
Fluorides UF4 UO2F2
UO2F2-NaF, etc. Sulphides US UjS, US2 UOS2
U02S
Sulphates U(SO4)2+ UO2SO4+ 3|H2O
4H20
Nitrate UO2(NO3)2+ 6H2O
Nitride U3N4
Ferrocyanides UFe(CN)8 (UO2)3K2(FeC8N8),
Phosphates, ortho. UOHPO4 (UO2)5H2(PO4)4
pyro.. (UO)2P207 (UO2)2P2O7
meta.. UO(PO3)2 UO2(PO3)2
Arseniate UO2H AsO4+ 4H2O
Uranates, of types R2UO4> R2U2O7, and R4UO8.
B. Characteristics. Uranium differs from vanadium, molybdenum, and tungsten in manifesting less marked acidic qualities. The chief classes of salts are the uranyl, in which uranium shows its highest degree of oxidation, corresponding to the oxide UO3 (e.g. UO2C12), and the uranous, of which the oxide UO2 is the type (e.g. UC14). The uranyl salts are the more stable and better known. They may be reduced by zinc and hydrochloric acid to
* Other oxides less well known than those given above are of the follow- ing forms: UO, U2O3, U3O4, and UO4.
104 * THE RARER ELEMENTS.
the lower condition. The uranous salts are easily oxidized to the higher form. The uranyl salts are, in general, yellow, the uranous greenish. The two conditions of oxidation may be further distinguished by the following reactions: the precipitate resulting from the action of ammonium sulphide upon uranyl salts is reddish brown, — upon uranous salts, light green; the precipitate resulting from the action of potassium ferrocyanide upon uranyl
salts is blood-red, — upon uranous salts yellowish green.
i i
Uranates of the types R2UO4 and R2U2O7 are formed by
the combination of the oxide UO3 with the strong bases.
Estimation.* A. Gravimetric. Uranium may be weighed (i) as urano-uranic oxide (U3O8), obtained by precipitation of ammonium uranate by means of ammonia, and ignition in air or oxygen; (2) as urano-uranic oxide, precipitated electrolytically by a current of 0.18 ampere and 3 volts at a temperature of 70° C. (Smith and Wallace, Jour. Amer. Chem. Soc. xx, 279; Smith and Kollock, ibid, xxm, 607); (3) as uranous oxide (UO2), obtained by ig- nition of urano-uranic oxide in a current of hydrogen; (4) as the pyrophosphate ((UO2)2P2O7), obtained by pre- cipitation by means of ammonium phosphate in the pres- ence of ammonium acetate, and ignition.
B. Volumetric. Uranium may be estimated volumet- rically by reduction from the higher (UO3) to the lower ,(UO2) condition of oxidation by means of zinc and sul- phuric acid, and oxidation with permanganate, according to the following formulae (Pulman, Amer. Jour. Sci. [4] xvi) :
(1) U02S04 + Zn + 2H2S04= ZnSO4 + U(SO4)
(2) 2KMn04 + 5U(S04)2 + 2H20=
2KHSO4 + 2MnSO4 + H2SO4
Separation.* From the metals which precipitate sul- phides with hydrogen sulphide in acid solution, uranium * Vid. Kern, Jour. Amer. Chem. Soc, XXHI, 685.
EXPERIMENTAL WORK ON URANIUM. 105
may be separated by hydrogen sulphide. From iron, nickel, and other members of its own group it may be separated by ammonium sulphide in the presence of an excess of sodium or ammonium carbonate, the uranium salt remaining in solution. From the alkalies and alkali earths the separation may be accomplished by means of ammonium sulphide in the presence of ammonium chloride, uranium oxysulphide being precipitated.
EXPERIMENTAL WORK ON URANIUM.
Experiment 102. Extraction of uranium salts from pitch" blende. Warm 5 grm. of pulverized pitch-blende with aqua regia until the decomposition is complete, and remove the excess of acid by evaporation. Extract with water and boil the solution a few minutes with sulphurous acid to reduce the arsenic acid. When the liquid is at about 60° C., pass hydrogen sulphide through to the complete precipita- tion of arsenic, copper, lead, bismuth, and tin. Filter, oxidize the filtrate with nitric acid, and precipitate with ammonium hydroxide. Treat the precipitate with hot concentrated ammonium carbonate, filter, and allow the filtrate to cool. The double carbonate of uranium and ammonium will separate. A further precipitate, of crude ammonium uranate, may be obtained by boiling the mother- liquor.
Experiment 103. Precipitation of sodium, potassium,
i or ammonium uranate, (RJJfi?, typical). To a solution
of a uranyl salt add sodium, potassium, or ammonium hydroxide. Note the yellow color of the precipitate and the insolubility in excess of the reagent. Repeat the experiment with tartaric acid present in the solution.
Experiment 104. Formation of the soluble double car- bonates of uranium with sodium or potassium, and uranium
lo6 THE RARER ELEMENTS.
with ammonium, (UO-jCOg^R/X),,) • (a) To a solution of a uranyl salt add a solution of sodium or potassium car- bonate, noting the first and the final effects. Try the re- sult of boiling, and of adding sodium or potassium hydrox- ide to a separate portion of the clear solution.
(b) Try similarly the action of ammonium carbonate upon a uranyl salt in solution. Note the ready solvent action of an excess of the carbonate, and the precipitation of ammonium uranate, ((NH4)2U2O7), on boiling.
(c) To a solution of a uranyl salt add hydrogen di- oxide and potassium or sodium carbonate. Note the cherry-red color (Aloy).
Experiment 105. Precipitation of uranyl ferrocyanide, ((U02)3K2(FeC6N6)2 or (UO2)2FeC6N6). (a) To a very dilute solution of a uranyl salt add a little potassium ferrocyanide in solution. Note the red precipitate. This is a delicate test for uranyl salts.
(b) Try similarly the action of potassium ferricyanide.
Experiment 106. Precipitation of uranyl phosphate, (UO2HPO4). To a solution of a uranyl salt add a solution of hydrogen disodium phosphate. Try the action of the common acids upon the precipitate.
Experiment 107. Precipitation of uranyl sulphide, (UO2S). (a) To a solution of a uranyl salt add ammonium sulphide. Note the dark-brown color of the precipitate, and the insolubility in excess of the reagent.
(b) Try the action of hydrogen sulphide upon a uranyl salt.
Experiment 108. Reduction of uranyl salts, (a) To a solution of a uranyl salt add zinc and sulphuric acid. Note the change of color from yellow to green.
(6) Bring about the reduction with magnesium and acid. Test the uranous salt in solution with potassium ferrocyanide and with ammonium sulphide.
TELLURIUM.
107
TELLURIUM, Te, 127.6.
Discovery. Native tellurium, which is quite widely distributed in small quantities, was a puzzle to the early mineralogists. Because of its non-metallic properties and its metallic luster it was known as aurum paradoocum and metallum problematicum. In 1782 Muller von Reichen- stein, after some careful work on this interesting substance, suggested that a peculiar metal might be present. Acting on the suggestion, Klaproth undertook an investigation, and in 1798 he demonstrated that the "metal" was not identical with any known element. He proposed the name Tellurium from tellus, earth (Crell Annal. (1798) i, 91).
Occurrence. Tellurium occurs in combination and also, sparingly, native.
Petzite, (Ag,Au)2Te, contains.. 32-35% Te
Goldschmidtite, Au-jAgTe^ " . . 59-60% "
Hessite, Ag,Te, " .. 37~44% "
Altaite, PbTe, " . . 37-38% "
Coloradoite, HgTe, " . . 38-39% "
Melonite, Ni2Te3, " . . 73-76% "
Kalgoorlite, HgAu.AgeTee, " .. 37-56% "
Sylvanite, (Au,Ag)Te2, " .. 58-62% "
Calaverite, (Au,Ag)Te2-AuTe2, " .. 56-58% "
Krennerite, (Au,Ag)Te2-AuTe2, " -.38-59% "
Nagyagite, Au2Pb14Sb3Te7S17, " .. 15-31% "
Tapalpite, 3Ag2(S,Te) -Bi2(S,Te)3?, " .. 20-24% "
Tetradymite, Bi2Te3S3, " .. 33-49% "
Grunlingite, Bi4TeS3, " ..12-13% "
Rickardite, Cu2Te • 2CuTe, " .. 59-60% "
Joseite, formula doubtful, " .. 15-16% "
Wehrlite, 4< " " 29-35% "
Stiitzite,Ag4Te?, " .. 22-23% "
Tellurite, TeO2, " .. 79-80% "
io8 THE R4RER ELEMENTS.
Montanite, Bi2(OH)4Te06?, contains.. 24-28% TeO3
Emmonsite, formula doubtful, " .. 59-60% Te
Durdenite, Fe2(Te03)3.4H20, " .. 47-64% TeO2
Tellurium (native), Te, " . . 93-97% Te
Selen-tellurium, 3Te2Se, " .. 70-71% "
Extraction. Tellurium may be extracted by the fol- lowing methods :
(1) From tellurium bismuth (tetradymite). The mineral is mixed with its own weight of sodium carbonate, and oil is added until the mass has the consistency of thick paste. This is heated strongly in a well-closed crucible and then extracted with water. The extract, containing sodium sulphide and sodium telluride, (Na2Te), is separated by filtration from the insoluble matter and left exposed to the air. The tellurium separates as a gray powder. It may be purified by distillation (Berzelius).
(2) From sylvanite or nagy agile. The mineral is treated with hydrochloric acid, which dissolves the antimony, arsenic, etc. The residue is dissolved in aqua regia, the excess of acid is removed by evaporation, and the gold is precipitated by ferrous sulphate. After the removal of the gold by filtration the tellurium is precipitated by sul- phur dioxide (Von Schrotter).
(3) From flue-dust containing tellurium. The material is treated with strong commercial hydrochloric acid (vid. Experiment 109).
The Element. A. Preparation. Elementary tellurium may be obtained (i) by the action of reducing agents, as sulphurous acid or stannous chloride, upon the salts of tel- lurium; and (2) by the action of air upon soluble tellurides.
B. Properties. Tellurium is generally considered a non- metal, though Berzelius classed it with the metals. It is known in two conditions: (i) the crystalline, in which the element has a luster like silver, and (2) the amorphous. It
TELLURIUM.
109
is unchanged in the air at ordinary temperatures, but when heated in air or oxygen it burns with a green flame, forming the dioxide (TeO2). It is not attacked by hydrochloric acid, but is acted upon slowly by concentrated sulphuric acid, with evolution of sulphur dioxide. It is oxidized by nitric acid and aqua regia to tellurous acid, (H2TeO3), and is dissolved in hot caustic potash, forming the telluride and tellurite (K2Te; K2TeO3). It combines with metals to form tellurides. Like selenium and sulphur, it is a poor conductor of heat and electricity. Its specific gravity is from 6.1 to 6.3.
Compounds. A. Typical forms. The following are typ- ical compounds of tellurium:
Oxides TeO
Chlorides TeCl2
Oxychloride
Bromides TeBr2
Oxybromide
Iodides TeI2
Fluoride
Double fluoride
Sulphite TeSO,
Sulphate '.....
Sulphides (or sulpho salts).
TeO2
TeCl4
TeOCl2
TeBr4
TeOBr2
TeI4
TeF,
TeF!
TeO3
KF
2TeO2-SO3 TeS2.3K2S TeS2-Bi2S3, etc.
H2TeO4*
Tellurides H2Te
As2Te3
K2Te, etc.
Acids (tellurous and telluric) H2TeO3
Salts (tellurites and tellurates) R2TeO3 R2TeO4
B. Characteristics. The compounds of tellurium closely resemble in general structure those of sulphur, and, as will appear later, those of selenium. Hydrogen telluride, (H2Te) ,
* Gutbier favors the formula HcTeOn.
no THE RARER ELEMENTS.
like hydrogen sulphide, is a gaseous substance, and it pre-
i cipitates metallic tellurides, (R2Te) , similar to the sulphides.
Two oxides, tellurous, (TeO2), and telluric, (TeO3), are well known,* but, unlike the corresponding oxides of sulphur, they are very sparingly soluble in water. The acids, (H2TeO3; H2TeO4), may be formed by acidifying solutions of the alkali salts (e.g. Na2TeO3 or Na2TeO2) which have been formed by the action of the alkali hydroxides upon the oxides (TeO2; TeO3). Many tellurites and tellurates, (R2TeO3; R2Te04), may be formed by treating the alkali tellurites or tellurates with soluble salts of the various bases. Two chlorides are known, (TeCl2; TeCl4), both of which are decomposed by water. The corresponding bromides and iodides are also known. In general, com- pounds of tellurium are easily reduced to the element. The reduction, however, is not accomplished quite so readily as in the case of selenium compounds.
Estimation. f A. Gravimetric. Tellurium is usually weighed as the element, obtained by treating solutions of tellurium compounds (i) with sulphur dioxide; (2) with hydrazine sulphate in ammoniacal solution (Jan- nasch, Ber. Dtsch. chem. Ges. xxxi, 2377); (3) with hydra- zine hydrate or its salts in acid or alkaline solution (Gut- bier, Ber. Dtsch. chem. Ges. xxxiv, 2724); (4) with sul- phur dioxide and potassium iodide (Frericks, J. pr. Chem. [2] LXVI, 261); (5) with hypophosphorus acid (Gutbier, Zeitsch. anorg. Chem. xxxn, 295) ; (6) with grape-sugar in alkaline solution (Stolba, vid. Kastner, Zeitsch. anal. Chem. xiv, 142) ; or (7) with acid sodium sulphite or mag- nesium (vid. Experiment 109).
It may be weighed also as the sulphate, (2TeO2-SO3),
* A monoxide, (TeO), also has been described.
t See Gutbier, Studien uber das Tellur, pub. by Hirschfeld, Leipzig, 1902; Mac Ivor, Chem. News LXXXVII, 17, 162.
TELLURIUM. Hi
obtained by treating elementary tellurium with a mixture of nitric and sulphuric acids and evaporating (Metzner, Ann. Chim. Phys. [7] xv, 203).
B. Volumetric. Tellurium may be estimated volumet- rically (i) by the reduction of telluric acid to tellurous by means of potassium bromide in sulphuric acid solution, (H2TeO4 + 2HBr = H2TeO3 + H2O + Br2), the bromine being passed into potassium iodide, and the iodine estimated by standard thiosulphate (Gooch and Rowland, Amer. Jour. Sci. [3] XLVIII, 375); (2) by the reducing action of strong hydrochloric acid upon soluble tellurates, chlorine being set free and passed into potassium iodide with libera- tion of iodine, as above; (3) by the action of standard potassium iodide solution upon a solution of tellurous acid containing twenty-five per cent, by volume of strong sulphuric acid, (H2TeO3 + 4H2SO4 + 4KI = TeI4 + 4KHSO4 + 3H2O), tellurous iodide being precipitated as a black, curdy mass, which, when shaken, separates in such a manner that the point when precipitation ceases can easily be detected ; the quantity of tellurium present is calculable from the quantity of potassium iodide used (Gooch and Morgan, Amer. Jour. Sci. [4] n, 271); (4) by the oxidation of tellu- rous acid by means of standard potassium permanganate in acid or alkaline solution (Norris and Fay, Amer. Chem. Jour, xx, 278; Gooch and Peters, Amer. Jour. Sci. [4] viii, 122).
Separation.* From the elements not easily reduced from their compounds to elementary form, tellurium may be separated in general by the action of sulphur dioxide in faintly acid solution ; this precipitates elementary tellurium. From bismuth tellurium is separated by the action of potassium sulphide upon the precipitate thrown down from solutions by hydrogen sulphide, — the tellurium dis-
* See Gutbier, Studien iiber das Tellur.
112 THE RARER ELEMENTS.
solving. From antimony the separation may be accom- plished (i) by hydrazine hydrate, the tellurium being pre- cipitated (Gutbier, Zeitsch. anorg. Chem. xxxn, 260); (2) by treatment of a solution of sulpho-tellurite and sul- pho-antimonite with 20% hydrochloric acid in the pres- ence of tartaric acid, the tellurium separating out (Muth- mann and Schroder, Zeitsch. anorg. Chem. xiv, 433). From silver tellurium is separated by hydrochloric acid, the silver being precipitated; from gold by the action of heat on the two metals, tellurium being volatilized; from mer- cury by the action of phosphorus acid upon a cold dilute hydrochloric acid solution of the salts, mercurous chloride being precipitated.
From selenium tellurium may be separated (i) by hydroxylamme in strong hydrochloric acid solution, the selenium being precipitated (Jannasch and Miiller, Ber. Dtsch. chem. Ges. xxxi, 2388) ; (2) by sulphur dioxide in strong hydrochloric acid solution, selenium being pre- cipitated (Keller, Jour. Amer. Chem. Soc. xix, 771, and xxn, 241); (3) by fusion of the elements with potassium cyanide in the presence of hydrogen, tellurium being pre- cipitated when air is passed through a solution of the melt ;
(4) by the action of ferrous sulphate (vid. Experiment 109) ;
(5) by "the greater volatility of the bromide of selenium (Gooch and Peirce, Amer. Jour. Sci. [4] i, 181).
EXPERIMENTAL WORK ON TELLURIUM.
Experiment 109. Extraction of tellurium from flue-dust, or from waste products from the electrolytic refining of copper. Treat about logrm. of the material with strong commercial hydrochloric acid until nothing further dissolves, and filter. To a small portion of the filtrate add ferrous sulphate, and warm gently. The presence of selenium will be indicated by a reddish precipitate. If selenium has thus been shown to
EXPERIMENTAL WORK ON TELLURIUM. 1*3
be present, take about 5 cm.3 of the original filtrate, precipi- tate the selenium and tellurium by acid sodium sulphite or by magnesium, wash this precipitate, return it to the remainder of the filtrate, and heat to boiling. The selenium present will be precipitated by the tellurium. Remove the selen- ium by filtration and set it aside for later use (vid. Experi- ment 119). From the filtrate precipitate the tellurium by acid sodium sulphite or by magnesium (Crane, Amer. Chem. Jour, xxxin, 408).
Experiment no. Action of strong sulphuric acid upon tellurium. To a small amount of elementary tellurium add a few cm.3 of strong sulphuric acid and warm. Note the reddish- violet color. This reaction constitutes a good test for tellurium.
Experiment 1 1 1 . Preparation of tellurium dioxide, (TeO2) . To a small amount of elementary tellurium add nitric acid, evaporate to dryness, and heat gently.
Experiment 112. Formation of an alkali tellurite,
i
(R2TeO3). Dissolve a little tellurium dioxide in a solution of sodium or potassium hydroxide.
Experiment 113. Formation of telluric acid, (H2TeO4). To a solution of an alkali tellurite add sulphuric acid until the precipitate first formed dissolves. Then add gradually a solution of potassium permanganate until no further bleaching action is noticed.
Experiment 114. Reduction of telluric acid. To a solu- tion of telluric acid prepared in the previous experiment add a little potassium bromide and sulphuric acid, and boil. Note the evolution of bromine and the reduction to tellu- rous acid.
Experiment 115. Precipitation of tellurous iodide, (TeI4). To a solution of an alkali tellurite add sulphuric acid until the precipitate first formed dissolves. Then add a few drops of a solution of potassium iodide. Note the black precipitate.
H4 THE RARER ELEMENTS.
Experiment 116. Precipitation of elementary tellurium. Try the action of the following reducing agents upon sepa- rate portions of an acid solution containing tellurium: stannous chloride, hydrogen sulphide,* sulphurous acid, magnesium, and acid sodium sulphite (vid. Experiment 109).
Experiment 117. Action of tellurium compounds before the blowpipe. Heat on charcoal a small amount of a tellu- rium compound. Note the white sublimate and the green color imparted to the reducing flame.
Experiment 118. Negative test of tellurium. Try the action of ferrous sulphate upon an acidified solution of a tellurite.
SELENIUM, Se, 79.1.
Discovery. For some time previous to the discovery of selenium a red deposit had been noticed in the lead chambers used in the manufacture of sulphuric acid at Gripsholm in Sweden. The deposit was present when the sulphur employed had been prepared from pyrites from Fahlun, Sweden, but was seldom observed when the sulphur had been obtained from other sources. At first the un- known substance was supposed to be sulphur. When it was burned, an odor as of decayed cabbage was given off, and this was supposed to be caused by the presence of tellurium sulphide, although no tellurium could be ex- tracted from the material. In 1817 Berzelius, having become a shareholder in the acid works, examined the red deposit, and in a short time he announced the dis- covery of a new element. Because of its frequent associa- tion with tellurium, and its many points of similarity to that element, he named it Selenium, from aehrjvrf, the moon (Annal. der Phys. u. Chem. (1818) xxix, 229).
* Some authors give TeS2 as the constitution of the precipitate by hy- drogen sulphide.
SELENIUM.
Occurrence. Selenium is found usually in combina- tion with the metals, as in the following minerals:
Clausthalite, PbSe, Tiemannite, HgSe, Guana juatite, Bi2Se3, Naumannite, (Ag2,Pb)Se, Berzelianite, Cu2Se, Lehrbachite, PbSe - HgSe, Eucairite, Cu2Se-Ag2Se, Zorgite, vid. Clausthalite, Crookesite, (Cu,Tl,Ag)2Se, Onofrite, Hg(S,Se), Galenobismutite, PbBi2S4, Durdenite, Fe2(TeO3)3-4H2O, Chalcomenite, CuSeO3 • 2H20, Tellurium (native), Te, Selen-sulphur, #Se-;yS, Selen-tellurium, 3Te-2Se,
contains 27-28% Se
" 25-29% "
" 24-34% "
" 27-30% ••
" 39-40% "
" 24-28% "
" 31-32% "
29-34% "
" .' 30-33% "
" 4- 6% "
" 0-14% "
" i- 2%SeO,
" 48-49% "
" 6- 7%Se
" 35-66% "
" 29-30% "
Extraction. Selenium salts may be extracted from flue- dust by the following methods:
(1) The soluble, material is dissolved by treatment with water, and the selenium is extracted from the residue by aqua regia (Berzelius, vid. Experiment 119).
(2) The seleniferous material is digested with a solu- tion of potassium cyanide at a temperature of 8o°-ioo° C. until the red color has changed to gray, (KSeCN). The selenium goes into solution and may be precipitated by hydrochloric acid (Pettersson, Ber. Dtsch. chem. Ges.
vii, 1719)-
(3) The flue-dust or mineral is fused with sodium car- bonate, and the selenium is extracted with water as sodium selenide and selenite, (Na2Se; Na2SeO3).
Ii6 THE RARER ELEMENTS.
The Element. A. Preparation. Selenium in the ele- mentary condition may be prepared by the action (i) of sulphur dioxide, zinc, or iron, upon selenious acid (Ber- zelius) ; (2) of hydrochloric acid upon sodium seleno-sul- phite (Pettersson) ; (3) of potassium iodide, sodium thio- sulphate, etc., upon selenious acid.
B. Properties. Like sulphur, selenium is known in several allotropic modifications,* and may be either soluble or insoluble in carbon disulphide. In soluble form selen- ium is a red powder which softens at 5o°-6o° C., is partly fluid at 100° C. and is completely fused at 250° C . After it has been melted it remains in a plastic condition for a long time and has a metallic luster. Its specific gravity is 4.2 to 4.3. From a warm solution in carbon disulphide the element separates in red, monoclinic, crystalline plates, and from a cold solution in orange-red monoclinic crys- tals of different type. The specific gravity of these crys- talline varieties is 4.4 to 4.5. Selenium insoluble in carbon disulphide may be obtained by allowing the element to cool very slowly after it has been heated to a higher tem- perature than 130° C., or by allowing the oxygen of the air to act upon selenides in aqueous solution. Under these conditions the element assumes the so-called metallic form, crystallizes in steel-gray hexagonal crystals, and becomes isomorphous with tellurium. Metallic selenium melts at 217° C. without previous softening. Its specific gravity is 4.8.
Selenium boils at 700° C., yielding a dark-yellow vapor which, when condensed and cooled, assumes a form similar to flowers of sulphur; this is called flowers of selenium. The element is soluble in sulphuric acid, giving a green solu- tion, and is oxidized by nitric acid to selenious acid, (H2SeO3) .
* For a recent discussion of these modifications see Saunders, Jour. Phys. Chem. (1900) iv, 423.
SELENIUM. 117
It combines with metals to form selenides. When heated in air or oxygen* it burns with a blue flame and goes over to the dioxide, (SeO2). It is a poor conductor of heat and electricity.
Compounds. A. Typical forms. The following com- pounds of selenium may be considered typical:
Oxides SeO2 SeO8
Chlorides Se2Cl2 SeCl4
SeCl3Br
Oxychloride SeOCl,
Bromides Se2Br2 SeBr4
SeClBr,
Iodides Se2I2 SeI4
Seleno-sulphite SeSO,
Alums RjAl2(SeO4)4 + 24H2O
Thioselenic acid. . . H2SSeO3
Thioseleniate K2SSeOs
Cyanides (CN)2Se
(CN)2Ses
H(CN)Se
K(CN)Se
R(CN)Se2
Nitride N2Se
Phosphides P4Se3
Selenides H2Se
NiSe
Ag2Se
K2Se, etc. Acids (selenious and selenic) HljSeOj H2SeO4
Salts (selenites and seleniates) R^SeOg R2SeO4
B. Characteristics. The compounds of selenium closely resemble those of tellurium, both in structure and in behavior
n8 THE RARER ELEMENTS.
toward reagents. They are, however, rather more sensi- tive to the act 'on of reducing agents, and readily precipitate the red, amorphous variety of the element, which tends to become black when heated. Hydrogen selenide is a gas
which acts like hydrogen sulphide and hydrogen telluride,
i and precipitates the selenides (R2Se). By the treatment
of elementary selenium with nitric acid or aqua regia and evaporation to dryness, selenious oxide, (Se02), is formed, which dissolves in water, forming selenious acid,, (H2SeO3). By the action of powerful oxidizing agents, such as chlorine, bromine, or potassium permanganate , selenious acid may be oxidized to selenic acid, (H2SeO4),
which is not reduced by sulphur dioxide. These acids
i i
form salts of the types R2SeO3 and R2SeO4. By the action
of reducing agents, such as sulphur dioxide or ferrous sulphate, red amorphous selenium may be readily pre- cipitated from selenious acid. Two chlorides, (Se2Cl2; SeCl4), and the corresponding bromides and iodides are known. When selenium is heated, a characteristic, pene-' trating odor is given off which has been variously described as like that of garlic, decayed cabbage, and putrid horse- radish. This odor is caused by the formation of small amounts of the hydride.
Estimation. A. Gravimetric. Selenium is generally weighed as the element, obtained by treating solutions of its compounds (i) with sulphurous acid in hydrochloric acid solution; (2) with potassium iodide in acid solution (Peirce, Amer. Jour. Sci. [4] i, 416); (3) with hypophos- phorus acid in alkaline solution (Gutbier and Rohn, Zeitsch. anorg. Chem. xxxiv, 448). Other reducing agents may be used.
B. Volumetric. Selenium may be determined volu- metrically (i) by oxidizing selenious acid to selenic by means of standard potassium permanganate in sulphuric acid solution, using an excess of permanganate, and titrat-
SELENIUM. 119
ing back with oxalic acid (Gooch and demons, Amer. Jour. Sci. [3] L, 51) ; (2) by reducing selenic or selenious acid by means of potas ium iodide in hydrochloric acid solution,
and determining by appropriate means the iodine set free (Muthmann and Schaefer, Ber. Dtsch. chem. Ges. xxvi, 1008; Gooch and Reynolds, Amer. Jour. Sci. [3] L, 254); (3) by reducing selenic acid to selenious by boiling with hydrochloric acid, (SeO3 + 2HCl = SeO2 + H2O + Cl2), then passing the free chlorine into potassium iodide, and deter- mining the iodine set free (Gooch and Evans, Amer. Jour. Sci. [3] L, 400) ; (4) by employing potassium bromide and sulphuric acid instead of hydrochloric acid in (3) (Gooch and Scoville, Amer. Jour. Sci. [3] L, 402) ; (5) by boiling a solution of selenious acid with sulphuric acid, a known amount of potassium iodide, and an excess of arsenic acid; the reduction of the selenious acid will decrease the reduction of arsenic acid; the quantity of arsenious acid present at the close of the action may be measured, after neutral- ization with potassium bicarbonate, by standard iodine (Gooch and Peirce, Amer. Jour. Sci. [4] i, 31); (6) by the reduction of selenious acid to elementary selenium by means of standard sodium thiosulphate solution in excess in the presence of hydrochloric acid, — the excess of thio- sulphate being determined by standard iodine solution (Norris and Fay, Amer. Chem. Jour, xvm, 703 ; Norton, Amer. Jour. Sci. [4] vn, 287) ; (7) by boiling elementary selenium with ammonia and standard silver nitrate solution, acidifying with nitric acid, and determining the excess of silver nitrate by ammonium sulpho-cyanide, with ferric alum as indicator; the quantity of selenium present is calculable from the quantity of silver nitrate used, as is shown in the following equation: 4AgNO3 + 3Se + 3H2O = 2Ag2Se + H2SeO3 + 4HNO3 (Friedrich, Zeitsch. angew. Chem. xv, 852).
120 THE RARER ELEMENTS.
Separation. Selenium is separated, together with tel- lurium, from other elements by methods given under Tellurium. Methods of accomplishing the separation of these two elements from each other have also been de- scribed.
EXPERIMENTAL WORK ON SELENIUM.
Experiment 119. Extraction of selenium from (i) flue- dust and (2) seleniferous residues from the electrolytic refining of copper, (i) Treat about 25 grm. of the washed flue- dust with aqua regia as long as any evidence of action is observed, and evaporate to dryness. Extract the residue with about 25 cm.3 of strong common hydrochloric acid, and filter. To the filtrate add about a gram of dry ferrous sulphate, and warm gently if necessary. Filter off the red amorphous selenium.
(2) To free the selenium obtained in Experiment 109 from the excess of tellurium present (a) treat the material with hydrochloric acid and either a little chlorine or a drop of nitric acid. Precipitate the selenium by ferrous sulphate. (6) Or warm the material with a dilute solution of potassium cyanide. The selenium goes into solution as potassium seleno-cyanide and may be precipitated by acidifying the solution with hydrochloric acid.
Experiment 120. Preparation of selenium dioxide, (SeO2). To a small amount of elementary selenium add nitric acid until the oxidation is shown to be complete by the cessation of the evolution of red fumes (oxides of nitrogen). Evaporate to dryness and warm gently. The white residue is selenium dioxide. Dissolve this in a little water to form selenious acid, (H2SeO3).
Experiment 121. Precipitation of barium selenite, (BaSeO3). To a little selenious acid add a few drops of
EXPERIMENTAL WORK ON SELENIUM. 121
a barium salt in solution. Test the action of hydro- chloric acid upon the precipitate.
Experiment 122. Formation of selenic acid, (H2SeOJ. To a few cm.3 of selenious ac d add first a small amount of sulphuric acid and then a solution of potassium per- manganate until the purple color is permanent. Bleach by the careful addition of oxalic acid.
Experiment 123. Reduction of selenic acid to selenious. Add to a given volume of selenic acid half as much strong hydrochloric acid and boil to about two thirds of the total volume. Note the evolution of chlorine. Test by starch iodide paper.
Experiment 124. Precipitation of elementary selenium. Try the action of the following reducing agents upon dilute selenious acid: sulphur dioxide, hydrogen sulphide, acid sodium sulphite, potassium iodide, stannous chloride, ferrous sulphate.
Experiment 125. Solvent action of carbon disulphide upon selenium. To a little dry, washed, amorphous selen- ium add carbon disulphide. Filter, and allow the filtrate to evaporate.
Experiment 126. Solvent action of potassium cyanide upon selenium. To a small amount of the red amorphous selenium add a few cm.3 of a dilute solution of potassium cyanide (poison!), warm gently, and filter. To the filtrate add hydrochloric acid.
Experiment 127. Behavior of selenium when subjected to heat. Heat a small amount of elementary selenium on a glass rod. Note the odor, and the color of the flame.
Experiment 128. Action of strong sulphuric acid upon selenium. To a small amount of elementary selenium add a few cm.3 of strong sulphuric acid and warm. Note the color. Compare with tellurium (vid. Experiment no).
122 THE RARER ELEMENTS.
PLATINUM, Pt, 194.8.
Discovery. In the year 1750 William Watson presented to the Royal Society a communication from William Brownrigg in which was described a " semi-metal called Platina di Pinto ' ' found in the Spanish West Indies. Wat- son stated that, so far as he knew, no previous mention had been made of this substance except by Don Antonio de Ulloa in the history of his voyage to South America, pub- lished in Madrid in 1748 (Phil. Trans. Roy. Soc. (1750) XLVI, 584). However, an earlier discovery is suggested by a statement of Scaliger in 1558, who, in combating the opinion of Cardanus, that all metals are fusible, declared that an infusible metallic substance existed in the mines of Mexico and Darien. As platinum is found in those coun- tries, it is probably the metal referred to The name Platinum is derived from the Spanish platina, the diminu- tive of plata, silver.
Occurrence. Platinum occurs alloyed with the various metals of its group — palladium, osmium, iridium, etc. — and associated with other metals, as iron, lead, copper, titanic iron, etc. It is found chiefly in the Ural Mountains, but also in Brazil, Mexico, Borneo, California, North Carolina, and elsewhere. It comprises from fifty to eighty per cent, of the alloys in which it occurs. Platinum is found com- bined in the mineral sperrylite, PtAs2, which contains about fifty-three per cent, of the metal.
Extraction. Platinum may be extracted from its alloys by the following methods:
(i) Fusion process. The material is fused with sul- phide of lead. The iron present combines with the sul- phur. The platinum alloys with the lead, while the os- mium and iridium do not. The lead-platinum alloy is separated from the mass and cupelled. The platinum is left (Deville and Debray).
PLATINUM. 123
(2) Wet process. The pulverized alloy is heated in a porcelain dish with aqua regia as long as action continues. The solution obtained is nearly neutralized with calcium hydroxide, and the iron, copper, rhodium, iridium, and part of the palladium separate. After the removal of these, the nitrate is evaporated to dryness and the residue is ignited and treated with water and hydrochloric acid. The plati- num, with traces of the platinum metals, remains.
The Element. A. Preparation. As extracted from its alloys, platinum is in the elementary condition (vid. Ex- traction).
B. Properties. In its usual form, elementary platinum is a grayish-white metal which is very malleable and ductile, but fusible only in the oxy hydrogen blowpipe or by means of the electric current. At no temperature is it oxidized by water or oxygen, or attacked by the simple acids. It is soluble, however, in aqua regia. Platinum is not acted upon by sulphur alone, but if alkalies are present with the sulphur some action takes place. It is attacked also when heated with potassium nitrate. Its specific gravity is 21.48.
Besides the ordinary form, the element platinum is known to exist in two allotropic conditions: (i) spongy platinum, obtained by the- ignition of ammonium chloro- platinate, and (2) platinum-black, obtained by reducing acid solutions of platinum salts. In both of these forms platinum condenses gases on its surface.
Compounds. A. Typical forms. The following may be regarded as typical compounds of platinum :
Oxides PtO Pt3O4 PtO2 v
Chlorides PtCl2 PtCl4
Double chlorides PtCl2-SrCl2+ PtCl4 • 2AgCl, etc.
6H2O, etc.
Bromides PtBr2 PtBr4
Double bromides PtBr2-2KBr, etc. PtBr4 • SrBr2-f ioH2O
Iodides PtI2 PtI4
124 THE RARER ELEMENTS.
Double iodides PtI4 • 2KI, etc.
Fluorides PtF3 PtF4
Sulphides PtS * PtS2
Oxysulphide PtOS
Sulpho salts R2PtS6
Sulphites PtSO3 • R2SO3 ; PtSO3 • 2RC1
Nitrites R2(NO2)4Pt
lodonitrites R2(NO2)2I2Pt
Cyanide Pt(CN)a
Hydro - platino - cyanic
acid H2Pt(CN)4
Platino-cyanides R2Pt(CN)4; RPt(CN)4, typical
Chloroplatinic acid. . . . H2PtCl<,
Chloroplatinates RaPtCl,,; RPtCl., typical
B. Characteristics. The compounds of platinum may be divided into two classes, of which the platinous and platinic oxides, (PtO; PtO2), serve as types. The salts of the lower condition of oxidation are usually colorless or reddish brown; they give with hydrogen sulphide or am- monium sulphide a dark-brown precipitate of platinous sulphide, (PtS), which is soluble in ammonium sulphide. They are decomposed at red heat, and are slowly reduced to metallic platinum when boiled with ferrous sulphate. The salts of the higher condition of oxidation have a yellow or brown color, and like the platinous salts they are de- composed at red heat. Metals in general and organic matter precipitate platinum from solutions of platinic salts. The brownish-gray platinic sulphide, (PtS2), is pre- cipitated by the action of hydrogen sulphide upon a solu- tion of chloroplatinic acid, (H2PtCl6) ; this sulphide dissolves slowly in ammonium sulphide. Salts of potassium and ammonium act upon chloroplatinic acid precipitating the
corresponding salts of that acid, (R2PtCl6) . When platinous chloride dissolves in potassium cyanide, platinum potas-
PLATINUM. 125
sium cyanide is formed, (K2Pt(CN)4 + 4H2O). Many salts
of this type are known.
The platinum-ammonium compounds comprise a large
number of complex salts of the following types:
(a) The platosamines, PtR2(NH3)4; PtR2(NH3)3;
PtRjCNHjV, PtR2(NH3); and (6) the platinamines,
PtR4(NH3)4; PtR4(NH3)3; PtR4(NH3)2; PtR4(NH3).
In the above formulae R may stand for OH, Cl, Br, I,
or NO3. These compounds are formed by the action of ammonia upon the platinum salts.
Potassium iodide gives a red-brown color to very dilute solutions of platinum salts.
Estimation. A. Gravimetric. Platinum is generally weighed as the metal, obtained (i) by precipitation from solutions of compounds by means of appropriate reducing agents, such as formic acid, alcohol in alkaline solution, or magnesium (Atterberg, Chem. Ztg. xxn, 538) ; (2) by pre- cipitation of the sulphide and ignition; (3) by precipitation of ammonium or potassium chloroplatinate, and decomposi- tion by heat into the metal and the volatile or soluble alkali chloride.
B. Volumetric. Platinum may be estimated volumet- rically by reducing the tetrachloride by means of potas- sium iodide, (PtCl4 + 4KI=PtI2 + I2 + 4KCl)> and determin- ing by standard sodium thiosulphate the iodine thus liber- ated (Peterson, Zeitsch. anorg. Chem. xix, 59).
Separation. , From most other elements platinum may be separated by the action of reducing agents in precipitat- ing the metal from solutions. From the metals with which it is most often found associated it may be separated by the following methods: from gold (i) by the action of ammonium chloride upon the chlorides, ammonium chloro- platinate being precipitated; (2) by the action of hydro- gen dioxide and sodium hydroxide upon cold solutions, the gold being precipitated (Vanino and Seeman, Ber. Dtsch.
126 THE RARER ELEMENTS.
chem. Ges. xxxn, 1968) ; (3) by the action of oxalic acid or ferrous salts, gold being again precipitated (Hoffmann and Kriiss, Zeitsch. anal. Chem. xxvu, 66; Bettel, Chem. News LVI, 133) ; from silver by heating the metals with concen- trated sulphuric acid, silver dissolving (Richards, The Analyst, xxvu, 265) ; from mercury by ignition of the metals, mercury being volatilized.
The separation of platinum from the other platinum metals is so involved with the separation of these from each other that the whole subject will be briefly considered in this place. The following methods have been suggested, (i) The ore is first treated with chlorine water, which ex- tracts the gold, then with dilute aqua regia, which dis- solves the platinum, palladium, and rhodium. From this solution the platinum is precipitated by ammonium chloride and alcohol; and from the filtrate, after neutralization with sodium carbonate, the palladium is precipitated as the cyanide by mercury cyanide. The residue from the aqua regia treatment, containing osmium, iridium, and ruthe- nium, is heated in air. Osmium is volatilized as the tetrox- ide, ruthenium sublimes as the dioxide, and iridium is left (Pirngniber, J. B. (1888), 2560; Wyatt, Eng. and Min. J. XLIV, 273). (2) A neutral or acid solution of the plat- inum metals, gold, and mercury, containing chlorine, is treated with dilute nitric acid and heated to boiling in a retort ; osmic tetroxide distils. The solution is cooled, and shaken with ether, which withdraws the chloride of gold. After the removal of the ether and gold by means of a separating funnel the remaining solution is treated with ammonium acetate and boiled with formic acid. This treatment precipitates all the metals, which are then heated in a current of hydrogen to volatilize the mercury. The remaining metals are mixed with sodium chloride and heated with moist chlorine, and the mass is extracted with water. If there is any residue at this point it will probably
PLATINUM. 127
be found to be indium, and ruthenium. The solution is treated with concentrated ammonium chloride as long as any precipitate forms. This precipitate consists of the double chlorides of ammonium with platinum, iridium, and ruthenium respectively, palladium and rhodium remaining in solution. The precipitate is dissolved in warm water and treated with hydroxylamine, which reduces the irid- ium and ruthenium to the condition of the sesquichlorides ; upon the addition of ammonium chloride platinum is pre- cipitated as the chloroplatinate. The hydroxylamine fil- trate is evaporated, the residue is heated in the presence of hydrogen and fused with potassium hydroxide and nitrate, the mass is cooled and extracted with water. Ruthenium dissolves as potassium ruthenate, (K2RuO4), and iridium remains as the hydrate, (Ir(OH)3). The solution contain- ing rhodium and palladium is evaporated slowly to dryness in the presence of an excess of ammonia, and the residue is dissolved in the smallest possible amount of a warm, dilute ammoniacal solution. Upon cooling, the rhodium separates as a complex chloride, (Rh(NH3)5Cl3), and the palladium remains in solution (Mylius and Dietz, Ber. Dtsch. chem. Ges. xxxi, 3187). (3) Gold is removed by means of dilute aqua regia. By treatment with concentrated aqua regia platinum, palladium, rhodium, ruthenium, and part of the iridium are then dissolved, while an insoluble alloy of os- mium and iridium in the form of grains or plates remains. This alloy is mixed with sodium chloride and the mixture is heated in a tube with chlorine. Osmium tetroxide, (OsO4), distils, and sodium-iridium chloride, (Na2IrCl6), re- mains (Wohler, Pogg. Annal. xxxi, 161). To the solution of the other platinum metals in aqua regia ammonium chloride. is added. The precipitate, consisting of the double salts of platinum and iridium, may by ignition be converted intq iridium-bearing platinum sponge (used in the manufacture of platinum vessels) . To the filtrate iron or copper is added,
128 THE RARER 'ELEMENTS.
which throws down .the palladium, rtiodium, and ruthenium as a metallic powder. From this mixture palladium and the iron or copper are dissolved by nitric acid, and the solu- tion is then shaken with mercury, which- removes the palla- dium (von Schneider, Liebig Annal. v, 264, suppl.). The mixture of rhodium and ruthenium remaining is heated with sodium chloride at low redness in a current of chlorine and the mass is extracted with water. This liquid is boiled with potassium nitrite and "enough potassium carbonate to make the solution faintly alkaline. It is then evaporated to dryness and the residue is pulverized and extracted with absolute alcohol. The rhodium remains undissolved as a double nitrite of potassium and rhodium, (K6Rh2(NO2)12, while the ruthenium dissolves, also as a double nitrite with potassium, (Ru(NO2)6-6KNO2).
Platinum may be separated from palladium (i) by the action of warm dilute nitric acid upon the metals, palladium dissolving; (2) by the action of a strong solution of am- monium chloride and alcohol upon the double potassium salts, the palladium salt being soluble (Cohn and Fleissner, Ber. Dtsch. chem. Ges. xxix, R. 876); from iridium (i) by electrolysis, the platinum being precipitated (Smith, Amer. Chem. Jour, xiv, 435) ; (2) by the action of potassium nitrite, sodium carbonate, and boiling water upon the double potassium salts, iridium being reduced to the con- dition of the sesquichloride and dissolved (Gibbs, Amer. Jour. Sci. [2] xxxiv, 347) ; from osmium by heating in the presence of oxidizing material, osmium tetroxide being formed and volatilized ; from ruthenium by treating potas- sium chloroplatinate and the corresponding ruthenium salt with cold water > ;the ruthenium salt dissolving (Gibbs, loc. tit.)', from rhodium (i) by the method described for the separation from ruthenium; or (2) by the action of concentrated solutions* of the alkali chlorides upon these salts, the rhodium dissolving (Gibbs, loc. tit.).
EXPERIMENTAL WORK ON PLATINUM. 129
<
EXPERIMENTAL WORK ON. PLATINUM.
Experiment 129. Preparation of chloroplatinic acid from laboratory residues. • Boil the residues consisting of po- tassium chloroplatinate, etc., with a solution of sodium carbonate and add a little alcohol. The platinum is de- posited as a black powder. Wash the powder, first with hot wrater, then with hot hydrochloric acid; dry it, dis- solve it in aqua regia, evaporate the liquid, adding a little hydrochloric acid from time to time to remove the nitric acid, until the point of crystallization is reached.
Experiment 130. Precipitation of the chloroplatinates of ammonium, potassium, ccssium, rubidium, and thallium,
(R2PtCl6). To separate portions of a solution of chloro- platinic acid add salts of ammonium, potassium, caesium, rubidium, and -thallium in solution. Note the compara- tive insolubility of the new compounds in water and in alcohol.
Experiment 131. Precipitation of platinic sulphide, (PtS2). To a solution of chloroplatinic acid add a little hydrogen sulphide, and warm.
Experiment 132. Precipitation of elementary platinum, (a) To a solution of a platinum salt add sodium carbonate to alkaline reaction; add also a few drops of alcohol and boil.
(6) Try the action of oxalic acid upon a platinum salt in solution.
Experiment 133. Action of acids upon platinum. Try separately the action of strong hydrochloric and nitric acids upon metallic platinum. Note the effect of a mixture of the two acids upon the metal.
Experiment 134. Test for platinum in solution. To a very dilute solution of a platinum sarlt free from chlorine add a small crystal of potassium iodide. Note the color.
13° THE RARER ELEMENTS.
THE PLATINUM METALS
OTHER THAN PLATINUM.
Occurring almost invariably associated with platinum and usually alloyed with it are small quantities of certain rare elements which, together with platinum, comprise the group of so-called Platinum Metals. These very rare elements are the following:
Palladium, Pd, 106 Osmium, Os, 191
Iridium, Ir, 193 Rhodium, Rh, 103
Ruthenium, Ru, 101.7
Discovery. In 1803, in the course of the purification of a considerable quantity of crude platinum, Wollaston isolated a new metal which he named Palladium, in honor of the discovery by Olbers of the planetoid Pallas. The newly discovered element was brought to the attention of scien- tists anonymously through a dealer's advertisement, which offered "palladium or new silver" for sale. Much dis- cussion as to the nature of the substance ensued, Chenevix, in particular, holding it to be an alloy of platinum and mer- cury. In 1805 Wollaston confessed to the discovery and naming of the metal (Phil. Trans. Roy. Soc. (1803) xcm, 290; ibid. (1805) xcv, 316; Nicholson 's J. (1805) x, 204).
The same year that palladium was discovered, Smithson Tennant found that ' * the black powder which remained after the solution of platina did not, as- was generally believed, consist chiefly of plumbago, but contained some unknown metallic ingredients. " In 1 804 he presented to the Royal Society as the result of his study a communication announc- ing the discovery of two new metals, -Iridium, named ' * from the striking variety of colors which it gives while dissolving in marine acid, ' ' and Osmium, so called because of the
THE PLATINUM METALS. 131
penetrating odor (007*77, odor) of the acid obtained from the oxidation of the element when it is heated in a finely divided condition (Phil. Trans. Roy. Soc. (1804) xciv, 411).
A few days after Tennant's communication, Wollaston announced the discovery of an element in the * ' fluid which remains after the precipitation of platina by sal ammoniac, ' * and suggested the name Rhodium (podios, rose-like), "from the rose color of a dilute solution of the salts containing it" (Phil. Trans. Roy. Soc. (1804) xciv, 419).
In 1826 Osann claimed the discovery of three new ele- ments in platinum alloys. These he named Ruthenium, Polinium, and Pluranium (Pogg. Annal. vm, 505; Amer. Jour. Sci. xvi, 384). Later he withdrew the claim. In 1844 Claus found that there was an unknown metal in the mixture of substances which had been called by Osann "ruthenium oxide," and for it he retained the name ruthenium, derived from Ruthenia, i.e. Russia, where the substance was first found (Pogg. Annal. LXIV, 192, 208; Amer. Jour. Sci. XLVIII, 401).
Occurrence. The very rare platinum metals, as has been already stated, are found in general in platinum- bearing material. Palladium and iridium sometimes occur native; the others always in alloys or in combination.
% Ru Native platinum contains 0.1-3.1 traces-4 . 2 traces o . 2-3 . 4
" iridium Palladium gold Iridosmine Laurite,
Rhodium gold
0.4-0.8 27-76.8 circa 7
5-10
17-48 40.7 0.5-12.3 0.2-6
circa 3 65
34-43
Extraction. For methods of extraction of the very rare platinum metals see Extraction and Separation of Platinum.
The Elements. I. PALLADIUM. A. Preparation. Ele- mentary palladium may be obtained (i) by heating the potassium double chloride with hydrogen (Roessler) ; (2) by
132 THE RARER ELEMENTS.
heating the iodide with hydrogen; and (3) by heating the chloride or cyanide.
B. Properties. Palladium is a ductile, malleable, white metal which looks like platinum. It may be partially oxidized before the , oxy hydrogen blowpipe. It is soluble in strong nitric, hydrochloric, and sulphuric acids, and easily soluble in aqua regia. It fuses at a lower temperature than any other of the platinum metals. In spongy form it has the power of absorbing gases. Its specific gravity is 11.4-11.8. Because of the color and hardness of pal- ladium and its unalterability in the air it is used for the graduated surfaces of fine astronomical instruments. It may be distinguished from the other platinum metals by the comparative ease with which it dissolves in nitric acid.
II. OSMIUM. A. Preparation. The element osmium may be prepared (i) by heating the amalgam in the presence of hydrogen (Berzelius) ; (2) by heating the sulphide in a closed coke crucible ; (3) by passing the vapor of the tetroxide mixed with carbon dioxide and carbon monoxide through a heated porcelain tube; (4) by passing the vapor of the tetroxide through a heated porcelain tube containing finely divided carbon (Deville and Debray); (5) by igniting osmyldiamine chloride, (Os(NH3)402Cl2), in a current of hydrogen.
B. Properties. Osmium, the heaviest of the platinum metals, is a bluish substance, crystals of which are harder than glass. In the compact form it is insoluble in all acids and in aqua regia, and is rendered soluble only by fusion with nitrates. The amorphous modification is slowly soluble in nitric acid and in aqua regia. The specific gravity of the compact and amorphous modifications is 21.3; of the crystalline form 22.4. In the alloy iridosmine the element is employed for compass bearings and for the tips of gold pens.
III. IRIDIUM. A. Preparation. Metallic iridium may
THE PLATINUM METALS. 133
be obtained (i) by heating iridium-ammonium chloride, and (2) by heating indium-potassium chloride with sodium carbonate.
B. Properties. Iridium, a hard, brittle metal, resembles silver and tin in appearance. The ignited form is insoluble in all acids and in aqua regia. The element is partially oxidized, however, by fusion with sodium nitrate, and the fused mass may be dissolved by boiling it with aqua regia. In spongy form iridium has the specific gravity of 15.86; after fusion the specific gravity is 21-22. Elementary iridium is not used in the arts, but its alloy with osmium, as stated above, is employed for compass bearings and for the tips of gold pens; its alloy with platinum is used in the manu- facture of laboratory vessels and for standard weights and measures, and an oxide is used in ehina-painting.
IV. RHODIUM. A. Preparation. Elementary rhodium may be prepared (i) by heating ammonium -rhodium ses- quichloride; (2) by heating rhodium sesquichloride and sodium in a current of hydrogen; (3) by heating rhodium sulphide to a white heat; and (4) by allowing reducing agents, as formic acid, zinc, iron, alcohol in alkaline solu- tion, hydrogen, etc., to act upon soluble salts.
B. Properties. Rhodium is a grayish- white metal which has the appearance of aluminum. When pure it is almost absolutely insoluble in acids and in aqua regia, but when alloyed it may be dissolved in aqua regia. It is fusible before the oxyhydrogen blowpipe, but more difficultly than platinum. It has the property of absorbing hydrogen. Of all the platinum metals rhodium is most easily attacked by chlorine. Its specific gravity is 11-12. The alloy of rhodium with steel is somewhat used in the arts.
V. RUTHENIUM. A. Preparation. The element ruthe- nium may be obtained (i) by heating the oxide with illu- minating-gas, and (2) by heating mthenium-ammonium- mercury chloride.
THE RARER ELEMENTS.
B. Properties. Ruthenium is a hard, brittle metal, dark gray to black in color. It is almost completely insolu- ble in acids and in aqua regia; and osmium alone, of all the platinum metals, is more difficultly fusible. It may be slightly oxidized by fusion with caustic potash and oxidized to a greater degree by fusion with potassium nitrate. The specific gravity of the crystalline form is 12.26; of the melted form 11.4; and of the porous form 8.6.
Compounds. A. Typical forms. The following com- pounds of the platinum metals may be considered typical:
Oxides Pd2O
PdO
Pd02
Chlorides PdCl
PdCl2
PdCl4 Bromides PdBr2
PdBr4 Iodides Pdl,
|
OsO |
IrO? |
RhO |
RuO |
|
Os203 |
Ir:03 |
Rh203 |
Ru2O3 |
|
Os02 |
IrO2 |
Rh02 |
RuO2 |
|
(Os03)* |
(Ru03)* |
||
|
OsO4 |
RuO4 |
||
|
(Ru207)* |
|||
|
OsCl2 |
IrCl2 |
RhCl2 |
RuCl3 |
|
OsCl, |
Ir2Cl8 |
Rh2Cl8 |
RuA, |
|
OsCl4 |
IrCl4 |
RuCl, |
|
|
Ir2Br6 |
|||
|
IrBr4 |
Sulphides. .
.Pd2S PdS
PdS,
Sulphates. .... ,PdSO4
Sulphites PdSOj-
3Na2S03
Sulpho salts. . . .R2Pd3S4 R2PdS3
OsS2 OsS4
OsS03
IrI4
IrS
Ir2S,
IrS2
Rh2I8
RhS Rh2S3
Rh2(S04)3
Ir2(S03)8 Rh2(SOs)a
Ru2S3 RuS2 RuS3
* This oxide is known only in combination.
THE PLATINUM METALS.
135
Nitrites Pd(NO2)2- 2KNO2
Nitrates
Pd(NO3)
Ir2(N02)8. Rh2(N02V Ru2(N02)fl. 6HN02 6RNO2 6RNO2
Acids and corre-
spond'g salts.. . H2PdCl4 ;
R2PdCl4
H2PdCl8; R2PdCl0
H.OSC1.;
RsOsCl,, H2OsCl6;
R2OsCle
R4RhCl7; R3RhCl<,
H2RuCl5
R2IrCl«
Characteristics. I. PALLADIUM. The compounds of pal- ladium resemble those of platinum, both in form and in general characteristics. As in the case of platinum, palladium combines with ammonia to form complex salts, and an oxide, (PdO), forms salts with sulphur dioxide and with nitrogen trioxide, (N2O3). In general the salts are quite easily reduced to the metal by heating ; their solutions resemble a solution of platinic chloride in color. Two oxides, (PdO; PdO2), are well known, of which the lower forms the more stable compounds. These compounds give a yellowish-brown precipitate with potassium hydroxide. Solutions of palladium salts give with mercuric cyanide a yellowish- white precipitate, (Pd(CN)2) ; with potassium iodide a black precipitate, (PdI2), which is soluble in excess of the reagent ; and with hydrogen sulphide also a black precipitate, (PdS), insoluble in ammonium sulphide. Mercuric cyanide and potassium iodide are often used as tests for palladium.
II. OSMIUM. Compounds of osmium are known in five degrees of oxidation. The lowest three oxides, (OsO; Os2O3; OsO2), are basic in character, the fourth,* (OsO3), is acidic, and the fifth, (OsO4), is also acidic, but it forms
* Known only in salts.
136 THE RARER ELEMENTS.
no salts. Three chlorides, (OsCl2 ; OsCl3 ; OsCl4) , are known, corresponding to the lowest oxides. The metals sodium,
potassium, and barium form salts of the type R2OsO4. These salts are readily decomposed, especially by acids, and form the dioxide and the tetroxide. When osmium com- pounds are heated in the air with oxidizing agents, or are melted with potassium nitrate, the tetroxide is obtained. It is volatile when heated, highly corrosive, and disagree- able like chlorine. It is soluble in water and is reduced by reducing agents. From potassium iodide it frees iodine, and with formic acid to which potassium hydroxide has been added it gives a violet color. With ferrous sulphate it precipitates black osmium hydroxide, (Os(OH)4), and with hydrogen sulphide it brings down the brownish-black sulphide (OsS4), which is insoluble in ammonium sulphide. III. IRIDIUM. The compounds of iridium exist chiefly in three conditions of oxidation, of which the di-, tri-, and tetrachlorides may serve as types, (IrCl2; Ir2Cl6; IrCl4). The iridium compounds are reduced to the metal when mixed with sodium carbonate and heated in the outer flame of a Bunsen burner. The alkali double chlorides with iridous chloride, (IrCl2), are in general soluble in water. Solutions of iridium salts in the lowest condition of oxida- tion give with potassium hydroxide a greenish precipitate, which tends to darken when boiled. Reducing agents, as sodium formate, precipitate metallic iridium, and hydro- gen sulphide precipitates from the warmed solution a brown iridium sulphide (IrS). By means of oxidizing agents, solutions of iridous salts may be converted into the high- est condition of oxidation. From solutions of this latter type potassium hydroxide throws down a dark-brown pre- cipitate of potassium -iridium chloride, (IrCl4'2KCl), and hydrogen sulphide precipitates slowly a brown sulphide, (Ir2S3). The greater number of iridium compounds are easily reduced by hydrogen on being heated. The pres-
THE PLATINUM METALS. 137
ence of indium may be detected by the blue color de- veloped when the compound is heated with concentrated sulphuric acid to which ammonium nitrate has been added.
IV. RHODIUM. Although three oxides of rhodium are known and described, (RhO; Rh203; RhO2), salts of only two conditions of oxidation are generally found; of these the di- and trichlorides are types, (RhCl2; Rh2Cl6). From solutions of rhodium salts reducing agents precipitate the metal. Hydrogen sulphide throws down from a cold solu- tion the sulphide (Rh2S3), and from a hot solution the sulphydrate (Rh2(SH)6). The insolubility of the double chloride of rhodium and sodium, (Rh2Cl'6NaCl), in water, and of the double nitrate of rhodium and potassium, (K6Rh6(NO2)12), in alcohol is made use of in separating the metal from the other members of the group. Rhodium is detected in the presence of the other platinum metals by the yellow solution obtained after fusion with potassium acid sulphate and the change of color to red upon the ap- plication of hydrochloric acid.
V. RUTHENIUM. In the variety of conditions of oxida- tion in which they are found, the compounds of ruthenium resemble those of osmium. The lowest three oxides are basic in character, (RuO; Ru2O3; RuO2), and form salts of which the three chlorides, (RuCl2 ; Ru2Cl6 ; RuCl4),are typical.
The trioxide, (RuO3), is known only in combination, where
i it acts as an acid and forms salts of the type R2RuO4.
Another oxide, (Ru2O7), known only in combination, forms
i
salts represented by the formula RRuO4. The tetroxide (RuO4) is volatile and similar to the corresponding oxide of osmium in its chemical behavior; it has a characteristic odor. A solution of the trichloride, (Ru2Cl6), throws out, when heated, a dark precipitate which is generally sup- posed to be an oxychloride; this precipitate is held in suspension in the liquid and gives a pronounced coloration,
I38 THE RARER ELEMENTS.
even in very dilute solutions. Hydrogen sulphide, acting upon solutions of ruthenium salts, precipitates a mixture of sulphides, oxysulphides, and sulphur; this mixture is brown or black, and may contain one or more of the sul- phides Ru2S3, RuS2, and RuS3.
Estimation. The platinum metals are weighed in the elementary condition, obtained as described under Prepara- tion of the various metals.
Osmium may be determined volumetrically by causing potassium iodide to act upon the tetroxide in the presence of dilute sulphuric acid, (OsO4 + 4KI + 2H2SO4 = OsO2 + 2K2SO4 + 4l + 2H2O), and estimating by means of sodium thiosulphate the iodine thus liberated (Klobbie,, Chem. Central-Blatt (1898) n, 65 (abstract).,
Separation. The separation of the platinum metals has been considered under Platinum. The following are additional references: Gibbs, Amer, Jour. Sci. [2] xxxi, 63; xxxiv, 341; xxxvn, 57; Forster, Zeitsch. anal. Chem. v, 117; Bunsen, Liebig Annal. CXLVI, 265; Chem. News xxi, 39; Deville and Debray, Compt. rend. LXXXVII, 441; Chem. News xxxvin, 188; Wilm, Ber. Dtsch. chem. Ges. xvi, 1524; Leidie, Compt. rend, cxxxi, 888; Bull. Soc. Chim. d. Paris [3] xxvn, 179.
EXPERIMENTAL WORK ON THE PLATINUM METALS.*
Experiment 135. Precipitation of palladious iodide, (PdI2). To a solution of a palladium salt add a little potassium iodide in solution.
Experiment 136. Precipitation of palladious sulphide i, (PdS). (a) Pass hydrogen sulphide through a solution of a palladious salt.
* For experimental work on platinum see page 129.
EXPERIMENTAL WORK ON THE PLATINUM METALS. 139
(b) Try the action of ammonium sulphide upon a palla- dious salt in solution.
Experiment 137. Precipitation of elementary palladium. To a solution of a palladium salt add sodium carbonate to alkaline reaction; add also a few drops of alcohol and boil.
Experiment 138. Action of nitric acid upon palladium. Try the action of nitric acid upon a small piece of metallic palladium.
Experiment 139. Precipitation of osmium sulphide, (OsS4). (a) To a solution of osmium tetroxide acidified with hydrochloric acid add a little hydrogen sulphide.
(b) Try the action of ammonium sulphide upon the tetroxide in solution.
Experiment 140. Formation of potassium osmate, (K2OsO4). To a solution of osmium tetroxide add a solu- tion of potassium hydroxide. Note the yellow color.
Experiment 141. Action of reducing agents upon osmium tetroxide. Try the action of an alkali sulphite, formic acid, and tannic acid, respectively, upon a solution of osmium tetroxide.
Experiment 142. Action of osmium tetroxide upon hy- driodic acid. To a solution of osmium tetroxide add a little starch paste and a small crystal of potassium iodide. Acid- ify the solution with dilute sulphuric acid. Note the blue color, due to free iodine.
Experiment 143. Precipitation of elementary osmium. (a) To a solution of the tetroxide add stannous chloride.
(b) Try the action of zinc and hydrochloric acid upon a solution of the tetroxide.
Experiment 144. Odor test for osmium. Warm a dilute solution of osmium tetroxide, or warm with nitric acid a solution of any osmium salt of the lower condition of oxidation. Note the odor.
Experiment 145. Precipitation of iridium sulphide,
14° THE RARER ELEMENTS.
(Ir2S3). Pass hydrogen sulphide through a solution of iridium tetrachloride. Try the action of ammonium sul- phide upon the precipitate.
Experiment 146. Formation of the double chlorides of iridium with ammonium and potassium, ((NH4)2IrCl6 and K2IrCl6). To separate portions of a fairly concentrated solution of iridium tetrachloride add ammonium chloride and potassium chloride respectively.
Experiment 147. Reduction of iridium salts, (a) To a solution of iridium tetrachloride add oxalic acid.
(b) Try similarly the action of zinc upon an acid solu- tion of the salt.
Experiment 148. Action of sodium hydroxide upon iridium tetrachloride. Add sodium hydroxide in excess to iridium tetrachloride and warm. Note the change in color. The iridium salt is said to be reduced to the tri- chloride by this treatment. Acidify with hydrochloric acid and add potassium chloride. Note the absence of precipitation.
Experiment 149. Precipitation of rhodium sulphide, (Rh2Ss). Pass hydrogen sulphide through a solution of sodium-rhodium chloride. Try the action of ammonium sulphide upon the sulphide precipitated.
Experiment 150. Reduction of rhodium salts. To an acid solution of a rhodium salt add zinc.
Experiment 151. Formation of the double nitrite of potas- sium and rhodium, (K3Rh(NO2)6). To a solution of sodium- rhodium chloride add potassium nitrite in solution and warm. Try the action of hydrochloric acid upon the precipitate.
Experiment 152. Precipitation of rhodium hydroxide, (Rh(OH)3). Note the first action and the action in excess of sodium or potassium hydroxide upon a solution of sodium- rhodium chloride. Boil the solution just obtained.
Experiment 153. Precipitation of ruthenium sulphide,
GOLD. 141
(Ru2S3). (a) To a solution of ruthenium trichloride add hydrogen sulphide.
(b) Use ammonium sulphide as the precipitant.
Experiment 154. Formation of the soluble double nitrite of ruthenium and potassium, (K3Ru(N02)6). To a solution of ruthenium trichloride add a solution of potassium nitrite. Note the color. Add ammonium sulphide to the solution.
Experiment 155. Precipitation -of ruthenium hydroxide,. (Ru(OH)3). To a solution of ruthenium trichloride add sodium or potassium hydroxide in solution.
Experiment 156. Precipitation of metallic ruthenium. To an acid solution of a ruthenium salt add metallic zinc.
GOLD, Au, 197.2.
Discovery. Gold is probably one of the earliest known of the metals. In very ancient records frequent mention is made of its uses. As far back as 3600 B.C. in the Egyp- tian code of Menes a ratio of value between gold and silver (2.5:1) is mentioned. Rock carvings of Upper Egypt dating from 2500 B.C. show crude representations of the washing of gold-bearing sands in stone basins, and of the melting of the metal in simple furnaces by means of mouth blowpipes. In fact the discovery of gold dates back to the beginnings of civilization. The search for it furnished the motive of many voyages of discovery and conquest, which resulted in the extension of civilization; and from the desire to change the base metals into gold sprang the study of alchemy, from which developed the science of chemistry.
Occurrence. Gold occurs in nature both free and in combination. Free or native gold is found (i) as vein gold, in the quartz veins which intersect metamorphic rocks, and (2) as placer gold, generally in the form of grains or nuggets, in alluvial deposits of streams. Native gold is.
X42 THE RARER ELEMENTS.
usually alloyed with 'silver, which sometimes amounts to as much as fifteen per cent, of the alloy. Iron and copper are sometimes present, and bismuth, palladium, and rho- dium alloys are known.
In combination gold is found as follows:
Petzite, (AgAu)2Te, contains ...... 18-24% Au
Sylvanite, (AuAg)Te2, " ...... 26-29% "
Goldschmidtite, Au2AgTe6, " ...... 31-32% "
Krennerite, (Au,Ag)Te2-AuTe2, " ...... 30-34% "
Calaverite, (Au,Ag Te2-AuTe2, « ...... 38-42% "
Kalgoorlite, HgAu2Ag6Te6, " ...... 20-21% "
Nagyagite, Au2PbuSb3Te7S17, " ......
Extraction. The six processes indicated below follow the principal methods that have been employed for the extraction of gold.
(1) Washing or Hydraulicking. This method is applied mainly to placer deposits. Powerful jets of water are directed upon the gold-bearing sands, causing them to pass through a series of sluices. Because of its higher specific gravity the gold is largely left behind, while the other materials are carried away.
(2) Amalgamation (primitive}. In this process the crushed ore or the gold-bearing sand is first washed, to remove the greater part of the light, worthless material, and the remainder is rubbed with mercury in a mortar. The amalgam thus obtained is heated, whereupon the mercury is volatilized and the gold remains.
(3) Stamp battery amalgamation. The ore is pulverized and mixed with water, and in the form of pulp caused to pass over a series of* amalgamated copper plates. Gold amalgam forms on the plates, and from time to time it is removed and cupelled.
(4) Chlorination. (a) Vat process. The crushed ore is placed loosely in large vats and moistened with water.
GOLD. 143
Chlorine is forced in, and the whole is allowed to stand for about twenty -four hours. The material is then leached with water until the washings give no further test for gold. The solution of gold chloride thus obtained is treated with sulphur dioxide, to destroy the excess of chlorine, and then with hydrogen sulphide. The gold sulphide thus precipi- tated is decomposed with borax and the gold is melted into bullion.
(b) Barrel process. Into large barrels are put water and sulphuric acid, the ore, and chloride of lime. The barrels are then closed and rotated for a period varying from one hour to four hours. At the end of that time the con- tents are leached and the gold is extracted as described above.
The chlorination process is generally applied to low- grade ores, and these must have been roasted unless the gold occurs in them native.
(5) Cyanide process. The ore, ground fine, is placed in large vats, and a dilute solution (.2-. 5%) of potassium cyanide is forced in. After a time the solution is drawn off and passed over zinc shavings, upon which the gold is de- posited as a black slime. The mixture of zinc and gold is either treated with sulphuric acid, to dissolve the zinc, or roasted with a flux of niter and carbonate of soda. The reactions which take place in the cyanide process may be represented as follows:
(1) 4Au+8KCN + O2 + 2H2O=4KAu(CN)2H-4KOH.
(2) 2KAu(CN)2 + 2Zn + 2H2O =
2KOH + H2 + 2Zn(CN)2
(6) Smelting. In smelting the gold ore is mixed with some other metallic ore appropriately chosen, and the mixture is subjected to intense heat. The gold alloys with the other metal, and the alloy is separated from the residue, or slag, and worked for gold. Three modifications
144 THE RARER ELEMENTS.
of this important process are in common use, viz., lead, copper matte, and iron matte smelting. The process of lead-smelting is in outline as follows: The alloy obtained by heating a mixture of gold and lead ores is melted with zinc. The gold and silver combine with the zinc and rise to the surface, leaving the lead below. The alloy of gold, silver, and zinc is then skimmed off and roasted. The zinc passes off, leaving the gold and silver, which are separated by electrolysis.
The Element. A. Preparation. As extracted from its ores gold is in the elementary condition (vid. Extraction).
B. Properties. Of a characteristic yellow color, gold is the most malleable and ductile of the metals. It is about as soft as silver. It is insoluble in acids, but is attacked by aqua regia, chlorine, bromine, and potassium cyanide. Its melting-point is 1037° C., — just above that of copper. Gold alloys with nearly all the metals. It is occasionally found crystallized in the cubic system. It is a good conductor of heat and electricity. Its specific gravity is 19.49.
Compounds. A. Typical forms. The following com- pounds of gold may be considered typical forms:
Oxides Au2O Au2O2 Au2O3
Hydroxide Au(OH)3
Chlorides AuCl Au2Cl4 AuCl3
Double chlorides, x
many of the types AuCl3 • RC1
AuCl3-RCl3
Bromides AuBr Au2Br4 AuBr3
Double bromides, T
of the type AuBr3 • RBr
Iodides Aul AuI3
Double iodides, of T
the type AuI3-RI
Sulphides Au2S Au2S2 Au2S3
2Au2S3-5Ag2S Double sulphides . . Au2S • Na2S 2 Au2S3 • sMo^
Au2S3-3Mo$4
GOLD. 145
Sulphites (double) Au2SO3 • 3Na2SO3+ 3H2O Au2(SO3)3 • sK2SO3+ 5H2O
Sulphates AuSO4 Au2(SO4)3- K2SO4
Nitrate Au(NO3)3-HNOj,
Cyanides AuCN Au(CN)3
Double cyanides. . AuCN • KCN Au( CN) 3 • KCN, etc.
Sulphocyanides. . . AuCNS • KCNS Au(CNS)3 • KCNS
B. Characteristics. The compounds of gold are known chiefly in two conditions of oxidation, of which attrous oxide, (Au2O), and auric oxide, (Au2O3), serve as types. When metallic gold is dissolved in aqua regia auric chloride is formed, a yellow crystalline salt soluble in water; when auric chloride is heated to 180° C. it goes over to aurous chloride, a white powder insoluble in water. The aurous salts resemble the salts of silver and of copper in the cuprous condition; the auric salts resemble those of aluminum and of iron in the ferric condition. The auric hydroxide, (Au(OH)3), is acidic
in character and unites with bases to form aurates of the
i
type RAuO2. Hydrogen sulphide precipitates brownish- black auric sulphide, (Au2S3 or Au2S2 + S), from cold solu- tions of gold salts, and steel-gray aurous sulphide, (Au2S or Au2S + S), from hot solutions. Salts of gold in solution are easily reduced to the metal by reducing agents.
Estimation. A. Gravimetric. Gold is weighed as the metal. From solutions it is precipitated by reducing agents, such as ferrous sulphate, oxalic acid, formaldehyde, and hydrogen dioxide in alkaline solution.
B. Volumetric. Gold may be determined volumetrically (i) by allowing potassium iodide to act upon auric chloride, (AuCl3 + 3KI=3KCl + AuI + I2), and estimating the iodine thus freed by means of thiosulphate (Peterson, Zeitsch. anorg. Chem. xix, 63; Gooch and Morley, Amer. Jour. Sci. [4] vni, 261; Maxson, Amer. Jour. Sci. [4] xvi); (2) by warming a solution of auric chloride with a measured amount of arsenious acid solution which must be in ex-
146 THE RARER ELEMENTS.
cess, (3As2O3 + 4AuCl3 + 6H2O = 3As2O5 + 1 2HC1 + 4Au), and determining the excess of arsenious acid by iodine in the usual way (Rupp, Ber. Dtsch. chem. Ges. xxxv, 2011; Maxson, loc. cit.).
Separation. Gold and platinum fall into the analyt- ical group of arsenic, antimony, and tin. From these they may be separated by the following process: fusion of the sulphides with sodium carbonate and niter, and removal of the arsenic by extraction with water ; treatment of the insoluble residue with zinc and hydrochloric acid, which reduces the tin and antimony to the metallic con- dition; boiling with hydrochloric acid, which dissolves the tin; then with nitric and tartaric acids, which dissolves the antimony, leaving gold and platinum.
For the separation of gold from platinum and the plat- inum metals vid. Platinum.
EXPERIMENTAL WORK ON GOLD.
Experiment 157. Extraction of gold from its ores, (a) Digest for several hours in a beaker on a steam-bath about 100 grm. of finely ground gold ore with a dilute solution of potassium cyanide, adding water from time to time to re- place the liquid evaporated. Filter, pass the filtrate several times through a funnel containing zinc shavings, until upon testing the liquid with a fresh piece of zinc no discoloration of the metal is observed. Dissolve the zinc in hydrochloric acid to remove the black deposit. Filter, dissolve the resi- due in aqua regia, remove the excess of acid by evaporation, and test for gold by stannous chloride, ferrous sulphate, etc.
(b) Mix in a glass-stoppered bottle about 100 grm. of finely ground ' ' oxidized ' ' or previously roasted ore with a little bleaching salt and enough water to give the mass the consistency of thin paste. Then add gradually enough sulphuric acid to start an evolution of chlorine. Close the
EXPERIMENTAL WORK ON GOLD. 147
bottle and shake it, to insure a thorough mixing of the contents. Allow the action to go on for several hours, agitat- ing the mass occasionally, and taking care to have an excess of chlorine present throughout the process. Extract with water, concentrate if necessary, and test for gold in the solution. A two per cent, solution of bromine may be substituted for the materials generating chlorine.
Experiment 158. Precipitation of the sulphide of gold, (Au2S3 or Au2S2 + S ?) . Into a cold solution of auric chloride pass hydrogen sulphide. Try the action of yellow am- monium sulphide upon the precipitate.
Experiment 159. Formation of aurous iodide, (AuT). To a solution of auric chloride add a few drops of a dilute solution of potassium iodide. Note the precipitate, and the solvent action of an excess of the reagent.
Experiment 160. Formation of ammonia aurate, "ful- minating gold" ((NH3)2Au2O3). To a very dilute solution of a salt of gold add a little ammonium hydroxide.
CAUTION. Do not attempt to isolate the precipitate. Note that neither potassium nor sodium hydroxide gives a precipitate under similar conditions of dilution.
Experiment 161. Formation of the "purple of Cassius" To a very dilute solution of a gold salt add a drop or two of dilute stannous chloride solution.
Experiment 162. Precipitation of gold. To separate portions of a solution of a gold salt add ferrous sulphate and oxalic acid in solution. Observe the color by trans- mitted light.
Experiment 163. Solvent action of certain reagents upon gold. Try separately upon metallic gold the action of aqua regia, chlorine or bromine water, and a dilute solution of potassium cyanide.
148 THE RARER ELEMENTS.
THE NEWLY DISCOVERED GASES OF THE ATMOSPHERE.
Argon, A, 39.9 Krypton, Kr, 81.8
Helium, He, 4 Neon, Ne, 20
Xenon, X, 128
Discovery. In 1892 Lord Rayleigh, while engaged in the study of the density of elementary gases, made the im- portant observation that the nitrogen obtained from nitric acid or ammonia was about one half of one per cent, lighter than atmospheric nitrogen (Proc. Royal Soc. LV, 340). An investigation of this difference led to the discovery two years later of the gas Argon (dpyos, inert) by Lord Rayleigh and Professor William Ramsay (Proc. Royal Soc. LVII, 265; Amer. Chem. Jour, xvn, 225). An experi- ment made by Cavendish in 1785 seems also to have resulted in the separation of this gas (Phil. Trans. Roy. Soc. (1785) LXXV, 372, and (1788) LXXVIII, 271).
In the course of analytical work on uraninite undertaken by Hillebrand in 1888, a gas which he thought to be nitro- gen was obtained upon the boiling of the mineral with dilute sulphuric acid (Bull. U. S. Geol. Sur. No. 78, p. 43 ; Amer. Jour. Sci. [3] XL, 384). In 1895 Ramsay, whose attention had been called to Hillebrand 's work, and who doubted whether nitrogen could be obtained by the method de- scribed, prepared some of the gas by Hillebrand 's process from cleveite, a variety of uraninite. He then sparked the gas with oxygen over soda to remove the nitrogen. Ob- serving very little contraction, he removed the excess of oxygen by absorption with potassium pyrogallate and examined the residual gas spectroscopically. The spec- trum showed argon and hydrogen lines, and in addition a brilliant yellow line, (D3), coincident with the helium line
THE NEWLY DISCOVERED GASES OF THE ATMOSPHERE. 149
of the solar chromosphere discovered by Lockyer in 1868 (Proc. Royal Soc. LVIII, 65, 81). The only previous note regarding helium as a terrestrial element is a statement by Palmieri, in 1881, that a substance ejected from Vesu- vius showed the line D3 (Rend. Ace. di Napoli xx, 233) ; he failed to describe his treatment of the material, how- ever, and he seems to have made no further investigation of the subject. Kayser first detected helium in the atmos- phere, in 1895 (Chem. News LXXII, 89), several months after Ramsay's discovery.
The year 1898 witnessed the discovery by Ramsay and Travers of three other inert atmospheric gases. Having .allowed all but one seventy -fifth of a given amount of liquid air to evaporate, and having removed the oxygen and nitrogen remaining by sparking over soda, they ob- tained a small amount of a gas which, while showing a feeble spectrum of argon, gave new lines as well. This newly discovered gas they named Krypton, from Kpvnros, hid- den (Proc. Royal Soc. LXIII, 405).
By fractioning the residue after the evaporation of a large amount of liquid air they found evidence of a gas of greater density than krypton, and for this heavy gaseous •element the name Xenon (Zeros, stranger) was chosen (Chem. News LXXVIII, 154).
The third discovery of the year by the same investigators was that of Neon (reo?, new), a gas of less density than .argon. The first fraction obtained from the evaporation of liquid air was mixed with oxygen and sparked over soda, and the excess of oxygen was removed by phosphorus. The remaining gas yielded a new and characteristic spectrum (Proc. Royal Soc. LXIII, 437).
Occurrence. Argon forms about one per cent, of the air by volume. It is found in small quantities in gases from certain mineral springs, e.g. Bath, Cauterets, Wildbad, Voslau, the sulphur spring of Harrogate; also in the gases
15° THE RARER ELEMENTS.
occluded in rock salt. It has been detected in some helium- bearing minerals, e.g. cleveite, broggerite, uraninite, and malacon.
Helium, the existence of which was first observed in the sun, occurs in very small proportion in the terrestrial atmosphere. The chief sources of the gas have been certain rare minerals, among which are uraninite (pitch -blende) , cleveite, monazite, fergusonite, samarskite, columbite, and malacon. It has been found also in some mineral springs r e.g. Bath, Cauterets, and Adano, near Padua.
The other gases of this group are present in the air in very minute quantities. Neon is said to constitute 0.002 5 % and krypton 0.00002% of the atmosphere. Traces of neon have been detected in the helium from the springs of Bath.
Extraction. Argon, contaminated with a greater or less percentage of the associated gases, may be extracted by the following methods :
(1) From atmospheric nitrogen. The nitrogen is passed over red-hot magnesium filings; a nitride is thus formed, while the argon is left uncombined (Ramsay). Heated lithium may be substituted for magnesium.
(2) From air. Induction sparks are passed through a mixture of oxygen and air contained in a vessel which is inverted over caustic potash. The oxygen and nitrogen combine and dissolve in the potassium hydroxide, leaving the argon (Rayleigh).
Helium may be obtained from its mineral sources by boiling the material with dilute sulphuric acid, or by heat- ing in vacuo.
Krypton and xenon are extracted as follows: After the evaporation of a large amount of liquid air the residue is freed from oxygen and nitrogen and liquefied by the immersion of the containing Vessel in liquid air. The greater part of the argon can be removed as soon as the temperature rises. By repetitions of this process the
THE NEWLY DISCOVERED GASES OF THE ATMOSPHERE. I5L
three gases can be separated from one another, krypton exercising much greater vapor pressure than xenon at the temperature of boiling air (Ramsay and Travers, Proc. Royal Soc. LXVII, 330).
Neon is obtained from the gas, largely nitrogen, that first evaporates from liquid air. This gas is liquefied, and a current of air is blown through it. The material that first evaporates is passed over red-hot copper, to remove the oxygen, and after being freed from nitrogen in the usual manner, is liquefied. By fractional distillation helium and neon are removed, and argon is left behind. By the use of liquefied hydrogen helium and neon are separated, as neon is liquefied or solidified at the temperature of boil- ing hydrogen, while helium remains gaseous. Several fractionations are necessary to obtain pure neon (Ramsay and Travers, Proc. Royal Soc. LXVII, 330).
Properties. The newly discovered constituents of the atmosphere are inert, colorless, probably monatomic gases, which have not been known to form definite compounds.
Argon is somewhat soluble * in water. Its density is 19.96 and its specific heat 1.645. It solidifies at — 191° C., melts at — 189.5 °C., and boils at — 185° C. Argon gives two distinct spectra, according to the strength of the in- duction current employed and the degree of exhaustion in the tube. When the pressure of the argon is 3 mm. the discharge is orange-red and the spectrum shows two par- ticularly prominent red lines. If the pressure is further reduced, and a Ley den jar is intercalated in the circuit, the discharge becomes steel-blue and the spectrum shows a different set of lines (Crookes, Amer. Chem. Jour, xvn,
251)-
Helium is slightly soluble t in water. Its density is i .98. Its spectrum is characterized by five brilliant lines, —
* 100 volumes of water will dissolve 3.7 volumes of argon at 20° C.
f 100 volumes of water will dissolve about 1.4 volumes of helium at 20° C.
152 THE RARER ELEMENTS.
one each in the red, yellow, blue-green, blue, and violet. Reference has already been made to the yellow line D3.
Krypton is less volatile than argon. Its density is 40.78. Its spectrum is characterized by a bright line in the yellow and one in the green.
Xenon also is less volatile than argon, and it has a much higher boiling-point. Its density is 64. Its spectrum is similar in character to that of argon, though the position of the lines is different. With the ordinary discharge the glow in the tube is blue and the spectrum shows three red and about five brilliant blue lines. With the jar and spark-gap the glow changes to green and the spectrum is characterized by four green lines (Ramsay and Travers, Chem. News LXXVIII, 155).
Neon is more volatile than argon. Its density is 9.96. Its spectrum is characterized by bright lines in the red, orange, and yellow, and faint lines in the blue and violet.
RECENT UNCONFIRMED DISCOVERIES.
In September, 1896, Barriere announced the discovery in monazite sands of an unknown element which differed from the members of the cerium group and from thorium and zirconium in forming no double sulphate with either sodium or potassium sulphate, and from the members of the yttrium group in being precipitable by sodium thio- sulphate. He gave as the approximate atomic weight of the element 104, and proposed for it the name Lucium (Chem. News LXXIV, 159). A few weeks later Crookes examined some of Barriere 's material, and declared lucium to be yttrium with some admixture of erbium, didymium, and ytterbium (Chem. News LXXIV, 259). The following year Shapleigh confirmed Crookes 's results, and pointed out the weak places in Barriere 's deductions (Chem. News LXXVI, 41).
RECENT UNCONFIRMED DISCOVERIES. 153
In 1897 Chruschtschoff called attention to a new member of the didymium group which he distinguished from praseo- and neodymium by the blue color of its salts. The spec- trum was in part that of neodymium. He suggested the name Glaukodymium (yhavxos, blue-gray) (Jour. Rus. Phys. Chem. Soc. xxix, 206). Although it is considered quite possible that praseo- and neodymium are not simple bodies, no confirmation of ChruschtschofI 's discovery has appeared.
Nasini, Anderlini, and Salvadori, in 1898, discovered in the spectra of gases from the Solfatara di Pozzuoli and the fumaroles of Vesuvius a line (1474 K) of the corona never before observed in terrestrial matter. They called the unknown gas the presence of which was thus indicated Coronium (Atti R. Accad. dei Lincei, Roma [5] vn, II, 73 ; Amer. Chem. Jour, xx, 698).
The same year Brush, while studying the relation of pressure to the heat conductivity of gases, extracted from glass a gaseous substance which seemed to be different from all known gases. He concluded that its heat con- ductivity was 100 if H = i ; its density, also referred to hy- drogen as the standard, was o.oooi, and its molecular weight 0.0002. He suggested that it might be the ether of the physicist, and proposed for it the name Etherion (Amer. Chem. Jour, xx, 873; Chem. News LXXVIII, 197). Crookes, upon examination of the evidence given by Brush, pronounced the gas probably water vapor (Chem. News LXXVIII, 221).
About the time that Ramsay and Travers announced the discovery of krypton and neon in 1898, they first mentioned Metargon (Proc. Royal Soc. LXIII, 437). It was obtained in the liquefaction of large quantities of argon, remaining in the form of a white solid after the liquid had largely boiled away. The gas obtained from this solid had a density close to that of argon; its spectrum
154 THE RARER ELEMENTS.
resembled that of argon and also that of carbon. Two years later the same investigators announced that this gas was merely argon mixed with some compounds of car- bon (Proc. Royal Soc. LXVII, 329).
Crookes, in 1899, stated that as the result of a long series of fractional fusions, crystallizations, and precipi- tations of salts obtained from yttrium earth, he had dis- covered an element which he had named Monium. A little later, in recognition of the Queen 's jubilee, he changed the name to Victorium (Proc. Royal Soc. LXV, 237). The new element was described by him as having a pale-brown color, as being less basic than yttrium, as being easily soluble in acids, and as forming with potassium sulphate a double sulphate less soluble than the corresponding salt of yttrium, and more soluble than the corresponding salts of the cerium group. Assuming the oxide to be Vc2O3, he calculated the atomic weight as 117.
Previous to 1898 the presence of "radiant matter" in uranium and thorium minerals, particularly in pitch- blende, had frequently been noticed, and investigations of the phenomenon had been carried on. It is not yet fully determined whether the actinism is due to the pres- ence in these minerals of certain elements having distinct radioactive properties, though three substances possessing this quality, and differing in other characteristics, have been isolated and described as compounds of newly dis- covered elements. In 1898 P. and C. Curie announced the discovery in pitch-blende of Polonium (Polonia, Poland), and the next year, together with Bemont, of another element, Radium* (Compt. rend, cxxvn, 175, 1215). Also in 1899 Debierne named Actinium as a third radioactive element (Compt. rend, cxxx, 906).
* Recent work on this interesting substance has led many chemists to assign radium a place among the elements. See Mme. Curie, Compt. rend, cxxxv, 161; Runge and Precht, Annal. der Phys. u. Chem. [4] x, 655;
Hammer, Chem. News LXXXVII, 25.
RECENT UNCONFIRMED DISCOVERIES. 155
In the summer of 1901 Baskerville described some work on pure thorium salts which had suggested to him the probable existence of an unknown element associated with thorium. He found it possible, by fractioning pure thorium dioxide, to obtain two oxides of specific gravity 9 25 and 10.53 respectively. Radioactivity increased with specific gravity, the oxide of lower specific gravity being practically inactive. A determination of the atomic weight of thorium from the pure tetrachloride gave 223.25, as against 232.5, the generally accepted value. The probable atomic weight of the new element was given as between 260 and 280, and the name proposed for it was Carolinium, because the thorium salts were prepared from the monazite sands of the Carolinas (Jour. Amer. Chem. Soc. xxm, 761).
INDEX.
PAGE
Actinium 154
Argon 148
Beryllium 16
Caesium. I
Carolinium 155
Cerium 3°
Columbium 65
Coronium 153
Decipium. 27
Didymium 36
Dysprosium.. 27
Erbium 27
Erythronium 84
Etherion 153
Gadolinium 27
Gallium 75
Germanium 55
Glaukodymium 153
Glucinum 16
Gold 141
Helium 149
Holmium 27
Indium 72
Indium 130
Krypton 149
Lanthanum 36
Lithium n
Lucium 152
Menachite 58
Metargon 153
Molybdenum 91
Monium 154
Neodymium 36
Neon 149
Niobium 65
Ochroite 30
Osmium 130
Palladium 130
Philippium 27
Platinum .• 122
Pluranium 131
Polinium 131
Polonium 154
Praseodymium 36
Radium 154
Rhodium 130
Rubidium 5
Ruthenium 130
Samarium 27
Scandium 27
Selenium 1 14
Tantalum 65
Tellurium 107
Terbium 27
Thallium 78
Thorium 44
Thulium 27
Titanium .' 58
Tungsten 96
Uranium 101
Vanadium 84
Victorium 154
Xenon 149
Ytterbium 27
Yttrium 20
Zirconium 50
157
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Law of Contracts 8vo, 3 oo
Woodbury's Fire Protection of Mills 8vo , 2 50
Worcester and Atkinson's Small Hospitals, Establishment and Maintenance, Suggestions^for Hospital Architecture, with Plans for a Small Hospital.
12010, i 25
The World's Columbian Exposition of 1893 Large 4to, i oo
ARMY AND, NAVY.
Bernadou's Smokeless Powder, Nitro-cellulose, and the Theory of the Cellulose
Molecule i2mo, 2 50
* Bruff's Text-book Ordnance and Gunnery 8vo, 6 oo
Chase's Screw Propellers and Marine Propulsion 8vo, 3 oo
Craig's Azimuth 4to, 3 So
Crehore and Squire's Polarizing Photo-chronograph 8vo, 3 oo
Cronkhite's Gunnery for Non-commissioned Officers 24010. morocco, 2 oo
* Davis's Elements of Law 8vo, 2 50
* Treatise on the Military Law of United States 8vo, 7 oo
* Sheep 7 50
De Brack's Cavalry Outpost Duties. (Carr.) 24010, morocco, 2 oo
Dietz's Soldier's First Aid Handbook i6mo, morocco, i 25
* Dredge's Modero French Artillery 4to, half morocco, 15 oo
Durand's Resistance and Propulsion of Ships 8vo, 5 oo
* Dyer's Handbook of Light Artillery 12010, 3 oo
Eissler's Modern High Explosives .*. ..* :?".' 8vo, 4 oo
* Fiebeger's Text-book on Field Fortification Small 8vo, 2 oo
Hamilton's The Gunner's Catechism i8mo, i oo
* Hoff's Elementary Naval Tactics 8vo, i 50
Ingalls's Handbook of Problems in Direct Fire 8vo, 4 oo
* Ballistic Tables 8vo, i 50
* Lyons's Treatise on Electromagoetic Phenomena. Vols. I. and II . . 8vo, each, 6 oo
* Mahan's Permaoeot Fortifications. (Mercur.) 8vo, half morocco, 7 50
Manual for Courts-martial 16010 morocco, i 50
* Mercur's Attack of Fortified Places 12010, 2 oo
* ' Elements of the Art of War 8vo, 4 oo
Metcalf's^Cost of Manufactures — And the Admioistratioo of Workshops, Public
and Private 8vo, 5 oo
* Ordnance and Gunnery . : 12010, 5 oo
Murray's lofaotry Drill Regulatioos 18010, paper, 10
* Phelps's Practical Marioe Surveyiog 8vo, 2 50
Powell's Army Officer's Examiner 12010, 4 oo
Sharpe's Art of Subsisting Armies in War 18010, morocco, i 50
2
* Walke's Lectures on Explosives 8vo, 4 OO
* Wheeler's Siege Operations and Military Mining 8vo, 2 oo
Winthrop's Abridgment of Military Law I2mo, 2 50
Woodhull's Notes on Military Hygiene i6mo, i 50
Young's Simple Elements of Navigation i6mo, morocco, i oo
Second Edition, Enlarged and Revised i6mo, morocco 2 oo
ASSAYING.
Fletcher's Practical Instructions in Quantitative Assaying with the Blowpipe.
1 2 mo, morocco, i 50
Furman's Manual of Practical Assaying 8vo, 3 oo
Miller's Manual of Assaying 12010, i oo
O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 oo
Ricketts and Miller's Notes on Assaying 8vo, 3 oo
Hike's Modern Electrolytic Copper Refining 8vo, 3 oo
Wilson's Cyanide Processes I2mo, i 50
Chlorination Process I2mo . I 50
ASTRONOMY.
Comstock's Field Astronomy for Engineers 8vo, 2 50
raig's Azimuth 4to, 3 50
Doolittle's Treatise on Practical Astronomy 8vo, 4 oo
Gore's Elements of Geodesy 8vo, 2 50
Hayford's Text-book of Geodetic Astronomy .8vo, 3 oo
Merriman's Elements of Precise Surveying and Geodesy 8vo, 2 50
* Michie and Harlow's Practical Astronomy 8vo, 3 oo
* White's Elements of Theoretical and Descriptive Astronomy 12 mo, 2 oo
BOTANY.
Davenport's Statistical Methods, with Special Reference to Biological Variation.
i6mo, morocco, i 25
Thome and Bennett's Structural and Physiological Botany i6mo, 2 25
Westermaier's Compendium of General Botany. (Schneider.) 8vo, 2 oo
CHEMISTRY.
Adriance's Laboratory Calculations and Specific Gravity Tables 12010, / 25
Allen's Tables for Iron Analysis 8vo, 3 oo
Arnold's Compendium of Chemistry. (Mandel.) (In preparation.)
Austen's Notes for Chemical Students I2mo, i 50
Bernadou's Smokeless Powder. — Nitro-cellulose, and Theory of the Cellulose
Molecule i2mo, 2 50
Bolton's Quantitative Analysis 8vo, i 50
* Browning's Introduction to the Rarer Elements 8vo, I 50
Brush and Penfield's Manual of Determinative Mineralogy 8vo, 4 oo
Classen's Quantitative Chemical Analysis by Electrolysis. (Boltwood.) . . . .8vo 3 oo
Cohn's Indicators and Test-papers i2mo, 2 oo
Tests and Reagents 8vo, 3 oo
Copeland's Manual of Bacteriology. (In preparation.)
Craft's Short Course in Qualitative Chemical Analysis. (Schaeffer.). . . . I2mo, 2 oo
Drechsel's Chemical Reactions. (Merrill.) 1 2mo, i 25
Duhem's Thermodynamics and Chemistry. (Burgess.) (Shortly.)
Eissler's Modern High Explosives 8vo, 4 oo
3
Effront's Enzymes and their Applications. (Prescott.) 8vo, 3 oo
Erdmann's Introduction to Chemical Preparations. (Dunlap.) i2mo, i 25
Fletcher's Practical Instructions in Quantitative Assaying with the Blowpipe.
121110, morocco, i 50
Fowler's Sewage Works Analyses i2mo, 2 oo
Fresenius's Manual of Qualitative Chemical Analysis. (Wells.) 8vo, 5 oo
Manual of Qualitative Chemical Analysis. Parti. Descriptive. (Wells.)
8vo, 3 oo
System of Instruction in Quantitative Chemical Analysis. (Cohn.) 2 vols. (Shortly.)
Fuertes's Water and Public Health i2mo, i 50
Furman's Manual of Practical Assaying 8vo, 3 oo
Gill's Gas and Fuel Analysis for Engineers i2mo, i 25
Grotenfelt's Principles of Modern Dairy Practice. ( Woll.) i2mo, 2 oo
Hammarsten's Text-book of Physiological Chemistry. (Mandel.) 8vo, 4 oo
Helm's Principles of Mathematical Chemistry. (Morgan.) 121110. i 50
Hinds's Inorganic Chemistry 8vo, 3 oo
* Laboratory Manual for Students i2mo, 75
Ho lie man's Text-book of Inorganic Chemistry. (Cooper.) 8vo, 2 50
Text-book of Organic Chemistry. (Walker and Mott.) 8vo, 2 50
Hopkins's Oil-chemists' Handbook 8vo, 3 oo
Jackson's Directions for Laboratory Work in Physiological Chemistry. .8vo, i oo
Keep's Cast Iron 8vo, 2 50
Ladd's Manual of Quantitative Chemical Analysis i2mo. i oo
Landauer's Spectrum Analysis. (Tingle.) 8vo, 3 oo
Lassar-Cohn's Practical Urinary Analysis. (Lorenz.) 12 mo, i oo
Leach's The Inspection and Analysis of Food with Special Reference to State
Control. (In preparation.)
Lob's Electrolysis and Electrosynthesis of Organic Compounds. (Lorenz.) i2mo, i oo
Mandel's Handbook for Bio-chemical Laboratory 12 mo, i 50
Mason's Water-supply. (Considered Principally from a Sanitary Standpoint.)
3d Edition, Rewritten 8vo, 4 oo
Examination of Water. (Chemical and Bacteriological.) i2mo, i 25
Meyer's Determination of Radicles in Carbon Compounds. (Tingle.). . i2mo, i oo
Miller's Manual of Assaying i2mo, i oo
Mixter's Elementary Text-book of Chemistry i2mo, i 50
Morgan's Outline of Theory of Solution and its Results i2mo, i oo
Elements of Physical Chemistry 121110. 2 oo
Nichols's Water-supply. (Considered mainly from a Chemical and Sanitary
Standpoint, 1883.) 8vo, 2 50
O'Brine's Laboratory Guide in Chemical Analysis 8vo, 2 oo
O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 oo
Ost and Kolbeck's Text-book of Chemical Technology. (Lorenz — Bozart.)
(In preparation.)
* Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests.
8vo, paper, 50
Pictet's The Alkaloids and their Chemical Constitution. (Biddle.) (In preparation.)
Pinner's Introduction to Organic Chemistry. (Austen.) i2mo, i 50
Poole's Calorific Power of Fuels 8voy 3 oo
* Reisig's Guide to Piece-dyeing 8vo, 25 oo
Richards and Woodman's Air .Water, and Food from a Sanitary Standpoint . 8vo, 2 oo
Richards's Cost of Living as Modified by Sanitary Science i2mo, i oo
Cost of Food a Study in Dietaries i2mo, i oo
* Richards and Williams's The Dietary Computer 8vo, i 50
Ricketts and Russell's Skeleton Notes upon Inorganic Chemistry. (Part I. —
Non-metallic Elements.) 8vo, morocco, 75
Ricketts and Miller's Notes on Assaying 8vo, 3 oo
d eal's Sewage and the Bacterial Purification of Sewage 8vo, 3 50
Ruddiman's Incompatibilities in Prescriptions 8vo, 2 oo
Schimpf s Text-book of Volumetric Analysis i2mo. 2 50
Spencer's Handbook for Chemists of Beet-sugar Houses i6mo, morocco, 3 oo
Handbook for Sugar Manufacturers and their Chemists. . i6mo, morocco, 2 oo
Stockbridge's Rocks and Soils 8vo, 2 50
* Tillman's Elementary Lessons in Heat 8vo, i 50
* Descriptive General Chemistry 8vo 3 oo
TreadwelTs Qualitative Analysis. (HalL) 8vo, 3 oo
Turneaure and Russell's Public Water-supplies 8vo, 5 oo
Van Deventer's Physical Chemistry for Beginners. (Boltwood.) i2tno, i 50
* Walke's Lectures on Explosive's 8vo, 4 oo
Wells's Laboratory Guide in Qualitative Chemical Analysis 8vo, i 50
Short Course in Inorganic Qualitative Chemical Analysis for Engineering
Students i2mo, i 50
Whipple's Microscopy of Drinking-water 8vo, 3 50
Wiechmann's Sugar Analysis Small 8vo, 2 50
Wilson's Cyanide Processes i2mo, i 50
Chlorination Process .• ... . . i2mo . i 50
Wulling's Elementary Course in Inorganic Pharmaceutical and Medical Chem- istry I2mo, 2 oo
CIVIL ENGINEERING.
BRIDGES AND ROOFS. HYDRAULICS. MATERIALS OF ENGINEERING. RAILWAY ENGINEERING.
Baker's Engineers' Surveying Instruments i2mo, 3 oo
Bixby's Graphical Computing Table Paper, ig^X 24$ inches 25
** Burr's Ancient and Modern Engineering and the Isthmian Canal. (Postage
27 cents additional.) 8vo, n*. 3 50
Comstock's Field Astronomy for Engineers 8vo, ^ 50
Davis's Elevation and Stadia Tables 8vo, I oo
Elliott's Engineering for Land Drainage i2mo, I 50
Practical Farm Drainage 121110, i oo
FolwelTs Sewerage. (Designing and Maintenance.) 8vo, 3 oo
Freitag's Architectural Engineering. 2d Edition, Rewritten 8vo, 3 50
French and Ives's Stereotomy 8vo, 2 50
Goodhue's Municipal Improvements 1 2mo, ' x 75
Goodrich's Economic Disposal of Towns' Refuse 8vo, 3 50
Gore's Elements of Geodesy 8vo, 2 50
Hayford's Text-book of Geodetic Astronomy 8vo, 3 oo
Howe's Retaining Walls for Earth i2mo, i 25
Johnson's Theory and Practice of Surveying Small 8vo. 4 oo
Statics by Algebraic and Graphic Methods 8vo, 2 oo
Kiersted's Sewage Disposal 121110, i 25
Laplace's Philosophical Essay on Probabilities. (Truscott and Emory.) izmo, 2 oo
Mahan's Treatise on Civil Engineering. (1873,) (Wood.) 8vo0 5 oo
* Descriptive Geometry 8vo, i 50
Merriman's Elements of Precise Surveying and Geodesy 8vo, 2 50
Elements of Sanitary Engineering 8vo, 2 oo
Merriman and Brooks's Handbook for Surveyors . 1 6mo, morocco, 2 oo
Nugent's Plane Surveying 8vo, 3 50
Ogden's Sewer Design i2tno, 2 oo
Patton's Treatise on Civil Engineering 8vo, half leather, 7 50
Reed's Topographical Drawing and Sketching 4to, 5 oo
Rideal'sJSewage and the Bacterial Purification of Sewage 8vo, 3 50
Siebert and Biggin's Modern Stone-cutting and Masonry 8vo, i 50
Smith's Manual of Topographical Drawing. (McMillan.) 8vo, 2 50
5
Sondericker's Graphic Statics, wun Applications to Trusses, Beams, ana Arches. (Shortly.)
* Trantwine's Civil Engineer's Pocket-book i6mo, morocco, 5 oo
Wait's Engineering and Architectural Jurisprudence 8vo, 6 oo
Sheep, 6 50
Law of Operations Preliminary to Construction in Engineering and Archi- tecture, 8vo, 5^00
Sheep, 5 50
Law of Contracts 8vo, 3 oo
Warren's Stereotomy — Problems in Stone-cutting 8vo, 2 50
Webb's Problems in the U«e and Adjustment of Engineering Instruments.
i6mo, morocco, i 25
* Wheeler's Elementary Course of Civil Engineering 8vo, 4 oo
Wilson's Topographic Surveying 8vo, 3~5O
BRIDGES AND ROOFS.
Boiler's Practical Treatise on the Construction of Iron Highway Bridges. .8vo, 2 oo
* Thames River Bridge 4to, paper, 5 oo
Burr's Course on the Stresses in Bridges and Roof Trusses, Arched Ribs, and
Suspension Bridges 8vo, 3 50
Du Bois's Mechanics of Engineering. Vol. II Small 4to, 10 oo
Foster's Treatise on Wooden Trestle Bridges 4to, 5 oo
Fowler's Coffer-dam Process for Piers 8vo, 2 50
Greene's Roof Trusses 8vo, i 25
Bridge Trusses 8vo, 2 50
Arches in Wood, Iron, and Stone 8vo, 2 50
Howe's Treatise on Arches 8vo 4 oo
Design of Simple Roof -trusses in Wood and Steel 8vo, 2 oo
Johnson, Bryan, and Turneaure's Theory and Practice in the Designing of
Modern Framed Structures Small 4to, 10 oo
Merriman and Jacoby's Text-book on Roofs and Bridges:
Part I.— Stresses in Simple Trusses 8vo, 2 50
Part II. — Graphic Statics 8vo, 2 50
Part HI.— Bridge Design. 4th Edition, Rewritten 8vo, 2 50
Part IV.— Higher Structures 8vo, 2 50
Morison's Memphis Bridge 4to, 10 oo
Waddell's De Pontibus, a Pocket-book for Bridge Engineers. . . i6mo, morocco, 3 oo
Specifications for Steel Bridges i2mo, i 25
Wood's Treatise on the Theory of the Construction of Bridges and Roofs.Svo, 2 oo Wright's Designing of Draw-spans:
Part I. —Plate-girder Draws 8vo, 2 50
Part II. — Riveted-truss and Pin-connected Long-span Draws 8vo, 2 50
Two parts in one volume 8vo, 3 50
HYDRAULICS.
Bazin's Experiments upon the Contraction of the Liquid Vein Issuing from an
Orifice. (Trautwine.) 8vo, 2 oo
Bovey's Treatise on Hydraulics 8vo, 5 oo
Church's Mechanics of Engineering 8vo, 6 oo
Diagrams of Mean Velocity of Water in Open Channels paper, i 50
Coffin's Graphical Solution of Hydraulic Problems i6mo, morocco, 2 50
Flather's Dynamometers, and the Measurement of Power i2mo, 3 oo
Folwell's Water-supply Engineering 8vo, 4 oo
Frizell's Water-power 8vo, 5 oo
6
Fuertes's Water and Public Health iimo, I 50
Water-filtration Works 12010, 2 50
Ganguillet and Kutter's General Formula for the Uniform Flow of Water in
Rivers and Other Channels. (Hering and Trautwine.) 8vo, 4 oo
Hazen's Filtration of Public Water-supply 8vo, 3 oo
Hazlehurst's Towers and Tanks for Water-works 8vo, 2 50
Herschel's 115 Experiments on the Carrying Capacity of Large, Riveted, Metal
Conduits 8vo, 2 oo
Mason's Water-supply. (Considered Principally from a Sanitary Stand- point.) 3d Edition, Rewritten 8vo, 4 oo
Merriman's Treatise on Hydraulics, pth Edition, Rewritten 8vo, 5 oo
* Michie's Elements of Analytical Mechanics 8vo, 4 oo
Schuyler's Reservoirs for Irrigation, Water-power, and Domestic Water- supply Large 8vo, 5 oo
** Thomas and Watt's Improvement of Riyers. (Post., 44 c. additional), 4to, 6 oo
Turneaure and Russell's Public Water-supplies 8vo. 5 oo
Wegmann's Desien and Construction of Dams 4to, 5 oo
Water-suoolv of the City of New York from 1658 to 1895 4to, 10 oo
Weisbach's Hydraulics and Hydraulic Motors. (Du Bois.) 8vo, 5 oo
Wilson's Manual of Irrigation Engineering Small 8vo. 4 oo
Wolff's Windmill as a Prime Mover 8vo,' 3 oo
Wood's Turbines 8vo, 2 50
Elements of Analytical Mechanics 8vo, 3 oo
MATERIALS OF ENGINEERING.
Baker's Treatise on Masonry Construction 8vo, 5 oo
Roads and Pavements 8vo, 5 oo
Black's United States Public Works Oblong 4to, 5 oo
Bovey's Strength of Materials and Theory of Structures 8vo, 7 So
Burr's Elasticity and Resistance of the Materials of Engineering. 6th Edi- tion, Rewritten 8vo, 7 So
Byrne's Highway Construction 8vo, 5 oo
Inspection of the Materials and Workmanship Employed in Construction.
itfmo, 3 oo
Church's Mechanics of Engineering 8vo, 6 oo
Du Bois's Mechanics of Engineering. VoL I Small 4to, 7 50
Johnson's Materials of Construction Large 8vo, 6 oo
Keep's Cast Iron 8vo, 2 50
Lanza's Applied Mechanics 8vo, 7 50
Martens's Handbook on Testing Materials. (Henning.) 2 vols 8vo, 7 50
Merrill's Stones for Building and Decoration 8vo, 5 oo
Merriman's Text-book on the Mechanics of Materials 8vo, 4 oo
Strength of Materials i2mo, i oo
Metcalf's Steel. A Manual for Steel-users i2tno, 2 oo
Patton's Practical Treatise on Foundations 8vo, 5 oo
Rockwell's Roads and Pavements in France 1 2tno, i 25
Smith's Wire : Its Use and Manufacture Small 4to, 3 oo
Materials of Machines izmo, i oo
Snow's Principal Species of Wood 8vo, 3 50
Spalding's Hydraulic Cement i2mo, 2 oo
Text-book on Roads and Pavements i2mo, 2 oo
Thurston's Materials of Engineering. 3 Parts 8vo, 8 oo
Part I. — Non-metallic Materials of Engineering and Metallurgy 8vo, 2 oo
Part II. — Iron and Steel 8vo, 3 50
Part III. — A Treatise on Brasses, Bronzes, and Other Alloys and their
Constituents 8vo, 2""so
7
Thurston's Text-book of the Materials of Construction 8vo, 5 oo
Tillson's Street Pavements and Paving Materials 8vo, 4 oo
WaddelTs De Pontibus. (A Pocket-book for Bridge Engineers.) . . i6mo, mor., 3 oo
Specifications for Steel Bridges i2mo, i 25
Wood's Treatise on the Resistance of Materials, and an Appendix on the Pres- ervation of Timber 8vo, 2 oo
Elements of Analytical Mechanics 8vo, 3 oo
RAILWAY ENGINEERING.
Andrews's Handbook for Street Railway Engineers. 3X5 inches, morocco, i 25
Berg's Buildings and Structures of American Railroads 4to, 5 oo
Brooks's Handbook of Street Railroad Location i6mo. morocco, i 50
Butts's Civil Engineer's Field-book i6mo, morocco, 2 50
Crandall's Transition Curve i6mo, morocco, i 50
Railway and Other Earthwork Tables 8vo, i 50
Dawson's "Engineering" and Electric Traction Pocket-book. i6mo, morocco, 4 oo
Dredge's History of the Pennsylvania Railroad: (1879) Paper, 5 oo
* Drinker's Tunneling, Explosive Compounds, and Rock Drills, 4to, half mor., 25 oo
Fisher's Table of Cubic Yards Cardboard, 25
Godwin's Railroad Engineers' Field-book and Explorers' Guide i6mo, mor., 2 50
Howard's Transition Curve Field-book i6mo morocco i 50
Hudson's Tables for Calculating the Cubic Contents of Excavations and Em- bankments 8vo, i oo
Molitor and Beard's Manual for Resident Engineers i6mo, i oo
Nagle's Field Manual for Railroad Engineers i6mo, morocco. * oo
Philbrick's Field Manual for Engineers i6mo, morocco, 3 oo
Pratt and Alden's Street-railway Road-bed 8vo, 2 oo
Searles's Field Engineering i6mo, morocco, 3 oo
Railroad Spiral i6mo, morocco i 50
Taylor's Prismoidal Formulae and Earthwork 8vo, i 50
* Trautwine's Method of Calculating the Cubic Contents of Excavations and
Embankments by the Aid of Diagrams 8vo, 2 oo
he .Field Practice of [Laying Out Circular Curves for Railroads.
i2mo, morocco, 2 50
* Cross-section Sheet Paper, 25
^ebb's Railroad Construction. 2d Edition, Rewritten i6mo. morocco, 5 oo
"Wellington's Economic Theory of the Location of Railways Small 8vo, 5 oo
DRAWING.
Barr's Kinematics of Machinery 8vo, 2 50
* Bartlett's Mechanical Drawing 8vo, 3 oo
Coolidge's Manual of Drawing 8vo, paper, i oo
Durley's Kinematics of Machines 8vo, 4 oo
Hill's Text-book on Shades and Shadows, and Perspective 8vo, 2 oo
Jones's Machine Design:
Part I. — Kinematics of Machinery 8vo, i 50
Part II. — Form, Strength, and Proportions of Parts 8vo, 3 oo
MacCord's Elements of Descriptive Geometry 8vo, 3 oo
Kinematics; or, Practical Mechanism 8vo, 5 oo
Mechanical Drawing 4to, 4 oo
Velocity Diagrams 8vo, i 50
* Mahan's Descriptive Geometry and Stone-cutting 8vo, i 50
Industrial Drawing. (Thompson.) 8vo, 3 50
Reed's Topographical Drawing and Sketching 4to, 5 oo
8
Reid's Course in Mechanical Drawing 8vo, 2 oo
Text-book of Mechanical Drawing and Elementary Machine Design. .8vo, 3 oo
Robinson's Principles of Mechanism 8vo, 3 oo
Smith's Manual of Topographical Drawing. (McMillan.) 8vo, 2 50
Warren's Elements of Plane and Solid Free-hand Geometrical Drawing. . i2mo,
Drafting Instruments and Operations i2mo,
Manual of Elementary Projection Drawing i2mo,
Manual of Elementary Broblems in the Linear Perspective of Form and
Shadow i2mo, oo
Plane Problems in Elementary Geometry i2mo, 25
Primary Geometry i2mo, 75
Elements of Descriptive Geometry, Shadows, and.Perspective 8vo, 3 So
General Problems of Shades and Shadows 8vo, 3 oo
Elements of Machine Construction and Drawing 8vo, 7 5°
Problems. Theorems, and Examples in Descriptive Geometrv 8vo, 2 50
Weisbach's Kinematics and the Power of Transmission. (Hermann an''
Klein.) 8vo, 5 oo
Whelpley's Practical Instruction in the Art of Letter Engraving i2mo, 2 oo
Wilson's Topographic Surveying 8vo, 3 So
Free-hand Perspective 8vo, 2 50
Free-hand Lettering. (In preparation.)
Woolf's Elementary Course in Descriptive Geometry Large 8vo, 3 oo
'ELECTRICITY AND PHYSICS.
Anthony and Brackett's Text-book of Physics. (Magie.) Small 8vo, 3 oo
Anthony's Lecture-notes on the Theory of Electrical Measurements 12 mo, i oo
Benjamin'slHistory of Electricity 8vo, 3 oo
Voltaic Cell 8vo, 3 oo
Classen's Quantitative Chemical Analysis by Electrolysis. (Boltwood.). .8vo, 3 oo
Crehore and Squier's Polarizing Photo-chronograph ' 8vo, 3 oo
Dawson's "Engineering" and Electric Traction Pocket-book. . lomo, morocco, 4 oo
blather's Dvnamometers, and the Measurement of Power i2mo, 3 oo
Gilbert's De Magnete. (Mottelay.) 8vo, 2 50
Holman's Precision of Measurements 8vo, 2 oo
Telescopic Mirror-scale Method, Adjustments, and Tests Large 8vo 75
Lanaauer's Spectrum Analysis. (Tingle.) 8vo, 3 oo
Le Chatelier's High-temperature Measurements. (Boudouard — Burgess. )i2mo, 3 OO
Lob's Electrolysis and Electrosynthesis of Organic Compounds. (Lorenz.) i2mo, i oo
* Lyons's Treatise on Electromagnetic Phenomena. Vols. I. and 11. 8vo, each,* 61 oo
* Michie. Elements of Wave Motion Relating to Sound.'and Light 8vo,_£ op
Niaudet's Elementary Treatise on Electric Batteries. (FishoacK. ) i2mo, 2 50
* Parshall and Hobart's Electric Generators Small 4to. half morocco, 10 oo
* Rosenberg's Electrical Engineering. (HaldaneGee — Kinzbrunner.) 8vo, i 50
Ryan, Norris, and Hoxie's Electrical Machinery. (In preparation-'
Thurston's Stationary Steam-engines .^ 8vo, 2 50
* Tillman's Elementary Lessons in Heat 8vo, i 50
Tory and Pitcher's Manual of Laboratory Physics Small 8vo, 2 oo
Ulke's Modern Electrolytic Copper Refining 8vo, 3 oo
LAW.
*iDavis's Elements of Law 8vo, 2 50
* Treatise on the Military Law of United States 8vo, 7 oo
Sheep, 7 So
Manual for Courts-martial i6mo, morocco, i 50
9
Wait's Engineering and Architectural Jurisprudence 8vo, 6 oo
Sheep, 6 50
Law of Operations Preliminary to Construction in Engineering'and Archi- tecture 8vo, 5 oo
Sheep, 5 50
Law of Contracts 8vo, 3 oo
Winthrop's Abridgment of Military Law 12010, a 50
MANUFACTURES.
Bernadou's Smokeless Powder — Nitro-cellulose and Theory of the Cellulose
Molecule i2mo, 2 50
Holland's Iron Founder i2mo, 2 50
" The Iron Founder," Supplement i2mo, 2 50
Encyclopedia of Founding and Dictionary of^Foundry Terms Used.in the
Practice of Moulding i2mo, 3 oo
Eissler's Modern High Explosives 8vo, 4 oo
Effront's Enzymes and their Applications. (Prescott.) 8vo, 3 oo
Fitzgerald's Boston Machinist i8mo, i oo
Ford's Boiler Making for Boiler Makers i8mo, i oo
Hopkins's Oil-chemists' Handbook 8vo, 3 oo
Keep's Cast Iron 8vo, a 50
Leach's The Inspection and Analysis of Food with Specia£Reference to State
Control. (In preparation.)
Metcalf's SteeL A Manual for Steel-users i2mo, 2 oo
Metcalfe's Cost of Manufactures— And the Administration of Workshops,
Public and Private 8vo, 5 oo
Meyer's Modern Locomotive Construction 4to, 10 oo
* Reisig's Guide to Piece-dyeing 8vo, 25 oo
Smith's Press-working of Metals 8vo, 3 oo
Wire: Its Use and Manufacture Small 4to, 3 oo
Spalding's Hydraulic Cement i2mo, 2 oo
Spencer's Handbook for Chemists of Beet-sugar Houses i6mo, morocco, 3 oo
Handbook tor sugar Manufacturers and their Chemists.. . i6mo, morocco, 2 oo Thurston's Manual of Steam-boilers, their Designs, Construction and Opera- tion 8vo, 5 oo
* Walke's Lectures on Explosives 8vo, 4 oo
West's American Foundry Practice I2mo, a 50
Moulder's Text-book i2mo, 2 50
Wiechmann's Sugar Analysis Small 8vo, a 50
Wolff's Windmill as a Prime Mover 8vo, 3 oo
Woodbury's Fire Protection of Mills 8vo, a 50
MATHEMATICS.
Baker's Elliptic Functions 8vo, i 50
* Bass's Elements of Differential Calculus i2mo, 4 oo
Briggs's Elements of Plane Analytic Geometry 12 mo, oo
Chapman's Elementary Course hi Theory of Equations i2mo, 50
Compton's Manual of Logarithmic Computations i2mo, 50
Davis's Introduction to the Logic of Algebra 8vo, 50
* Dickson's College Algebra Large i2mo, 50
* Introduction to the Theory of Algebraic Equations Largeli2mo, 25
Halsted's Elements of Geometry 8vo, 75
Elementary Synthetic Geometry 8vo. 50
10
* Johnson's Three-place Logarithmic Tables: Vest-pocket size paper, ' 15
100 copies for 5 oo
* Mounted on heavy cardboard, 8 X 10 inches, 25
10 copies for 2 oo
Elementary Treatise on the Integral Calculus Small 8vo, i 50
Curve Tracing in Cartesian Co-ordinates izmo, I oo
Treatise on Ordinary and Partial Differential Equations Small 8vo, 3 5<>
Theory of Errors and the Method of Least Squares I2mo, I 50
» Theoretical Mechanics I2mo, 3 oo
Laplace's Philosophical Essay on Probabilities. (Truscott and Emory.) I2mo, 200
* Ludlow and Bass. Elements of Trigonometry and Logarithmic and Other
Tables 8vo, 3 oo
Trigonometry and Tables published separately Each, 2 oo
Maurer's Technical Mechanics. (In preparation.)
Merriman and Woodward's Higher Mathematics 8vo, 5 oo
Merriman's Method of Least Squares 8vo, 2 oo
Rice and Johnson's Elementary Treatise on the Differential Calculus. Sm., 8vo, 3 oo
Differential and Integral Calculus. 2 vols. in one Gziall 8vo, 2 50
Wood's Elements of Co-ordinate Geometry 8vo, 2 oo
Trigonometry: Analytical, Plane, and Spherical i2mo, i oo
MECHANICAL ENGINEERING. MATERIALS OF ENGINEERING, STEAM-ENGINES AND BOILERS.
Baldwin's Steam Heating for Buildings I2mo, 2 50
Barr's Kinematics of Machinery 8vo, 2 50
* Bartlett's Mechanical Drawing 8vo, 3 oo
Benjamin's Wrinkles and Recipes I2mo, 2 oo
Carpenter's Experimental Engineering 8vo, 6 oo
Heating and Ventilating Buildings 8vo, 4 oo
Clerk's Gas and Oil Engine Small 8vo, 4 oo
Coolidge's Manual of Drawing 8vo, paper, i oo
Cromwell's Treatise on Toothed Gearing 1 21x10 , i 50
Treatise on Belts and Pulleys I2mo, i 50
Durley's Kinematics of Machines 8vo, 4 oo
F lather's Dynamometers and the Measurement of Power 12 mo, 3 oo
Rope Driving i2mo, 2 oo
Gill's Gas and Fuel Analysis for Engineers i2mo, i 25
Hall's Car Lubrication I2mo, i oo
Button's The Gas Engine. (In preparation.) Jones's Machine Design:
Part I. — Kinematics of Machinery 8vo, i 50
Part II. — Form, Strength, and Proportions of Parts 8vo, 3 oo
Kent's Mechanical Engineer's Pocket-book i6mo, morocco, 5 oo
Kerr's Power and Power Transmission 8vo, 2 oo
MacCord's Kinematics; or, Practical Mechanism 8vo, 5 oo
Mechanical Drawing 4to, 4 oo
Velocity Diagrams 8vo, i 50
Mahan's Industrial Drawing. (Thompson.) 8vo, 3 50
Poole's Calorific Power of Fuels 8vo, 3 oo
Reid's Course in Mechanical Drawing 8vo. 2 oo
Text-book of Mechanical Drawing and Elementary Machine Design . . 8vo, 3 oo
Richards's Compressed Air 12010, i 50
Robinson's Principles of Mechanism 8vo, 3 oo
Smith's Press-working of Metals 8vo 3 oo
Thurston's Treatise on Friction and Lost Work in Machinery and Mil
Work 8vo, 3 oo
Animal as a Machine and Prime Motor, and the Laws of Energetics . 1 2 mo , i oo
11
Warren's Elements of Machine Construction and Drawing Svo, 7 50
Weisbach's Kinematics and the Power of Transmission. Herrmann —
Klein.) 8vo, 5 oo
Machinery of Transmission and Governors. (Herrmann — Klein.). . Svo, 5 oo
HydrauUcs and Hydraulic Motors. (Du Bois.) 8vo, 5 oo
Wolff's Windmill as a Prime Mover 8vo, 3 oo
Wood's Turbines 8vo, 2 50
MATERIALS OF ENGINEERING.
Bovey's Strength of Materials and Theory of Structures 8vo, 7 50
Burr's Elasticity and Resistance of the Materials of Engineering. 6th Edition,
Reset 8vo, 7 50
Church's Mechanics of Engineering 8vo, 6 oo
Johnson's Materials of Construction . . Large 8vo, 6 oo
Keep's Cast Iron : Svo 2 50
Lanza's Applied Mechanics 8vo, 7 50
Martens's Handbook on Testing Materials. (Henning.) 8vo, 7 50
Merriman's Text-book on the Mechanics of Materials Svo, 4 oo
Strength of Materials i2mo, i oo
Metcalf's Steel. A Manual for Steel-users i2mo. 2 oo
Smith's Wire: Its Use and Manufacture Small 4to, 3 oo
Materials of Machines i2mo, i oo
Thurston's Materials of Engineering 3 vols. , Svo 8 oo
Part II.— Iron and Steel Svo, 3 So
Part IH.— A Treatise on Brasses, Bronzes, and Other Alloys and their
Constituents Svo, 2 50
Text-book of the Materials of Construction Svo 5 oo
Wood's Treatise on the Resistance of Materials and an Appendix on the
Preservation of Timber Svo, 2 oo
Elements of Analytical Mechanics 8vo, 3 oo
STEAM-ENGINES AND BOILERS.
Carnot's Reflections on the Motive Power of Heat. (Thurston.) 12 mo, i 50
Dawson's "Engineering" and Electric Traction Pocket-book. .i6mo, mor., 4 oo
Ford's Boiler Making for Boiler Makers i8mo, i oo
Goss's Locomotive Sparks 8vo, 2 oo
Hemenway's Indicator Practice and Steam-engine Economy i2mo, 2 oo
Button's Mechanical Engineering of Power Plants Svo, 5 oo
Heat and Heat-engines Svo, 5 oo
Kent's Steam-boiler Economy Svo, 4 oo
Kneass's Practice and Theory of the Injector Svo. i 50
MacCord's Slide-valves Svo, 2 oo
Meyer's Modern Locomotive Construction 4to, 10 oo
Peabody's Manual of the Steam-engine Indicator i2mo, i 50
Tables of the Properties of Saturated Steam and Other Vapors Svo, i oo
Thermodynamics of the Steam-engine and Other Heat-engines Svo, 5 oo
Valve-gears for Steam-engines Svo, 2 50
Peabody and Miller's Steam-boilers Svo, 4 oo
Pray'a Twenty Years with the Indicator Large Svo, 2 50
Pupln's Thermodynamics of Reversible Cycles in Gases and Saturated Vapors.
(Osterberg.) i2mo. i 25
Reagan's Locomotives : Simple, Compound, and Electric i2mo, 2 50
Rontgen's Principles of Thermodynamics. (Du Bois.) Svo, 5 oo
Sinclair's Locomotive Engine Running and Management 12 mo, 2 oo
Smart's Handbook of Engineering Laboratory Practice i2mo, 2 50
Snow's Steam-boiler Practice Svo, 3 oo
12
Spangler's Valve-gears 8vo, a 50
Notes on Thermodynamics I2mo, i oo
Spangler, Greene, and Marshall's Elements of Steam-engineering 8vo, 3 oo
Thurston's Handy Tables 8vo. i 50
Manual of the Steam-engine 2 vols.. 8vo 10 oo
Part I. — History, Structuce, and Theory 8vo, 6 oo
Part II. — Design, Construction, and Operation 8vo, 6 oo
Handbook of Engine and Boiler Trials, and the Use of the Indicator and
the Prony Brake 8vo 5 oo
Stationary Steam-engines 8vo, 2 50
Steam-boiler Explosions in Theory and in Practice i2mo, i 50
Manual of Steam-boilers , Their Designs, Construction, and Operation . 8vo, 5 oo
Weisbach's Heat, Steam, a <J Steam-engines. (Du Bois.) 8vo, 5 oo
Whitham's Steam-engine I ^sign 8vo, 5 oo
Wilson's Treatise on Steam-boilers. (Flather.) i6mo, 2 50
Wood's Thermodynamics. Heat Motors, and Refrigerating Machines 8vo, 4 oo
MECHANICS \ND MACHINERY.
Barr's Kinematics ot Machinery 8vo, 2~5O
Bovey's Strength of Materials and Theory of Structures 8vo, 7 50
Chase's The Art of Pattern-making I2mo, 2 SO
Chordal. — Extracts from Letters 12010, 2 oo
Church's Mechanics of Engineering 8vo 6 oo
Notes and Examples in Mechanics 8vo. 2 oo
Compton's First Lessons in Metal-working i amo, i 50
Compton and De Groodt's The Speed Lathe I2mo, I 50
Cromwell's Treatise on Toothed Gearing I2mo, I 50
Treatise on Belts and Pulleys I2mo, i 50
Dana's Text-book of Elementary Mechanics for the Use of Colleges and
Schools i2mo, i 50
Dingey's Machinery Pattern Making I2mo, a oo
Dredge's Record of the Transportation Exhibits Building of the World's
Columbian Exposition of 1893 4to, half morocco, 5 oo
Du Bois's Elementary Principles of Mechanics:
Vol. I. — Kinematics 8vo, 3 50
Vol. II. — Statics 8vo, 4 oo
Vol. III. — Kinetics 8vo, 3 50
Mechanics of Engineering. Vol. I .Small 4to, 7 50
VoL H Small 4to, 10 oo
Durley's Kinematics of Machines 8vo, 4 oo
Fitzgerald's Boston Machinist i6mo, I oo
Flather's Dynamometers, and the Measurement of Power lamo, 3 oo
Rope Driving 1 2mo , 2 oo
Goss'g Locomotive Sparks 8vo, 2 oo
Hall's Car Lubrication I2mo, I oo
Eolly's Art of Saw Filing i8mo 75
* Johnson's Theoretical Mechanics 1 2mo, 3 oo
Statics by Graphic and Algebraic Methods 8vo, 2 oo
Jones's Machine Design:
Part I. — Kinematics of Machinery 8vo, i 50
Part II. — Form, Strength, and Proportions of Parts 8vo, 3 oo
Kerr's Power and Power Transmission 8vo, a oo
Lanza's Applied Mechanics 8vo, 7 50
MacCord's Kinematics; or, Practical Mechanism 8vo, 5 oo
Velocity Diagrams 8ro, I 50
Maurer's Technical Mechanics. (In preparation.)
13
Merriman's Text-book on the Mechanics of Materials 8vo, 4 oo
* Michie's Elements of Analytical Mechanics Svo, 4 oo
Reagan's Locomotives: Simple, Compound, and Electric izmo, 2 50
Reid's Courselin Mechanical Drawing 8vo, 2 oo
Text-book ofMechanical Drawing and Elementary Machine Design . . 8vo, 3 oo
Richards's Compressed Air i2mo, i 50
Robinson's Principles of Mechanism 8vo, 3 oo
Ryan, Norris, and Hoxie's Electrical Machinery. (In preparation.)
Sinclair's Locomotive-engine Running and.Management • i2mo, 2 oo
Smith's Press-working of Metals 8vo, 3 oo
A Materials of Machines i2mo, i oo
Spangler, Greene, and Marshall's Elements of Steam-engineering 8vo, 3 oo
Thurston's Treatise on Friction and Lost Work in Machinery and Mill
Work 8vo, 3 oo
Animal as a Machine and Prime Motor, and the Laws of Energetics. i2mo, i oo
Warren's Elements of Machine Construction and Drawing 8vo, 7 50
Weisbach's Kinematics I and the Power of Transmission. (Herrmann —
Klein.) 8vo, 5 oo
Machinery of Transmission and Governors. (Herrmann — Klein. ).8vo, 5 oo
Wood's Elements of Analytical Mechanics 8vo, 3 oo
Principles of Elementary Mechanics i2mo, i 25
Turbines 8vo, 2 50
The World's Columbian Exposition of 1893 4to, i oo
METALLURGY.
Egleston's Metallurgy of Silver, Gold, and Mercury:
Vol. I.— Silver 8vo, 7 50
Vol. II. — Gold and Mercury 8vo, 7 50
** Iles's Lead-smelting. (Postage 9 cents additional.) i2mo, 2 50
Keep's Cast Iron 8vo, 2 50
Kunhardt's Practice of Ore Dressing in Europe 8vo, i 50
Le Chatelier's High-temperature Measurements. (Boudouard — Burgess.) . i2mo, 3 oo
Metcalf 's Steel. A Manual for Steel-users i2mo, 2 oo
Smith's Materials of Machines i2mo, i oo
Thurston's Materials of Engineering. In Three Parts 8vo, 8 oo
Part II. — Iron and Steel 8vo, 3 50
Part III. — A Treatise on Brasses, Bronzes, and Other Alloys and their
Constituents 8vo, 2 50
Ulke's Modern Electrolytic Copper Refining 8vo, 3 oo
MINERALOGY.
Barringer's Description of Minerals of Commercial Value. Oblong, morocco, 2 50
Boyd's Resources of Southwest Virginia 8vo," 3 oo
Map of Southwest Virginia Pocket-book form, 2 oo
Brush's Manual of Determinative Mineralogy. (Penfield.). 8vo, 4 oo
Chester's Catalogue of Minerals 8vo, paper, i oo
Cloth, i 25
Dictionary of the Names of Minerals 8vo, 3 50
Dana's System of Mineralogy Large 8vo, half leather, 12 50
First Appendix to Dana's New "System of Mineralogy." Large 8vo, i oo
Text-book of Mineralogy 8vo, 4 oo
Minerals and How to Study Them 121110, i 50
Catalogue of American Localities of Minerals Large 8vo, i oo
Manual of Mineralogy and Petrography i2mo, 2 oo
Egleston's Catalogue of Minerals and Synonyms 8vo, 2 50
Hussak's The Determination of Rock-forming Minerals. (Smith.) Small 8vo, 2 oo
14
* Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests.
8vo, paper, o 50 Rosenbusch's Microscopical Physiography of the Rock-making Minerals.
(Iddings.) 8vo, 5 oo
* Tillman's Text-book of Important Minerals and Docks 8vo, 2 oo
Williams's Manual of Lithology 8vo, 3 oo
MINING.
Beard's Ventilation of Mines i2mo, 2 50
Boyd's Resources of Southwest Virginia 8vo, 3 oo
Map of Southwest Virginia Pocket-book form, 2 oo
* Drinker's Tunneling, Explosive Compounds, and Rock Drills.
4to, half morocco, 25 oo
Eissler's Modern High Explosives 8vo, 4 oo
Fowler's Sewage Works Analyses Z2mo, oo
Goodyear's Coal-mines of the Western Coast of the United States 12010, 50
Ihlseng's Manual of Mining . , 8vo, oo
** Iles's Lead-smelting. (Postage QC. additional.) I2mo, 50
Kunhardt's Practice of Ore Dressing in Europe 8vo, 50
O'Driscoll's Notes on the Treatment of Gold Ores 8vo, oo
* Walke's Lectures on Explosives 8vo, oo
Wilson's Cyanide Processes I2mo, 50
Chlorination Process i2mo, 50
Hydraulic and Placer Mining 12010, oo
Treatise on Practical and Theoretical Mine Ventilation 12 mo, 25
SANITARY SCIENCE.
Copeland's Manual of Bacteriology. (In preparation.)
Folwell's Sewerage. (Designing, Construction, and Maintenance.; 8vo, 3 oo
Water-supply Engineering 8vo, 4 oo
Fuertes's Water and Public Health 1 2 mo, i 50
Water-filtration Works I2mo, 2 50
Gerhard's Guide to Sanitary House-inspection i6mo, i oo
Goodrich's Economical Disposal of Town's Refuse Demy 8vo, 3 50
Hazen's Filtration of Public Water-supplies 8vo, 3 oo
Kiersted's Sewage Disposal i2mo, i 25
Leach's The Inspection and Analysis of Food with Special Reference to State
Control. (In preparation.')
Mason's Water-supply. (Considered Principally from a Sanitary Stand- point.) 3d Edition, Rewritten 8vo, 4 oo
Examination of Water. (Chemical and Bacteriological.) i2mo, I 25
Merriman's Elements of Sanitary Engineering 8vo, 2 oo
Nichols's Water-supply. (Considered Mainly from a Chemical and Sanitary
Standpoint.) (1883.) 8vo, 2 50
Ogden's Sewer Design 1 2010, 2 oo
* Price's Handbook on Sanitation I2mo, i 50
Richards's Cost of Food. A Study in Dietaries i2mo, i oo
Cost of Living as Modified by SanitarylScience 12 mo, i oo
Kichards and Woodman's Air, Water, and Food from a Sanitary Stand- point 8vo, 2 oo
* Richards and Williams's The Dietary'Computer 8vo, i 50
Rideal's Sewage and Bacterial Purification of Sewage 8vo, 3 50
Turneaure and Russell's Public Water-supplies 8vo, 5 oo
Whipple's Microscopy of Drinking-water 8vo, 3 50
Woodhull's Notes'and Military Hygiene i6mo, i 50
15
MISCELLANEOUS.
Barker's Deep-sea Soundings 8vo, 2 oo
Emmons's Geological Guide-book of the Rocky Mountain Excursion of the
International Congress of Geologists Large 8vo, i 50
FerrePs Popular Treatise on the Winds 8vo, 4 oo
Haines's American Railway Management i2mo, 2 50
Mott's Composition.'Digestibility , and Nutritive Value of Food. Mounted chart, i 25
Fallacy of the Present Theory of Sound i6mo, i oo
Ricketts's History of Rensselaer Polytechnic Institute, 1824-1894. Small 8vo, 3 oo
Rotherham's Emphasized New Testament Large 8vo, 2 oo
Steel's Treatise on the Diseases of the Dog 8vo, 3 50
Totten's Important Question in Metrology 8vo, 2 50
The World's Columbian Exposition of 1893 4to, i oo
Worcester and Atkinson. Small Hospitals, Establishment and Maintenance, and Suggestions for Hospital Architecture, with Plans for a Small
Hospital I2mo, i 25
HEBREW AND CHALDEE TEXT-BOOKS.
Green's Grammar of the Hebrew Language 8vo, 3 oo
Elementary Hebrew Grammar i2mo, i 25
Hebrew Chrestomathy 8vo, 2 oo
Gesenius's Hebrew and Chaldee Lexicon to the Old Testament Scriptures.
(Tregelles.) Small 4to, half morocco, 5 oo
Letteris's Hebrew Bible 8vo, 2 25
16
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