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THE ELEMENTS OF BLOWPIPE ANALYSIS
THE
ELEMENTS OF BLOWPIPE ANALYSIS
BY
FREDERICK HUTTON GETMAN, F.C.S.
INSTRUCTOR IN CHEMISTRY IN THE STAMFORD HIGH SCHOOL
godt THE MACMILLAN COMPANY
LONDON : MACMILLAN & CO., LTD. 1899
All rights reserved
BY THE MACMILLAN COMPANY.
Nortoonfi J. 8. Gushing & Co. - Berwick Sc Smith Norwood Mass. U.S.A.
PREFACE
THESE few pages are intended to serve a twofold purpose, — to give the student a general outline of Blowpipe Analysis, and to introduce him to the methods of Determinative Mineralogy.
Every effort has been made to simplify details so that the book may be used in both High Schools and Colleges.
Tables for " systematic " examination have been intentionally omitted, for in the au- thor's estimation these tend to dull the student's power of observation, and to make him place little value upon minute details.
The alphabetic arrangement has been followed for the sake of convenience when referring to the book.
819488
Vi PREFACE
The last chapter is not intended to serve as a key to determining the minerals therein described, but rather it is added to give the student exercise in Blowpipe Analysis, and at the same time to point out the methods of Determinative Mineralogy.
Finally, the author would acknowledge his indebtedness to the following works : " Man- ual of Qualitative Analysis," Fresenius; "Qualitative Chemical Analysis," Venable; Roscoe and Schorlemmer's " Treatise on Chemistry"; Foye's " Hand- Book of Min- eralogy"; Dana's "Mineralogy"; Kobell's "Tafeln zur Bestimmung der Mineralien";
etc.
FREDERICK HUTTON GETMAN.
STAMFORD, CONN., Feb. 22, 1899.
TABLE OF CONTENTS
CHAPTER I
PAGE
Apparatus and Reagents 1-7
CHAPTER II
General Outline of Blowpipe Analysis 8
Definitions 9
Examination on Charcoal Alone 10
Examination on Charcoal with Sodium Carbonate . . 13
Examination in Tube with Sodium Carbonate and Charcoal . 15
Examination on Platinum Wire 16
Examination in Borax Bead 17
Examination with Cobalt Nitrate 20
CHAPTER III
General Reactions for the Detection of the Metallic Ele- ments in Simple Compounds 22
Aluminum 23
Antimony 24
Arsenic 25
Bismuth - • • . ' , 25
Cadmium 26
Chromium 26
Cobalt .......... 27
vii
viii CONTENTS
PAGE
Copper 28
Iron 28
Lead 29
Manganese 30
Mercury 30
Nickel 31
Silver 32
Tin 32
Zinc 33
The Alkali Metals 34
Ammonium 34
Potassium 35
Sodium 35
Lithium 36
The Alkaline Earths 36
Barium 36
Calcium 37
Strontium 37
The Acid Elements
37
Borates 37
Bromides 38
Chlorides 38
Fluorides 38
Iodides 39
Nitrates 39
Phosphates 40
Silicates . . . .40
Sulphides . .41
CONTENTS IX CHAPTER IV
PAGE
Behavior of Some of the Principal Ores before the Blowpipe 43
Ores of Antimony •••'.. . . 46
Ores of Arsenic . . . . "* . . . -47
Ores of Bismuth . » , . . . . . . 48
Ores of Chromium 49
Ores of Cobalt 50
Ores of Copper , , 52
Ores of Iron 57
Ores of Lead 60
Ores of Manganese 63
Ores of Mercury 64
Ores of Nickel 65
Ores of Silver 66
Ores of Tin i . . 69
Ores of Zinc 70
COMPARATIVE TABLES
I. Colors of Coatings on Charcoal 73
II. Flame Colorations , •' 9 73
III. Colors of Borax Beads in oxidizing Flame ... 74
IV. Colors of Borax Beads in reducing Flame ... 75 V. Colors of Microcosmic Salt Beads in oxidizing Flame . 76
VI. Colors of Microcosmic Salt Beads in reducing Flame . 77
FORCEPS Fig. 5
AGATE MORTAR & PESTLE Fig. 4
HAMMER Fig, 6,
3 -CORNERED FIJ_ES Fig, 7
BLOWPIPE ANALYSIS
CHAPTER I
THE blowpipe was first applied to mineral analysis in 1733 by Anton Swab, and its applications have since been improved and extended by various chemists, among whom may be mentioned Bergmann, Cronstedt, Gahn, Berzelius, and Plattner.
Blowpipe. — The common blowpipe of the jeweller is not particularly well suited to the operations of blowpipe analysis, since the flame has often to be kept playing upon the assay for some time, and the condensed moisture of the breath would seriously interfere with the passage of the
« BLOWPIPE ANALYSIS
air through the jet. One of the best and least expensive forms of blowpipe is shown in Fig. i. This consists, as is seen from the illustration, of a conical-shaped tube of tin closed at the wide end and formed into a mouthpiece at the small end; soldered into the tube at the large end, and at right angles to its axis, is a small brass tube which terminates in a conical tip pierced with a very fine hole. With this pipe it is possible to perform all of the operations of mineral analysis.
Some little practice is necessary to keep the flame steady and to take the breath at the same time.
No rule can well be given to the begin- ner, but his experience becomes his best guide.
Bunsen Flame. — Any kind of flame can be used for the blowpipe, provided it be
BUNSEN FLAME 3
not too small ; but since almost every labo- ratory to-day is furnished with gas and the Bunsen burner (Fig. 2), it will only be necessary to describe the use of the flame from this source. Upon examining the Bunsen flame with care, it will be seen that the flame consists of three distinct parts.
A dark inner cone which consists of gas not yet raised to the ignition point. Be- yond this there is a luminous cone, where combustion is incomplete owing to lack of oxygen, and outside of this we find the non-luminous cone where the gas is com- pletely burned.
This outer envelope is the hottest por- tion of the flame, and is known as the " oxidizing " flame because there is an excess of oxygen which is imparted to substances placed therein.
The luminous cone is known as the "reducing" flame, for in it metallic oxides
4 BLOWPIPE ANALYSIS
are reduced, the oxygen being taken up by the small incandescent particles of car- bon.
If the air-holes at the base of the Bun- sen burner be opened, the two inner cones become elongated, and the flame appears almost colorless.
The blowpipe enables us to get an oxidiz- ing and a reducing flame of better form and greater power. To do this we cut off the air supply at the base of the burner and turn off the gas until the flame is about i cm. high; then upon introducing the blowpipe, and blowing a strong con- tinuous jet of air across the Bunsen flame, we produce an oxidizing flame about 4-5 cm. in length. If the tip of the blowpipe be held outside of the Bunsen flame, and the pressure of the stream of air be dimin- ished, we obtain a reducing flame.
BUNSEN FLAME 5
Supports. — For supports, charcoal, plati- num, and glass are chiefly used. The charcoal should be made from some light wood, such as alder. It should be well burnt, and should not scintillate or smoke.
The platinum supports are generally in the form of wire and foil. Platinum-tipped forceps are frequently employed in blow- pipe analysis.
Glass is used in the form of tubing.
Hard glass tubing, 3 mm. bore, is drawn off into ignition tubes 7-8 cm. in length. Several dozen of these tubes should be made before commencing the tests of the next chapter.
Apparatus. — A small agate mortar, 4-5 cm. in diameter, should be provided in which to grind the samples to be exam- ined.
The pestle, which should also be of agate,
6 BLOWPIPE ANALYSIS
must be adapted to the mortar in shape and size.
Two pairs of forceps will also be needed.
One pair should be of steel, and the other pair of brass, with fine points.
Of other apparatus, the most necessary is: —
A small hammer and anvil.
Two three-cornered files.
Small piece of cobalt glass, about 5 x 10 cm.
Pocket magnifying lens.
Several small watch glasses — for metallic beads, etc.
Chemicals. — A list of the principal chemi- cals is here given : —
Sodium carbonate, Na2CO3.
Borax, Na2B4O7+ ioH2O.
Microcosmic salt, (HNaNH4), PO4 + 8 H2O.
BUNSEN FLAME 7
Cobalt nitrate, Co(NO3)2+5 H2O. Potassium cyanide, KCN. Hydrochloric acid, (dilute), HCl + nH2O. Litmus paper, red and blue. Brazil-wood paper.
Any other special reagents which may be needed will be mentioned as required.
CHAPTER II
GENERAL OUTLINE OF BLOWPIPE ANALYSIS
[ABBREVIATIONS : O. F. for oxidizing flame, R. F. for reducing flame, Ch. for charcoal, Ct. for coating, Bp. for blowpipe.]
IN order to examine a substance before the blowpipe to determine the presence or absence of certain elements, it becomes necessary to arrange a systematic method. As with all branches of chemical work, one's success is largely dependent upon neatness of manipulation and carefulness of observation.
The following order of observation is essentially that given by Berzelius : —
1. Examination on charcoal by itself.
2. Examination on charcoal with NazCO3.
8
GENERAL OUTLINE OF BLOWPIPE ANALYSIS 9
3. Examination in ignition tube with Na2CO8 and charcoal.
4. Examination on platinum wire.
5. Examination in borax bead.
6. Examination with Co(NO3)2.
After having examined a body in these six different ways, we shall be able to say what are its principal constituents.
Before describing the method of carrying out these six different operations, it will be necessary to give a few definitions of terms which we shall have frequent occasion to employ.
Definitions. — Ignition is the heating of a substance to a high temperature.
Fusion is the heating of a substance to the melting-point.
Intumescence is the swelling of the sub- stance upon heating.
10 BLOWPIPE ANALYSIS
Decrepitation is the crackling of a sub- stance due to the sudden expansion of combined water upon heating.
Deflagration is the burning of a sub- stance with explosive violence, generally due to excess of oxygen.
Incandescence is the white light emitted by a substance that is infusible when sub- jected to a high temperature.
Examination on Charcoal alone. — The size of the assay should be about that of a mustard seed. This is sufficiently large to show all of the reactions clearly, and though a larger piece would exhibit the character- istic phenomena, yet much more effort is required. A very small, shallow hole should be cut in the Ch. to receive the assay. The Bp. flame should be directed at an angle of about 30° with the surface of the Ch. Con- siderable care must be taken lest the hole in
GENERAL OUTLINE OF BLOWPIPE ANALYSIS II
the Ch. is burned too deep and the assay lost in the coal.
The force of the air from the jet must also be borne in mind for a strong blast, or sudden puffs may blow the substance away.
The following changes are to be looked for: —
a. Whether the substance is volatile or non-volatile.
Illustrations. Examine before the Bp. on Ch. some arsenious oxide, As2O3, also some alumina, A12O3.
b. Whether the substance is fusible or infusible.
Illustrations. Examine before the Bp. on Ch. some silver oxide, AgO, also some zinc oxide, ZnO.
c. Whether the substance is alkaline or non-alkaline when placed upon moistened red litmus.
12 BLOWPIPE ANALYSIS
Illustrations. Ignite some calcium car- bonate, CaCO3, before the Bp. on Ch., and place residue on moistened red litmus. In like manner, examine some magnesium car- bonate, MgCO3.
d. Color of coating on Ch. caused by combination of metal and oxygen due to heat of Bp. flame.
Illustrations. Examine some oxide of lead, PbO, before the Bp. on Ch., also some oxide of cadmium, CdO.
e. Decrepitation.
Illustration. Examine some sodium chlo- ride, NaCl, before the Bp. on Ch.
f. Deflagration.
Illustrations. Examine some potassium nitrate, KNO3, before the Bp. on Ch., also some ammonium nitrate, NH4NO3.
GENERAL OUTLINE OF BLOWPIPE ANALYSIS 13
g. Intumescence.
Illustration. Examine some alum,
K2A12(S04)4, • :
before the Bp. on Ch.
h. Incandescence.
Illustration. Examine some oxide of barium, BaO, before the Bp. on Ch.
i. Formation of a metallic bead — color and malleability.
Illustration. Examine some silver oxide, AgO, before the Bp. on Ch.
Examination on Charcoal with Na2C03. —
Metallic compounds are often difficult to reduce with the blowpipe flame alone, and hence no bead is obtained. In order to facilitate reduction and the obtaining of a metallic bead, the substance in a finely powdered condition is mixed with four
14 BLOWPIPE ANALYSIS
parts of sodium carbonate, Na2CO3, and ignited before the Bp. on Ch. The me- tallic compound is decomposed, the metal being transformed into the carbonate, which in turn, through the agency of the Ch. and the heat of the flame, is reduced to the free metal. Sometimes the reduction is made easier by adding to the substance about its own bulk of potassium cyanide, KCN, which takes up oxygen from the compound and is converted into potassium cyanate, KCNO.
The reactions in reducing copper sul- phate, CuSO4, with Na2CO3 and with KCN before the blowpipe, are here given : —
CuS04 + Na2C03 = CuC03 + Na2SO4 1 2 CuCO3 + C = 3 CO2 + 2 Cu J
CuSO4 + Na2CO3 = CuCO8 + Na2SO4 CuO + KCN = Cu + KCNO
GENERAL OUTLINE OF BLOWPIPE ANALYSIS 15
After obtaining beads, it is well to obtain their coatings, for oftentimes it is only in this way that we can distinguish between the metals.
Examination in Tube with Na2C03 and Charcoal. — If the substance in a finely pulverized condition be mixed with twelve parts, Na2CO3, and six parts of charcoal powder and the mixture be placed in an ignition tube and subjected to heat, the acid of the substance combines with the soda and the metal is set free.
If this metal is volatile, a sublimate is formed in the upper end of the tube.
Mercury deposits in minute globules, which may be seen with the magnifying glass. Arsenic forms a ring, which, when examined with the magnifying glass, is seen to be made up of minute crystals. Am- monia is recognized by its characteristic
1 6 BLOWPIPE ANALYSIS
odor, and also by its turning a slip of moistened red litmus (held over the mouth of the tube) blue.
Examination on Platinum Wire. — Many substances possess the property of impart- ing to the colorless flame of the Bunsen burner characteristic colors.
The chlorides of these substances exhibit these flame reactions best, and hence before applying the flame tests we dip the wire which serves as a support into hydrochloric acid and then into the substance. When the substance has been taken up on the wire, it is placed in the edge of the long colorless flame of the Bunsen burner near the apex, when instantly the flame becomes tinged with the characteristic color of the substance.
Illustrations. Sodium compounds color the flame yellow, and a crystal of potas-
GENERAL OUTLINE OF BLOWPIPE ANAL YSIS I /
sium dichromate appears colorless in the sodium light.
This sodium reaction is extremely deli- cate, it being possible to detect with ease a quantity of a sodium salt less than innnhnnr of a milligram in weight.
Potassium colors the flame purplish-violet.
Barium colors the flame apple-green.
Strontium colors the flame crimson.
Calcium colors the flame orange-red, dis- tinguished from strontium, by appearing gray when seen through blue glass.
Boracic acid colors the flame green when the substance has been moistened with glycerine.
Examination in Borax Bead. — Borax, Na2B4O7, and microcosmic salt,
NaNH4H . P04, possess the property of dissolving many of
1 8 BLOWPIPE ANALYSIS
the metallic oxides at the temperature of the Bunsen flame.
For example, with oxide of cobalt, the following reactions take place with the two fluxes : —
CoO + Na2B4OT = Co(BO2)2 + 2 NaBO2.
On heating, NaNH4H.PO4, it is decom- posed into the metaphosphate of sodium, NaPO8,
CoO + NaPO3 = CoNaPO4.
Now in such cases of solution the me- tallic oxides impart a characteristic color to the flux.
The platinum wire is the best support, — it is heated to incandescence in the Bunsen flame, and then is quickly dipped into the borax, when a small globule will adhere, — this is removed to the flame again when the borax melts to a clear glassy bead. While the bead is still melted, touch it to
GENERAL OUTLINE OF BLOWPIPE ANALYSIS 1 9
the finely pulverized substance and replace in the flame. In a few seconds the small particles of the substance will have dis- solved, and the bead will be seen to have assumed the color characteristic of the sub- stance. Note the color when hot and then when cold ; often there is a wide difference. Then, too, the test should be made in both O. F. and R. F.
Some analysts prefer to make a small loop in the end of the wire before taking up the borax to make the bead. Care should be taken to see that the bead is colorless before bringing it in contact with the substance.
As the depth of color produced is largely dependent upon the amount of substance taken, some little caution should be exer- cised to insure taking up about the same quantity each time.
Illustrations. Make several beads, and
20 BLOWPIPE ANALYSIS
note the colors characteristic of the follow- ing oxides: cobalt, nickel, iron, manganese, chromium, and copper.
The microcosmic salt bead dissolves al- most every oxide except silica, SiO2, and this is seen to float about in the melted mass. This is used as a test for silica.
Examination with Co(N03)2. — If after ex- amination on the Ch. per se, a white infusible residue remains, it is moistened with a drop of cobalt nitrate Co(NO3)2 and re-ignited before the Bp., when a change of color will be observed. This change in color is owing to the fact that the heat of the Bp. flame decomposes the cobalt nitrate, nitric acid being driven off, and the remaining CoO forming with the oxide of the residue a colored mass.
Illustrations. Ignite before the Bp. on Ch. the following oxides, — allow to cool,
GENERAL OUTLINE OF BLOWPIPE ANALYSIS 21
add a drop of Co(NO8)2, re-ignite, and note color, — aluminum, magnesium, zinc, and calcium.
Care should be taken to thoroughly ignite before adding the cobalt nitrate solution.
With the six methods of examination just given almost every simple substance can be detected, but should any doubt remain, a few simple tests in the " liquid way " will be sufficient to substantiate the blowpipe exam- ination.
CHAPTER III
GENERAL REACTIONS FOR THE DETECTION OF THE METALLIC ELEMENTS IN SIMPLE COMPOUNDS
FOR the sake of convenience, rather than for scientific reasons, the following com- pounds have been arranged in alphabetic order. Also the oxides of the elements have been taken, since they exhibit the reactions to best advantage.
The student should work through care- fully each one of the tests and satisfy him- self as to the characteristic reactions of the various elements, for only in this way can he expect to recognize the substances when presented to him as " unknowns." It is advisable to provide a note-book and rule it as follows : —
22
GENERAL REACTIONS
|
BEHAVIOR OF SUBSTANCE |
|||||
|
Before Bp. onCh. alone |
Before Bp. on Ch. with NajCO8 |
In ignition tube with Na2CO3and Ch. |
In flame on platinum wire |
In flame with borax bead |
After first ignition with Co(NO3)2 |
|
- |
|||||
|
Remar Substa |
ks |
||||
|
nee __ |
|||||
i. Aluminum, AL03. — Before the Bp. on Ch. Infusible. No change.
Before the Bp. on Ch. with Na2CO8. Forms an infusible compound with slight intumescence.
In ignition tube with Na2CO3 and Ch. No change. Moisture driven off.
In flame on platinum wire. No change. Becomes incandescent.
In flame with borax bead. In O. F.
24 BLOWPIPE ANALYSIS
dissolves slowly, forming a colorless glass which remains so on cooling.
With Co(NO3)2. Mass becomes blue upon re-ignition.
2. Antimony, Sb203. — Before the Bp. on Ch. In O. F. volatilizes without change. In R. F. is reduced and volatilized. White coating of antimonious oxide deposited on Ch. Blue tinge imparted to flame.
Before the Bp. on Ch. with Na2CO3. Readily reduced. ' White brittle bead. Very volatile, giving characteristic white coat- ing.
In ignition tube with Na2CO3 and Ch. Volatilized.
In flame on platinum wire. Volatilized. Colors flame greenish blue.
With borax bead on platinum wire. In O. F. dissolves to a colorless glass.
With Co(N03)2
GENERAL REACTIONS 2$
3. Arsenic, As203. — Before the Bp. on Ch. Very volatile. Strong garlic odor to fumes.
Before the Bp. on Ch. with Na^COs. Reduced with emission of arsenical fumes.
In ignition tube with Na2CO3 and Ch. Volatilizes, forming a mirror-like deposit of metallic As in the cooler part of tube.
In flame on platinum wire
With borax bead on platinum wire
With Co(N03)2_.
4. Bismuth, Bi203. — Before the Bp. on Ch. Yields a coating — orange-yellow when hot, lemon-yellow when cold. The yellow coating usually has a white outline.
Before the Bp. on Ch. with Na2CO3. Easily reduced to metallic bismuth. Yellow bead brittle, but less so than antimony.
In ignition tube with Na2CO3 and Ch.
26 BLOWPIPE ANALYSIS
In flame on platinum wire
With borax bead on platinum wire. In O. F. small quantity dissolves to a clear yellow glass, which becomes colorless when cold
With Co(NO3)2 _.. ._
5. Cadmium, CdO. — Before the Bp. on Ch. Gives a coating on the coal. Red- dish-brown when cold. Very volatile.
Before the Bp. on Ch. with Na2CO3. Readily reduced. The metal volatilizes easily, giving the characteristic coating.
In ignition tube with Na2CO3 and Ch.
In flame on platinum wire
With borax bead. In O. F. dissolves to a clear yellowish bead, colorless when cold. With Co(N08)2
6. Chromium, Cr203. — Before the Bp. on Ch. No change.
GENERAL REACTIONS 2/
Before the Bp. on Ch. with Nc^COg. Cannot be reduced. Soda sinks in Ch. and a green colored mass remains.
In ignition tube with Na2CO3 and Ch.
In flame on platinum wire
With borax bead. Dissolves slowly but colors intensely. Yellow while hot, green when cold.
With microcosmic salt bead. Colors red when hot, green when cold.
With Co(NO3)2
7. Cobalt, CoO. — Before the Bp. on Ch. In O. F. unchanged. In R. F. is reduced to the metal and is magnetic.
Before the Bp. on Ch. with Na^COg. Reduced to a gray magnetic mass.
In ignition tube with Na^COa and Ch.
In flame on platinum wire
28 BLOWPIPE ANALYSIS
With borax bead on platinum wire. In O. F. colors very intensely blue, both hot and cold.
With Co(NO3)2
8. Copper, CuO. — Before the Bp. on Ch. Fuses to a black globule, which can be reduced with some difficulty.
Before the Bp. on Ch. with Na2CO3. Readily reduced to metallic bead, which is red in color, hard, malleable.
In ignition tube with Na2CO3 and Ch.
In flame on platinum wire. Colors flame emerald-green.
With borax bead on platinum wire. In O. F. green when hot, blue when cold.
With Co(N03)2
9. Iron, Fe203. — Before the Bp. on Ch. In O. F. unchanged. In R. F. becomes black and magnetic.
GENERAL REACTIONS 29
Before the Bp. on Ch. with Na2CO3 Reduced to a metallic powder, magnetic. In ignition tube with Na2CO3 and Ch.
In flame on platinum wire
With borax bead on platinum wire. In O. F. red while hot, yellow when cold. With Co(NO3)2
10. Lead, PbO. — Before the Bp. on Ch. Easily reduced to the metal, bead very malleable. Coating yellow, surrounded by white ring.
Before the Bp. on Ch. with Na^COg. Instantly reduced. Coats the Ch. upon further blowing.
In ignition tube with Na2CO3 and Ch. Reduced to the metal.
In flame on platinum wire. Tinges flame blue.
With borax bead on platinum wire.
30 BLOWPIPE ANALYSIS
In O. F. dissolves easily, forming a limpid glass.
With Co(N03)2
11. Manganese, Mn203. — Before the Bp. on Ch. At high temperature turns red.
Before the Bp. on Ch. with Na2CO3. Is not reduced.
Before the Bp. in O. F. on platinum foil with -NagCOg. Transparent green mass when hot. Opaque, bluish-green when cold.
In ignition tube with Na2CO3 and Ch. Not reduced.
In flame on platinum wire
With borax bead on platinum wire. In O. F. violet-red while hot, amethyst-red when cold.
With Co(N03)2
12. Mercury, HgO. — Before the Bp. on Ch. Instantly reduced. Very volatile.
Before the Bp. on Ch. with Na2CO3. Re- duced and volatilized.
GENERAL REACTIONS 31
In ignition tube with Na.2CO3 and Ch. Sublimes condensing in the upper part of the tube as a metallic ring which is seen with the lens to consist of minute globules of mercury.
In flame on platinum wire
With borax bead on platinum wire
WithCo(N03)2__
13. Nickel, NiO. — Before the Bp. on Ch. In O. F. unchanged. In R. F. reduced to metal, slightly magnetic.
Before the Bp. on Ch. with Na2CO8. Easily reduced to the metal.
In ignition tube with Na2CO3 and Ch.
In flame on platinum wire
With borax bead on platinum wire. In O.F. violet while hot, reddish-brown when cold. With Co(NO3)2._
32 BLOWPIPE ANALYSIS
14. Silver, AgO. — Before the Bp. on Ch. Easily reduced to the metal. White, mal- leable, hard bead. Coats the coal dark red near assay.
Before the Bp. on Ch. with Na2CO3. In- stantly reduced to metallic globule.
In ignition tube with Na2CO3 and Ch. Reduced to the metal.
In flame on platinum wire
With borax bead on platinum wire. In O. F. partially dissolved. Bead becomes milk-white.
With Co(NO3)2
15. Tin, Sn02. — Before the Bp. on Ch. Coats the coal yellow while hot, dirty white when cool. Not reduced.
Before the Bp. on Ch. with Na2CO3. Re- duced to metallic tin. White, hard, mal- leable bead. Coating white and close to assay.
GENERAL REACTION'S 33
In ignition tube with Na2CO8 and Ch.
In flame on platinum wire
With borax bead on platinum wire. In
O. F. small quantity dissolves to limpid
glass.
With Co(NO3)2. Greenish-blue color.
1 6. Zinc, ZnO. — Before the Bp. on Ch.
Upon ignition becomes yellow. Is not reduced.
Before the Bp. on Ch. with Na2CO3. Re- duced to metal. Rapidly volatilized, coating the coal white.
In ignition tube with Na2CO3 and Ch.
In flame on platinum wire
With borax bead on platinum wire. In O.F. yellow while hot, limpid glass when cold.
*
With Co(NO3)2. Green mass.
34 BLOWPIPE ANALYSIS
Having now given the principal reactions for the most important metals, we will pro- ceed to the examination of the alkali metals, the alkaline earths, and some of the acid elements.
THE ALKALI METALS
17. Ammonium, NH4. — This hypotheti- cal compound is commonly classed among the alkali metals from its close resemblance to the members of this group.
To detect the presence of this hypotheti- cal metal, mix the assay with about four parts of Na2CO3, place in an ignition tube, and apply heat. The odor of the evolved gas will be recognized, and if a piece of red litmus paper be moistened and held at the mouth of the tube, it will be turned blue by the escaping ammonia gas.
We are not authorized to infer the pre- existence of ammonium, however, from the
GENERAL REACTIONS 3$
appearance of this reaction, for the pres- ence of nitrogenous organic matter in the substance, which would be decomposed by this treatment, would give rise to such a reaction.
1 8. Potassium. — Potassium is recognized by the color which its salts impart to the Bunsen flame. If a portion of a salt of potassium be held on a platinum wire in the flame, it imparts a blue-violet tint which rapidly disappears.
19. Sodium. — Like potassium, this alkali metal is detected by the color which its salts give to the flame.
If a sodium salt be held on the platinum wire in the flame, it imparts an intense yellow color.
The extreme delicacy of this reaction has been mentioned elsewhere. The value
36 BLOWPIPE ANALYSIS
of this test is really lessened by its great delicacy, for it is possible to detect minute quantities of sodium in almost all sub- stances, although it may not be in chemi- cal combination. As an example, draw the platinum wire between the fingers, and then place in flame, and note presence of sodium.
20. Lithium, Li20. — In the Bunsen flame on the platinum wire it imparts a carmine- red tinge.
Hydrochloric acid on the sample aug- ments the coloration.
THE ALKALINE EARTHS
21. Barium, BaO. — In the Bunsen flame on the platinum wire it imparts an apple- green coloration. This reaction is intensi- fied by moistening the sample with hydro- chloric acid.
GENERAL REACTIONS 37
22. Calcium, CaO. — In the Bunsen flame on the platinum wire it imparts an orange- red color, which appears gray when seen through blue glass.
Hydrochloric acid on the sample makes the color more intense.
23. Strontium, SrO. — In the Bunsen flame on the platinum wire it imparts an intensely red color, which is increased by converting the substance into the chloride.
THE ACID ELEMENTS
24. Borates. — If the substance be finely powdered, moistened with glycerine, and then placed on a platinum wire in the Bunsen flame, it imparts a brilliant green color.
If turmeric paper be dipped into a solu- tion of a borate, and then be dried at 1 00° C., it is turned to a peculiar red
38 BLOWPIPE ANALYSIS
color. These two reactions are extremely delicate.
25. Bromides. — Bromides treated with microcosmic salt and oxide of copper on platinum wire impart to the flame a greenish- blue color, the edges being decidedly green.
26. Chlorides. — Chlorides are treated in the same way as bromides. The color imparted to the flame is azure-blue.
To discriminate between bromides and chlorides more clearly, the substance is mixed with anhydrous potassium bisulphate and fused in an ignition tube.
Bromine and sulphur dioxide are evolved (if the substance be a bromide), the tube being filled with a yellow gas possessing the characteristic odor of bromine.
27. Fluorides. — A small portion of the substance in a finely powdered condition is
GENERAL REACTIONS 39
placed in one of the ignition tubes, a strip of moist Brazil-wood paper is introduced into the open end, and heat is applied. Hydrofluoric acid is evolved, and the red color of the paper is changed into a straw- yellow.
Mica, containing only 0.75% of fluorine, shows the reaction clearly.
28. Iodides. — Iodides are treated, as the bromides and chlorides, in a bead of micro- cosmic salt with oxide of copper. The flame is colored green.
Fused with potassium bisulphate in an ignition tube the violet vapors of iodine are evolved, and thus iodides may be dis- tinguished from chlorides and bromides.
29. Nitrates. — If a nitrate be heated upon charcoal before the Bp., violent defla- gration occurs. If the substance contain-
40 BLOWPIPE ANALYSIS
ing the nitric acid be mixed with a very small quantity of finely powdered potas- sium cyanide, the deflagration is accom- panied with ignition and detonation.
If the substance be mixed in a dry condition with dry potassium bisulphate, and is then heated in an ignition tube, red-brown nitrous fumes are evolved. This reaction takes place if there is but a small quantity of nitrate present.
30. Phosphates. — Phosphates impart to the flame a bluish green color. The color is made more intense by moistening the substance with sulphuric acid, and then taking the paste so formed on the plati- num wire and placing it in the Bunsen flame.
31. Silicates. — Silicates, when treated with microcosmic salt on a platinum wire,
GENERAL REACTIONS 41
suffer decomposition; the bases unite with the phosphoric acid to form a transparent glass in which the silica may be seen float- ing as a cloudy mass.
The bead must only be examined for silica while hot, since on cooling it becomes opaque.
32. Sulphides. — Many sulphides, when heated in an ignition tube, volatilize and give a sublimate of sulphur in combina- tion with the metallic portion of the sub- stance.
A very delicate test for sulphur in what- ever combination it may be found in a sub- stance, and which may be performed with great ease, is to mix the finely powdered assay with four parts, Na2CO3, and fuse in an ignition tube. When thoroughly fused the tube is broken, and the fused mass is placed on a bright silver coin, and a drop
42 BLOWPIPE ANALYSIS
of water is added. If the substance con- tains sulphur, a black spot will be observed on the coin where the fused mass was placed.
Before going on to the next chapter, the student should assure himself of his famil- iarity with the reactions just given, and he should practise with various substances, the nature of which is unknown to him.
CHAPTER IV
BEHAVIOR OF SOME OF THE PRINCIPAL ORES BEFORE THE BLOWPIPE
FOR the sake of practice, and as a fitting introduction to " Determinative Mineralogy," this chapter is appended. It is not intended to give a detailed account of the minerals, but rather to set before the student the most marked characters, such as hardness, specific gravity, color, lustre, etc.
To determine the hardness of a mineral, we try to scratch it with the minerals forming an arbitrary "scale of hardness," proceeding successively from the softest to the hardest. When we say that a certain mineral has hardness = 4, we mean that the mineral is scratched by 4 on the scale, and
43
44 BLOWPIPE ANALYSIS
that 4 on the scale is scratched by the mineral. The scale of hardness chiefly in use is the Mohs-Breithaupt scale, which is as follows: —
1. Talc, common laminated light green variety.
2. Gypsum, crystallized.
3. Calcareous spar, transparent variety.
4. Fluor spar, crystalline.
5. Apatite, transparent.
6. Orthoclase, white cleavable variety.
7. Quartz, transparent.
8. Topaz, transparent.
9. Sapphire, cleavable variety. 10. Diamond.
It seldom happens in determining the hardness of a mineral that its hardness ex- actly conforms to that of some one member of the scale. In such cases we generally estimate the hardness. For example, sup-
PRINCIPAL ORES BEFORE THE BLOWPIPE 45
pose a mineral was harder than 4, but softer than 5, and that it was nearer 5 than 4, then we would call its hardness 4^.
In order to preserve the scale some operators use a three-cornered file, first cutting the mineral and then the scale until a number is found, which is abraded to about the same depth as the mineral under examination.
Since a set of minerals forming a scale of hardness is not always at hand, the following scale given by Chapman is appended : —
1. Yields easily to the nail.
2. Yields with difficulty to the nail or just receives an impression from it. Does not scratch a copper coin.
3. Scratches a copper coin but is also scratched by it, being of about the same degree of hardness.
46 BLOWPIPE ANALYSIS
4. Not scratched by a copper coin. Does not scratch glass.
5. Scratches glass with difficulty, leaving its powder on it. Yields readily to the knife.
6. Scratches glass easily. Yields with difficulty to the knife.
7. Does not yield to the knife. Yields to the edge of a file, though with difficulty.
8. 9, 10. Harder than flint.
Specific gravity cannot well be deter- mined without the aid of a balance, and hence its value here is not great.
As in the preceding chapter, alphabetic arrangement will be employed.
ORES OF ANTIMONY
Stibnite, Sb2S3, Sb.;i, S.29. — *H = 2, 0 = 4.52—4.62. Of lead-gray color and metallic lustre. Consists of a large number
* H = Hardness, G = Specific Gravity.
PRINCIPAL ORES BEFORE THE BLOWPIPE 47
of needle-shaped crystals. Brittle. Fuses in candle flame. In an ignition tube yields a sublimate of sulphur. On Ch. before the Bp. it is volatilized, giving antimony coating and tinges the flame pale blue.
ORES OF ARSENIC
Native Arsenic, As. — This contains traces of Sb, Ag, Fe, Co, and Ni.
H = 3-5> 0 = 5.7-5.8. Dark gray in color. Fracture tin-white, tarnishing rap- idly. Volatilizes before the Bp. on Ch. without melting, giving white coating of arsenious acid and characteristic garlic odor. In ignition tube it sublimes, giving arsenical ring.
Realgar, AsS, As . 70, S . 30. — H = 1.5 — 2, 0 = 3.56. Bright red to orange-red color and resinous lustre. In an ignition tube it fuses and finally sublimes. The sub-
48 BLOWPIPE ANALYSIS
limate when cool is red and transparent. Fuses readily before the Bp. on Ch. and burns with - pale yellowish flame, emitting gray-white fumes having garlic odor.
Orpiment, As2S3, As . 61, S . 39. — H = 1.5 -2.0, 0=3.4-3.5.
Lemon-yellow in color and resinous or pearly lustre. Sectile. Before the Bp. on Ch. behaves like realgar, but in an ignition tube it gives a dark yellow sublimate which is transparent.
ORES OF BISMUTH
Native Bismuth, Bi. — This contains traces of As, Te, and S.
H = 2.0 - 2.5, G = 9.7 - 9.83. Color, silver- white, slightly tinged with red. Metallic lustre. Brittle when cold, but may be lami- nated when hot. Before the Bp. on Ch. behaves like pure Bi.
PRINCIPAL ORES BEFORE THE BLOWPIPE 49
Bismuthite, Bi2O3 . 90, CO2 . 7, H2O . 3, — H = 4.0 -4.5, 0 = 6.9-7.8.
Usually of a white or light greenish color and vitreous lustre, in acicular crystalliza- tions. In an ignition tube decrepitates, yielding water and turning gray. Before the Bp. on Ch. it fuses easily and is reduced to metallic globule, coating the Ch. with Bi2O3. With Na2CO3 it occasionally gives the sulphur reaction.
ORES OF CHROMIUM
Chromic Iron Ore, FeO.32, Cr2O8.68. — A12O3, Fe2O3, MnO, and MgO are commonly present. H = 5.5, 0 = 4.32-4.57. Occurs usually massive. Color, iron-black to brown- ish black. In many varieties strongly mag- netic. Lustre, shining and somewhat me- tallic. Heated in an ignition tube, remains unchanged. Infusible before the Bp. on Ch.
50 BLOWPIPE ANALYSIS
Before the Bp. on Ch. with Na2CO3 and KCN yields metallic iron. In borax bead it slowly dissolves to a clear transparent glass, which is a beautiful green when cool.
ORES OF COBALT
Smaltite, Co(Fe, Ni) As2, Co . 28, As . 72. — H = 5.5, G = 6.37 - 7.30. Color, tin-white or steel-gray. Lustre, metallic. When heated to redness in an ignition tube it yields a sublimate of metallic arsenic. Before the Bp. on Ch. it fuses readily, with emis- sion of arsenical fumes, to a grayish black magnetic globule. This globule may be examined for iron, cobalt, and nickel with the borax bead.
Cobaltite, CoS2 + Co As2, Co. 36, As. 45, 8.19. — H = 5.5, 0 = 6.0-6.3. Color, silver- white tinged with red. Metallic lustre. Before the Bp. on Ch. fuses easily, with
PRINCIPAL ORES BEFORE THE BLOWPIPE 5 1
emission of copious arsenical fumes, to a gray magnetic globule. Remains unchanged in the ignition tube.
Linnaeite, (Co, Ni)3S4, (Co, Ni)s8, 8.42.— H = 5«5, 0 = 4.8-5.0. Color, bright steel- gray, sometimes reddish. Lustre, metallic. Crystallizes in the regular octahedron. Before the Bp. on Ch. fuses to a metallic globule which is attracted by the magnet. With borax bead gives reaction for cobalt.
Erythrite, Co3O8As2 + 8 H2O, CoO.37.6, H2O.24.o.—
H= 1.5 -2.0, 0=2.95.
Color, crimson to peach-red. When crys- tallized, of pearly lustre, but frequently dull and earthy. Heated in ignition tube gives off water, and color changes to blue or green. Before the Bp. on Ch. in R. F. it
52 BLOWPIPE ANALYSIS
emits arsenical fumes and melts to a dark gray globule which with the borax bead reacts for cobalt.
ORES OF COPPER Native Copper, Cu. —
H = 2.5-3, 0 = 8.5-8.9.
Color, copper-red. Lustre, metallic. Oc- curs usually massive and very arborescent. Before the Bp. on Ch. it fuses, and if the heat is sufficiently high it assumes a bright bluish-green surface ; on cooling it is covered with a coat of black oxide. In the borax bead it reacts for copper.
Chalcopyrite, CuFeS2, Cu . 35, Fe . 30, 8.35.— H = 3.5 -4, 0 = 4.1-4.3. Color, brass-yellow, often golden-yellow. Lustre, metallic. Occurs crystallized, but is gener- ally found massive. Is easily scratched
PRINCIPAL ORES BEFORE THE BLOWPIPE 53
with a knife. Heated in an ignition tube decrepitates, and occasionally yields a faint sublimate of sulphur. Before the Bp. on Ch. it blackens, but becomes red again on cooling. Before the Bp. on Ch. with Na2CO3 and KCN it is reduced, and the metals are obtained in separate masses. It reacts with the borax bead for copper and iron.
Copper Glance, Cu2S, Cu .80, S . 20. — H = 2.5 - 3.0, G = 5.5 - 5.8. Color, dark blue to steel-gray. Occurs in compact masses, often very shining. Before the Bp. on Ch. fuses to a globule which boils and emits glowing drops. Sulphur dioxide escapes abundantly, and the outer flame is colored blue. Before the Bp. on Ch. with Na2CO3 yielding a metallic globule.
Tetrahedrite, 4 CuS + Sb2S3. — Frequently contains silver, iron, mercury, and zinc.
54 BLOWPIPE ANALYSIS
H = 3.0 -4.0, 0 = 4.5-5. Color, steel-gray to iron-black. Heated in an ignition tube fuses and gives a sublimate of antimonious oxide. When mercury is present this con- denses in the upper part of the tube, form- ing the characteristic mirror. Before the Bp. on Ch. it fuses readily to a metallic globule, emitting dense white fumes ; zinc and antimony coatings are deposited on the Ch. After long ignition before the Bp., if the mineral is finely powdered and mixed with Na2CO3 and KCN, the ore is reduced to the metal.
Cuprite, Cu2O, Cu . 89, 0 . 1 1. — H = 3.5 -4.0, 0 = 5.5-6.15.
Color, intense crimson-red. Before the Bp. on Ch. blackens and fuses quietly, and finally yields a metallic globule of copper. Before the Bp. on Ch. with Na2CO3 and KCN it is easily reduced.
PRINCIPAL ORES BEFORE THE BLOWPIPE 55
Malachite, 2 CuO + CO2+ H2O, CuO . 72, CO2.20, H2O.8.—
H = 3.5 -4.0, 0=3.90-4.03.
Color, bright green. Occurs generally in mammillated concretions. Lustre, shining and fracture, silky. Heated in an ignition tube yields water and blackens. Before the Bp. on Ch. it fuses to a metallic globule. Before the Bp. on Ch. with Na2CO3 and KCN it is easily reduced. With borax bead gives characteristic coloration.
Azurite, 3 CuO + 2 CO2+ H2O, CuO . 69, C02.26, H20.5.—
H = 3.5 -4.0, 0=3.77-3.83.
Color, azure-blue. Occurs usually in crys- tallized or globular masses. Lustre, earthy or vitreous. Before the Bp. and with other reagents behaves like malachite.
56 BLOWPIPE ANALYSIS
Chrysocolla CuO + SiO2 + 2 H2O, CuO.45.3, H2O.20.5. — H = 2.0- 3.0, G=2. Color, bluish-green, closely resembling mala- chite. Occurs usually as an incrustation, its surface being very smooth, like enamel. In an ignition tube it blackens and yields water. Before the Bp. on Ch. in O. F. it blackens, coloring the flame bright green; in the R. F. it turns red. Before the Bp. on Ch. with Na-jCO3 yields metallic copper. In borax bead it reacts for copper.
Atacamite, CuCl2 + 3 CuO2H2 - Cl . 16.6, 0 . 20.3, Cu . 50. i , H2O . 1 3.0. —
H = 3.0 -3.5, G= 3.75 -3.77.
Color, green to blackish green. Lustre, adamantine to vitreous. In an ignition tube yields water. Before the Bp. on Ch. colors flame blue. Before the Bp. on Ch. with Na2CO3 and KCN is reduced to the metal. In borax bead it reacts for copper.
PRINCIPAL ORES BEFORE THE BLOWPIPE S7
ORES OF IRON
Limonite, 2 Fe2O3 + 3 H2O, Fe2O8 . 86, H2O . 14. — H = 5.0-5.5, G = 3.6 - 4.0. Color, brown to ochre-yellow. Earthy or semi-metallic in appearance. In an igni- tion tube yields water. Before the Bp. on Ch. infusible. In borax bead reacts for iron.
Hematite, Fe,O3, Fe . 70, 0 . 30. — H = 5-5 -6-5, 0 = 4.9-5.3.
Color, dark steel-gray to iron-black. Lustre, metallic. When pulverized yields a red powder. Before the Bp. on Ch. infusible. After long roasting becomes magnetic. In borax bead gives usual indications of iron.
Magnetite, Fe3O4, FeO .31, Fe2O3 . 69. — H = 5-5 -6.5, 0=5.17-5.18.
58 BLOWPIPE ANALYSIS
Color, iron-black. Lustre, shining and me- tallic. Pulverized, its powder is black. It is strongly magnetic. Fuses with difficulty before the Bp. on Ch. In borax bead reacts for iron.
Pyrites, FeS2, Fe . 47, S . 53.—
H = 6.0 - 6.5, G = 4.95 - 5.20. Color, brass-yellow. Lustre, metallic. Oc- curs commonly in cubes. It often con- tains small quantities of Au, Ag, Cu, As, Co, and Mn. Heated in an ignition tube gives a sublimate of sulphur, the residue becoming magnetic. Before the Bp. on Ch. in O. F. sulphur is burned off and the red oxide remains. This residue may then be examined for iron, etc.
Marcasite (White Iron Pyrites). — Having the same general composition as pyrite, but much lighter in color. Crystals, prismatic. Before the Bp. on Ch. behaves like pyrite.
PRINCIPAL ORES BEFORE THE BLOWPIPE 59
Pyrrhotite, Fe7S8, Fe.6o.5, 8.39.5.— H = 3.5 -4.5, 0 = 4.58-4.64.
Color, bronze-yellow. Closely resembles pyrite, but may be distinguished from it by being feebly magnetic. Heated in an ignition tube yields no sublimate. Before the Bp. on Ch. fuses to a magnetic globule, which exhibits a yellowish crystalline struc- ture when fractured.
Mispickel, FeAsS, Fe.34, As. 46, 8.20. — H = 5.5~6.o, G = 6.0 -6.2. Color, silver- white. Lustre, metallic; very brittle. Often associated with it we find small quantities of Co, Ag, and Au. Heated in an igni- tion tube it first yields a red sublimate of sulphide of arsenic, and then afterward a crystalline sublimate of metallic arsenic. Before the Bp. on Ch. emits dense fumes of arsenic and deposits a coating on the
60 BLOWPIPE ANALYSIS
coal; it then fuses to a globule which behaves like pyrrhotite.
Siderite, FeCO3, FeO.62, CO2.38.— H = 3.5 -4.5, 0=3.7-3.9. Color, grayish yellow to reddish brown. Lustre, pearly. Crystallizes in rhombohedrons with curved faces ; these crystals are distinctly cleavable and massive. Heated in an ignition tube it decrepitates with evolution of carbon dioxide. Before the Bp. on Ch. infusible. Before the Bp. on Ch. with Na2CO3 it fuses to a magnetic mass. With borax bead it re- acts for iron and sometimes for manganese.
ORES OF LEAD Galena, PbS, Pb . 87, S . 1 3. — H = 2.5, 0=7.4-7.6.
Color, bluish gray, slowly tarnishing. Lus- tre, metallic. Crystals in the form of cubes.
PRINCIPAL ORES BEFORE THE BLOWPIPE 6 1
Heated in an ignition tube it sometimes decrepitates and yields a sublimate of sul- phur. Before the Bp. on Ch. easily reduced to the metallic state, the Ch. becoming coated with sulphate and oxide of lead. The metallic globule usually contains a little silver. To separate this, the process known as "cupellation" is employed. A hole is bored into the Ch. about i cm. in diame- ter and about 6 mm. deep. Into this hole is placed a stiff paste made by mixing finely pulverized bone-ash with a little soda and water. This paste is pressed in hard, and then the surface is smoothed off, and the centre is slightly depressed with the rounded end of a glass rod. The charcoal so pre- pared is set in a warm place to allow the paste to dry. When the paste is quite dry the small globule of lead is placed in the depression in the centre of the bone- ash "cupel," and is there exposed to the
62 BLOWPIPE ANALYSIS
O. F. from the Bp. The lead is oxidized and is absorbed by the bone-ash, while any silver present will remain in the central depression as a bright shining bead.
Cerusite, PbCO3, PbO . 84, CO2.i6.— H = 3.0 -3.5, 0 = 6.46-6.57. Color, white, gray, or yellow. Lustre, adamantine. Crys- tallizes in prismatic needles When heated in an ignition tube carbon dioxide is evolved and the residue turns yellow. Before the Bp. on Ch. readily reduced to metallic lead.
Anglesite, PbSO4, PbO . 74, SO3.26.— H = 2.0—3.0, 0 = 6.12 — 6.39. Color, yel- low, gray, and brown. Lustre, adamantine, resinous. Heated in an ignition tube decrepitates, and sometimes yields a little water. Before the Bp. on Ch. fuses to a clear bead, which on cooling becomes
PRINCIPAL ORES BEFORE THE BLOWPIPE 63
opaque. Before the Bp. on Ch. with Na2CO3 is reduced to the metal giving a yellow coating. The Na^Og absorbed by the coal reacts for S.
ORES OF MANGANESE
Pyrolusite, MnO2, Mn . 63.2, O . 36.8. — H = 2.0—2.5, 0 = 4.82. Color, iron-black to steel-gray. Lustre, non-metallic. Heated in an ignition tube yields generally a little water, and if the temperature be high enough, oxygen is evolved. Before the Bp. on Ch. infusible. In borax bead gives characteristic color.
Psilomelane, Mn2O8 + H2O. —
H = 5.5 -6.0, 0=3.7-4.7.
Color, iron-black to steel-gray. Generally resembles pyrolusite, but is distinguished from it by its superior hardness. It fre-
64 BLOWPIPE ANALYSIS
quently contains BaO and Li2O. It behaves before the Bp. like pyrolusite.
Wad (Bog Manganese). — This mineral is essentially MnO2, MnO, and H2O, with small quantities of Fe2O3, A12O3, BaO, SiO2, etc., associated with it.
H = 0.5 -6.0, 0 = 3.0-4.2. Color, dull black. Heated in an ignition tube yields water in abundance, otherwise it behaves like pyrolusite.
ORES OF MERCURY
Native Mercury, Hg. — G = 13.5 — 13.6. Color, silver-white. Is liquid at all ordi- nary temperatures. Heated in an ignition tube is volatilized, the vapors condensing in the upper end of tube to small metallic globules of Hg. Before the Bp. on Ch. it is volatilized. Frequently contains Ag.
PRINCIPAL ORES BEFORE THE BLOWPIPE 65
Cinnabar, HgS2, Hg.86, S. 14. — H = 2.0 -2.5, G = 8.0 -8.2.
Color, scarlet-red to brick-red. Lustre, non- metallic. When pulverized yields a powder of vermilion-red color. Heated in an ig- nition tube it volatilizes, yielding a black sublimate, which by friction becomes red. Before the Bp. on Ch. it is wholly vola- tilized. Heated in an ignition tube with Na2CO3 metallic mercury sublimes, con- densing in the upper portion of the tube in minute globules.
ORES OF NICKEL
Millerite, NiS, Ni.644, $.35.6.— H = 3.0 -3.5, 0=5.2-5.6.
Color, brass-yellow. Brittle. Before the Bp. on Ch. it fuses to a magnetic, metallic globule. The roasted mineral gives in the borax bead the color reaction characteristic
66 BLOWPIPE ANALYSIS
of nickel, and sometimes that of cobalt, which is often associated with it.
Niccolite, NiAs, Ni . 44, As . 56. — H = 5.0 -5.5, G= 7.35 -7.67.
Color, pale copper-red. Lustre, metallic. Very brittle. Heated in an ignition tube yields a copious sublimate of arsenious oxide, the residue falling to a greenish powder. Before the Bp. on Ch. fuses to a white brittle globule emitting arsenical fumes. In borax bead gives color character- istic of nickel. Frequently in this mineral a portion of the arsenic is replaced by antimony.
ORES OF SILVER Native Silver, Ag. —
H = 2.5 — 3.0, G=IO.I — n.o. Color, silver-white. Lustre, metallic. Duc- tile and malleable. Usually occurs asso-
PRINCIPAL ORES BEFORE THE BLOWPIPE 6/
ciated with Au, As, Sb, Cu, Fe, etc. Before the Bp. on Ch. easily fuses to a globule which is surrounded with a dark red coating on the coal.
^
Argentite, Ag.2S, Ag.S/.i, S. 12.9. — H = 2.0 — 2.5, 0=7.20-7.36.
Color, blackish lead-gray. Lustre, metallic. Very sectile. Before the Bp. on Ch. in O. F. intumesces with evolution of sulphur dioxide, finally yielding a metallic globule of Ag.
Pyrargyrite, Ag3SbS3, Ag.59.8, Sb.22.5, 8.17.7.— H = 2.5, 0=5.77-5.86. Color, black to dark cochineal-red. Lustre, metal- lic, adamantine. In an ignition tube it yields on continued heating a sublimate of antimony sulphide. Before the Bp. on Ch. it gives a coating of antimony trioxide.
68 BLOWPIPE ANALYSIS
Before the Bp. on Ch. with Na2CO3 is reduced to metallic silver.
Proustite, Ag3S3As, Ag.65.5, As. 15.1, S. 194.— H = 2.0 -2.5, 0=5.57-5.64. Color, light red. Lustre, splendent, adaman- tine. Before the Bp. on Ch. it behaves like pyrargyrite, save that it gives off arsenical fumes instead of antimonious oxide.
Stephanite, Ag5S4Sb, Ag.68.5, Sb.is.3, S . 16.2. — H = 2.0 — 2.5, G = 6.2 — 6.3. Color, iron-black to blackish gray. Lustre, me- tallic. Very brittle and fragile. In an ig- nition tube it decrepitates, fuses, and finally yields a slight sublimate of antimony tri- sulphide. Before the Bp. on Ch. gives a coating of antimonious oxide. Before the Bp. on Ch. with Na2CO3 a globule of metallic silver is obtained. The mineral frequently contains copper and iron.
PRINCIPAL ORES BEFORE THE BLOWPIPE 69
Kerargyrite, AgCl, Ag.75«3, 0.24.7.— H =1.0—1.5, 0=5.52. Color, white, gray, yellowish, greenish to blue. Lustre, resin- ous, adamantine. Soft like wax. Fuses easily in a candle-flame. Before the Bp. on Ch. it is readily reduced to metallic silver.
ORES OF TIN
Cassiterite, SnO2, Sn.79, O.2i. — H = 6.0 -7.0, 0 = 6.8-7.0.
Color, brown, black. Lustre, adamantine, brilliant. Occurs crystallized in square prisms. Reentrant angles characteristic. Before the Bp. on Ch. with Na2CO3 and KCN reduced to a metallic globule of tin. In the borax bead gives characteristic re- action.
Stannite, 2 Cu2S . SnS2 + 2 (FeS . ZnS) Sn . S2. — H = 4.0, G = 4.3 — 4.5. Color,
70 BLOWPIPE ANALYSIS
steel-gray to iron-black. Lustre, metallic. Occurs usually massive and disseminated. Heated in an ignition tube it yields sul- phur dioxide. Before the Bp. on Ch. it emits sulphur dioxide and becomes cov- ered with oxide of tin. Before the Bp. on Ch. with Na2CO3 and KCN it gives an impure globule of copper. A very difficult mineral to determine.
ORES OF ZINC
Calamine, H2Zn2O5Si, SiO2.25.o, ZnO. 67.5, H2O.7.5.— H = 4.5 -5.0, 0=34-3.5. Color, white, gray, bluish, or brown. Lustre, vitreous. Brittle. In an ignition tube yields water when heated and becomes milky white. Before the Bp. on Ch. prac- tically infusible. With Co(NO3)2 it assumes a green color which passes into a fine blue when the heat is increased.
PRINCIPAL ORES BEFORE THE BLOWPIPE 71
Smithsonite,
Zn . CO3, ZnO . 64.8, CO2 . 35.2. —
H = 5, 0 = 4.30-445. Color, gray, yellow, brown, and green. Lustre, vitreous, pearly. Heated in an ignition tube CO2 is evolved, residue appearing white. It often contains impurities of Cd, Pb, Fe, Mn, Ca, and Mg. When these are present the residue in the ignition tube becomes dark on cooling. Before the Bp. on Ch. with Na2CO3 and exposed to the R. F. it is decomposed. It gives the characteristic reaction for zinc with Co(NO3)2.
Zincite, ZnO, Zn . 80.3, 0 . 19.7. — H = 4.0 -4.5, 0 = 5.43-5.70.
Color, blood-red. Lustre, brilliant, sub- adamantine. Before the Bp. on Ch. infusible. Before the Bp. on Ch. with Na2CO3 gives coating of zinc oxide. Oives characteristic
72 BLOWPIPE ANALYSIS
reaction with Co(NO3)2. It frequently con- tains a small quantity of Mn2O3, which may be detected in the borax bead.
Sphalerite, ZnS, Zn . 67, S . 33. — H = 3-5-4-0, 0=3.9-4.1.
Color, yellow to black. Lustre, resinous, brill- iant, and sometimes submetallic. Heated in an ignition tube sometimes decrepitates. Before the Bp. on Ch. infusible. Before the Bp. on Ch. with Na2CO3 easily reduced. With Co(NO8)2 gives the characteristic re- action. It frequently contains small quan- tities of Cd, Hg, Sn, Pb, Au, Ag, etc.
PRINCIPAL ORES BEFORE THE BLOWPIPE 73
TABLE OF COLORS OF COATINGS ON CHARCOAL
|
ELEMENT |
COLOR HOT |
COLOR COLD |
|
Antimony Arsenic Bismuth Cadmium |
(Rather volatile) (Very volatile) Orange-Yellow Brownish Yellow |
White White Lemon-Yellow Reddish Brown |
|
Lead Silver |
Lemon- Yellow (volatile) Dark Red |
Lemon-Yellow Dark Red |
|
Tin |
Faint Yellow |
White |
|
Zinc |
Yellow |
White |
II
TABLE OF FLAME COLORATIONS
|
RED |
YELLOW |
GREEN |
|
Calcium |
Sodium |
Barium |
|
Lithium |
Boron |
|
|
Strontium |
Iodine |
|
|
BLUISH GREEN |
BLUE |
VIOLET |
|
Bromine |
Chlorine |
Potassium |
|
Copper |
||
|
Phosphorus |
74
BLOWPIPE ANALYSIS
III
TABLE OF COLORS OF BORAX BEADS IN OXIDIZING FLAME
|
ELEMENT |
COLOR HOT |
COLOR COLD |
|
Aluminum |
Colorless to Cloudy |
Colorless to Cloudy |
|
Antimony |
Yellowish |
Colorless |
|
Barium |
Colorless to Opaque |
Colorless to Opaque |
|
Bismuth |
Yellow |
Colorless |
|
Cadmium |
Yellow |
Colorless to White |
|
Calcium |
Colorless |
Colorless |
|
Chromium |
Reddish Yellow |
Yellowish Green |
|
Cobalt |
Blue |
Blue |
|
Copper |
Green |
Greenish Blue |
|
Iron |
Orange |
Yellow |
|
Lead |
Yellow |
Colorless |
|
Magnesium |
Colorless |
Colorless |
|
Manganese |
Violet |
Reddish Violet |
|
Nickel |
Violet |
Reddish Brown |
|
Silver |
Colorless |
Milk-White |
|
Strontium |
Colorless to Opaque |
Colorless to Opaque |
|
Tin |
Colorless |
Colorless |
|
Zinc |
Yellowish |
Colorless |
PRINCIPAL ORES BEFORE THE BLOWPIPE ?$
IV
TABLE OF COLORS OF BORAX BEADS IN REDUCING FLAME
|
ELEMENT |
COLOR HOT |
COLOR COLD |
|
Aluminum |
Colorless |
Colorless |
|
Antimony |
Colorless |
Cloudy |
|
Barium |
Colorless |
Colorless |
|
Bismuth |
Colorless |
Gray — Cloudy |
|
Cadmium |
Colorless |
Gray — Cloudy |
|
Calcium |
Colorless |
Colorless |
|
Chromium |
Green |
Green |
|
Cobalt |
Blue |
Blue |
|
Copper |
Colorless |
Red |
|
Iron |
Yellowish Green |
Yellowish Green |
|
Lead |
Colorless |
Gray |
|
Magnesium |
Colorless |
Colorless |
|
Manganese |
Colorless |
Pink |
|
Nickel |
Colorless |
Gray — Cloudy |
|
Silver |
Colorless |
Gray |
|
Strontium |
Colorless |
Colorless |
|
Tin |
Colorless |
Colorless |
|
Zinc |
Colorless |
Gray |
BLOWPIPE ANALYSIS
TABLE OF COLORS OF MICROCOSMIC SALT BEADS IN OXIDIZING FLAME
|
ELEMENT |
COLOR HOT |
COLOR COLD |
|
Aluminum |
Colorless |
Colorless |
|
Antimony |
Yellowish |
Colorless |
|
Barium |
Colorless to Opaque |
Colorless to Opaque |
|
Bismuth |
Yellow |
Colorless |
|
Cadmium |
Yellowish |
Colorless |
|
Calcium |
Colorless |
Colorless to Opaque |
|
Chromium |
Reddish |
Green |
|
Cobalt |
Blue |
Blue |
|
Copper |
Green |
Greenish Blue |
|
Iron |
Red |
Brownish Red |
|
Lead |
Yellowish |
Colorless |
|
Magnesium |
Colorless |
Colorless |
|
Manganese |
Brownish Violet |
Reddish Violet |
|
Nickel |
Reddish |
Yellow |
|
Silver |
Yellowish |
Yellowish |
|
Strontium |
Colorless |
Colorless |
|
Tin |
Colorless |
Colorless |
|
Zinc |
Yellowish |
Colorless |
PRINCIPAL ORES BEFORE THE BLOWPIPE 77
VI
TABLE OF COLORS OF MICROCOSMIC SALT BEADS IN REDUCING FLAME
|
ELEMENT |
COLOR HOT |
COLOR COLD |
|
Aluminum |
Colorless |
Colorless |
|
Antimony |
Colorless |
Gray — Cloudy |
|
Barium |
Colorless |
Colorless |
|
Bismuth |
Colorless |
Gray — Cloudy |
|
Cadmium |
Colorless |
Gray — Cloudy |
|
Calcium |
Colorless |
Colorless |
|
Chromium |
Reddish |
Green |
|
Cobalt |
Blue |
Blue |
|
Copper |
Dark Green |
Brownish Red |
|
Iron |
Red |
Reddish |
|
Lead |
Colorless |
Gray — Opaque |
|
Magnesium |
Colorless |
Colorless |
|
Manganese |
Colorless |
Colorless |
|
Nickel |
Colorless |
Gray |
|
Silver |
Colorless |
Gray |
|
Strontium |
Colorless |
Colorless |
|
Tin |
Colorless |
Colorless |
|
Zinc |
Colorless |
Gray — Cloudy |
THE PRACTICAL METHODS
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