A study of the vitrification range and di-electric behavior of some Porcelains

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J

UNIVERSITY OF ILLINOIS BULLETIN

Vol. VII. MARCH 14, 1910. No. 28

[Entered February 14, 1902, at Urbana, Illinois, as second-class matter under
Act of Congress of July 16, 1894. ]

BULLETIN No. 13
DEPARTMENT OF CERAMICS

A. V. BLEININGER, Director

\ STUDY OF THE VITRIFICATION RANGE

AND DLELECTRIC BEHAVIOR OF

SOME PORCELAINS

BY

A. V. BLEININGER, Pittsburg, Pa,, and

R. T. STULL, Urbana, III.

1909-1910

PUBLISHED FORTNIGHTLY BY THE UNIVERSITY

[Reprinted from Transactions of American Ceramic Society, Vol. XII.
Paper read at Pittsburgh Meeting, February, 1910.]

A STUDY OF THE VITRIFICATION RANGE AND

DIELECTRIC BEHAVIOR OF SOME

PORCELAINS.

BY

A. V. Bleininger^ Pittsburg, Pa., and R. T. Stull,
Urbana, 111.

The object of this work, Avhich was begun in the sum-
mer of 1908, was to show by graphical means the propor-
tions of clay, feldspar and flint which produce vitrified
clay bodies at temperatures within the limits of American
practice. At the same time this opportunity was taken
to show, if possible, the relation between the composition
of the bodies and their electrical resistance. In order to
bring out the effect of introducing the various clays used
in the industries it was decided to cover the field outlined
by using Tennessee ball clay No. 3, North Carolina kaolin,
English China clay and Georgia kaolin. All of these
materials, as well as the feldspar and flint were obtained
from the Avorks of the Mayer Pottery Company, Beaver
Falls, Pa., through the kindness of Mr. Ernest Mayer and
Mr. Her ford Hope.

The materials were analyzed in tlie chemical depart-
ment of the University of Illinois. The results of the
analyses, as well as the empirical formuhTe of tliese compo-
nents are given in the following table:

Chemical Analysis of Materials.

N. C. Kaolin Eng. China Clay Georjia Kaolin.

Potash Spar.

BiO

I
..! 48.54%

45.74%o

47.06%

46.86%o

70.03%

Al,03 ...

..1 36.25%

40.18%

38.70%

38.67%

17.80%

Fe.O., ...

.07%

.57%

.40%

.57%

.21%

CaO ....

.32%

.30%

.58%

.55%

.98%,

MgO ....

..| .32%

.34%

.49%

.25%

.16%

K.O ....

.70%

1.19%

1.05%

.27%

8.71%

Na.,0 ....

.28%

.55%

.23%

.49%

1.61%

H„0 ....

..1 12.13%

1

14.30%c

12.22%

13.27%

.35%

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

Chemical Formulae.

.0209 K,0
.0127 Na.O
Tennessee Ball .0161 Cab

Clay .. .0225 MgO

.0722

' '■ .0321 K.O ^
.0225 Na„0
North Carolina .0136 Cab
Kaolin 0216 MgO

.0898

r0294"KTxr^
.0098 Na.,0

English China .0273 Cab

Clay .0323 MgO

1.0000 ALO..
.0118 Fe„0. 2.276 SiO.,

Mol. Wt. = 279.173

1.0000 ALO,
.0090 FGoO, 1.935 SiO..

Mol. Wt. = 261.898

1.0000 ALO-i
.0066 Fe.,b.. 2.067 SiO,

Mol. Wt. = 265.507

Georgia Kaolin.

.0076 K..0
.0208 Na„0
.0258 Cab
.0164 MgO

.0706

3.0000 Al.,0,
.0094 Fe.O.. 2.055 SiO,

Mol. Wt. = 275.816

Potash Spar . .

.5283 K.,0
.1480 Na.,0
.0998 Cab
.0228 MgO

.7989

1.0000 Al.,0..
.0075 Fe.,0' 6.655 SiO,

Mol. Wt. --569.832

The scheme of compounding' the bodies was simple.
Starting- with a mixture of 50% of clay and 50% of feld-
spar the latter was gradually replaced by flint down to a
content of 5% feldspar. The amount of clay was then
increased to 55% and again the feldspar replaced as be-
fore. This was continued until a clay content of 80% was
reached.

In table I the composition of the bodies and their for-
mulae are given.

Preparation of Specimens.

The clays were blunged and screened in the usual
manner, and from the prepared bodies two kinds of speci-
mens were made. For the purpose of obtaining measure-
ments of the porosity at different temperatures small

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.
TABLE I.

BATCH

FORMULA

No.

Ga.
Kaul.

Spar.

Flint

KoO 1 Na^O

CaO 1 MgO Al,03 FeoOj SiO-.

i

A 1

100
50
50

50
50
50
50
50
50
50
50
55
55
55
55
55
55
55
55
55
60
60
60
60
60
60
60
60
65
65
65
65
65
65
65
70
70
70
70
70
70
75
75
75
75
75
75

0
50
45
40
35
30
25
20
15
10

5
45
40
35
30
25
20
15
10

5
40
35
30
25
20
15
10

5
35
30
25
20
15
10

5
30
25
20
15
10

5
25
21
17
13

9

5

0

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

0

5

10

15

20

25

30

0

5

10

15

20

25

0

4

8

12

16

20

.0076

.0208

.0258
.0502
.0485
.0443
.0449
.0427
.0404
.0379
.0352
.0322
.0295
.0476
.0452
.0437
.0416
.0395
.0371
.0346
.0318
.0293
.0438
.0423
.0402
.0383
.0360
.0837
.0311
.0287
.0414
.0396
.0375
.0355
.0332
.0308
.0286
.0392
.0370
.0350
.0329
.0306
.0286
.0361
.0347
.0335
.0310
.0299
.0282

.0164
.0186
.0185
.0184
.0181
.0180
.0180
.0176
.0174
.0171
.0168
.0183
.0182
.0180
.0178
.0177
.0175
.0173
.0170
.0168
.0181
.0179
.0177
.0177
.0174
.0172
.0170
.0168
.0178
.0174
.0175
.0173
.0172
.0170
.0168
.0176
.0175
.0173
.0172
.0170
.0168
.0174
.0170
.0172
.0166
.0170
.0168

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

1

.0095
.0089
.0088
.0091
.0091

2.055

2

.1777
.1660
.1531
.1397
.1248
.1093
.0925
.0742
.0534
.0316
.1555
.1430
.1303
.1163
.1015
.0857
.0682
.0498
.0293
.1349
.1226
.1088
.0953
.0804
.0640
.0468
.0279
.1154
.1027
.0893
.0754
.0599
.0438
.0262
.0973
.0847
.0717
.0568
.0417
.0252
.0801
.0700
.0593
.0472
.0362
.0239

.0625
.0596
.0565
.0535
.0496
.0458
.0416
.0323
.0322
.0268
.0571
.0541
.0598
.0476
.0440
.0401
.0359
.0314
.0264
.0502
.0440
.0457
.0425
.0388
.0349
.0307
.0261
.0471
.0441
.0408
.0373
.0336
.0296
.0254
.0427
.0397
.0364
.0329
.0291
.0252
.0380
.0363
.0335
.0303
.0278
.0285

3.555

3

3.675

4

4.002

4.249

6

.009014.513

7

.009414.850

8

.0093 5.113

9

.0092 5.450

10

.0091|5.817

11

.00954.216

12

.009013.359

13

.0093 3.557

14

.0092 3.775

15

.00914.008

16

.0095 4.254

17

.0094 4.520

18

.0093 4.807

19

.0092 5.114

20

.0096 5.456

21

.0090|3.178

22

.0089|3.367

23

.008913.556

24

.0091
.0091
.0090
.0089
.0093
.0091
.0090
.0093

3.781

25

4.015

26

4.262

27

4.527

28

4.813

29

3.006

30

3.187

31

3.368

32

. 009213. 571

33

.0092 3.790

34

.00914.021

35

.0094

4.266

36

.0091
.0094
.0093
.0094
.0092
.0095
.0092
.0092
.0090
.0090
.0090
.0093

2.846

37

3.013

38

3.192

39

3.381

40

3.582

41

3.796

42

2.692

43

2.788

44

2.625

45

46

47

3.028
3.236

3.387

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

TABLE I — Continued.

BATCH

FORUMLA

No

Ga.

Kaol.

Spar

Flint

K,0

Na^O

CaO

MgO

AI2O3

Fe^Oa

SiOo

A 48

75

80
80
80
80
80
80
80

Tenn.
Ba'l.

100
50
50

50
50
50
50
50
50
50
50
55
55
55
55
55
55
55
55
55
60
60
60
60
60
60
60
60
65
65
65
65
65
65
65
70
70
70
70
70

1

20
17
14
11

8
5
2

0
50
45
40
35
30
25
20
15
10

5
45
40
35
30
25
20
15
10

5
40
35
30
25
20
15
10

5
35
30
25
20
15
10

5
30
25
20
15
10

24

0

3

6

9

12

15

18

0

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

0

5

10

15

20

25

30

0

5

10

15

20

.0109

.0640
.0563
.0483
.0401
.0314
.0228
.0140

.0209
.1876
.1764
.1636
.1502
.1359
.1206
.1041
.0857
.0661
.0442
.1663
.1542
.1416
.1276
.1133
.0980
.0806
.0599

.0218
.0346
.0328
.0308
.0291
.0270
.0250
.0225

.0127
.0573
.0543
.0509
.0472
.0436
.0395
.0350
.0302
.0250
.0192
.0515
.0483
.0449
.0401
.0374
.0332

.0282
.0339

.0328
.0318
.0304
.0293
.0281
.0268

.0161
.0438
.0415
.0393

. 0378

.0163
.0173

.0172
.0172
.0168
.0168
.0167
.0167

.0225
.0225
.0225
.0224
.0224

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

.0092
.0092

3.549

49

2.552

50

.009012.639

51

.0092
.0091
.0092

2 733

52

2.829

53

'). c»57

, 54

.0094 3.278

55

.0092 3 134

B 1

.0118 2.27fi

2

.0105
.0105
.0108
.0108
.0108
.0112

3.715

3

3.937

4

4.177

5

4.432

6

.0354 .0224
.0327 .0224
.0300 .0224

4.707

5 . 000

8

.0112i5.327

9

.0268
.0234
.0202
.0402
.0382
.0364
.0340
.0311
.0289

.0224
.0224
.0223
.0224
.0224
.0225
.0224
.0224
.0224
.0224
.0214
.0223
.0224
.0224
.0224
.0225
.0224
.0224
. 0223
.0223
.0224
.0224
.0224
.0224
.0224

.0112i5.677

10

.011216.058

11

.011716.471

12

.010513.528

13

.01093.738

14

.010813.951

15

.01084.195

16

.0112 4.455

17

.0112 4.735

18 •

.0287 .0260

.0112 5.027

19

.0227

.0218
.0200
.0368
.0351
.0329
.0305
.0280
.0253
.0223
.0197
.0340
.0319
.0297
.0272
.0247

.0107 5.111

20

. 04241. OlS.'j

.011615.700

21

.1459
.1339
.1207
.1070
.0924
.0763
.0509
.0407
.1271
.1145
.1016
.0877
.0726
.0568
.0393
.1088
.0964

.0463
.0435
.0400
.0359
.0320
.0279
.0232
.0183
.0411
.0378
.0343
.0306
.0266
.0224
.0178
.0363
.0329

.0109 3.354

22

.0109 3.550

23

24

25

26

27

28

29,

30

31

.0108 3.760
.0112 3.984
.011214.224
.0112 4.482
.0112 4.758
.011615.059
.010913.189
.010913.725
.OII2I3.494

32

.011213.781

33

.011214.001

34

.0220 .0224
.0194 .0224
.0310 .0224
.02821.0224
.0266 .0224
.0245 .0224
.0216 .0224

.011214.245

35

.011614.504

36

.011013.035

37

.011113.244

38

.0833 .0294
.0689 .0257
.0541 .0216

1 . 000

.011213.398

39

1.000
1.000

.011213.595

40

.011213.805

VITRIFICATION RANGE AND DI-ELECTRIC BKHAVIOR.

TABLE I— Continued.

i

BATCH

FORUMLA

., Tenn.
N°- Ball, j

Spu

Flint

K.O Na..O CaO MgO

AI2O.,

FeoOa

SiOo

B 41

70

75
75
75
75
75
75
75
SO
80
80
80
80
80
80

N. C.
Kail.
100

50
50
50
50
50
50
50
50
50
50
55
55
55
55
55
55
55
55
55
60
60
60
60
60
60
60
60
65
65
65
65
65

5

25

21

17

13

9

5

1

20

17

14

11

S

5

2

0
50
45
40
35
30
25
20
15
10

5
45
40
35
30
25
20
15
10

5
40
35
30
25
20
15
10

5
35
30
25
20
15

25 1

0

4 '

8
12
16
20
24

0

3

6

9
12
15
18

0

0

5
10
15
20
25
30
35
40
45

0

5
10
15
20
25
30
35
40

0

5
10
15
20
25
30
35

0

5
10
15
20

.0339 .0173i 0193|- >^'>.9.4.\

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1 . 000

0I15U 030

42

.0922 0.^171 (i'>S9

.0224J
.0223
.0224
.02231
.0223;
.0223:
.02221

0ll2i2 891

43

44

.0822
.0717

.0291 .0265
.0261 .0248

.01113.022
0111 3 159

45

.0607
.0488
.0368
.0241
.0765
.0689
.0611
.0530
.0446
.0359
.0238

.0321
.1884
.1774
.1654
.1530
.1392
.1248
.1093
.0921
.0739
.0535
.1678
.1207
.1444
.1313
.1177
.1033
.0872
.0703
.0517
.1483
.1372
.1245
.1117
.0980
.0830
.0673
.0500
.1303
.1153
.1065
.0935
.0794

.02341.0230
.02021.0212
.0170|.0191
.013'/|.0170

01133 305

46

.011213.457
.0115 3.619

47

48

.0115 3-787

49

.O277I.O252

09'2r

.0115
.0114
.0115
.0115

2.753

50

.0256 .0240J. 0224
. 02351. 0228i. 0225

2.846

51

2.942

52

.02161. 02131.022211. 000
.01931.0200 .0223 1.000
. 01691. 0j86 .0223 1.000
.0145|.0173 .0224il.000

3 . 041

53

.0116 3.151

54

.0118
.0117

.0090

.0086
.0085
.0088
.0087
.0087
.0085
.0089
.0088
.0087
.0090
.0086
.0089
.0088
.0087
.0090
.0090
.0089
.0089
.0090
.0087
.0086
.0085
.0088
.0087
.0086
.0085
.0088
.0087
.0086
.0089
.0089
.0087

3.251

55

3.456

G 1

.0225

.0136

.0216

1.000

1.935

2

.0621
.0593
.0563
.0531
.0496
.0460
.0420
.0378
.0331
.0280
.0567
.0539
.0508
.0476
.0441
.0400
.0364
.0321
.0274
.0520
.0493
.0461
.0432
.0394
.0356
.0316
.0273
.0471
.0446
.0414
.0381
.0346

.0409
.0352
.0364
.0349

.0219
.0219
.0218
.0218

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

3.420

3

3.623

4

3.842

5

4.073

6

.0324

.0218

4.323

7

.0298
.0270
.0239
.0206
.0175
.0374
.0354
.0335
.0312
.0287

.0217
.0217
.0217
.0216
.0215
.0218
.0218
.0217
.0217
.0216

4.591

8

4.880

9

5.192

10

5.532

11

5.898

12

3.224

13

3.417

14

3.616

15

3.832

16

4.061

17

.02611.0216

4.312

18

.0233
.0202
.0174
.0337
.0321

.0216
.0215
.0215
.0217
.0217

4.577

19

4.863

20

5.171

21

3.037

22

3.225

23

.02981.0216
.02751.0216
.0250L0216
.0223i.0215

3.404

24

3.609

25

3.823

26

4.053

27

28

.0195
.0168
.0310

.0215
.0215
.0216

4.299
4.559

29

2.867

30

.02891.0216
.02671.0216
.02441.0216

3.036

31

3.214

32

3.401

33

.0219

|.0215

13.601

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

TABLE 1 — Continued.

BATCH

FORUM LA

No.

N. C.
Kaol.

Spar

Flint

KjO

NaoO

CaO MgO

Al.,03 FeoOs

biOo

0 34

65

65

70
70
70
70
70
70
75
75
75
75
75
75
75
80
80
80
80
80
80
80

E"g.
Cliiim

100
50
50
50
50
50
50
50
50
50
50
55
55
55
55
55
55
55
55
55
60
60
60
60
60
60

10

5

30

25

20

15

10

5

25

21

17

13

9

5

1

20

17

14

11

8

5

2

0
50
45
40
35
30
25
20
15
10

5
45
40
35
30
25
20
15
10

5
40
35
30
25
20
15

25

30

0

5

10

15

20

25

0

4

8

12

16

20

24

0

3

6

9

12

15

18

0

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

1

.0647
.0486
.1145
.1019
.0899
.0763
.0624
.0474

.0309
.0268
.0431
.0401
.0370
.0337
.0302
.0264

.0192 .0214

1.000
1.000

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

!
.0086
.0089
.0088
.0090
.0089
.0089
.0088

3.815

35

.0167

.0214

4.045

36

.0247
.0257
.0235
.0211
.0186
.0163
.0254
.0235
.0219
.0201
.0182
.0163
.0142
.0226
.0215
.0203
.0188
.0175
.0162
.0149

.0273
.0504
.0487
.0468
.0332
.0431
.0409
.0385
.0360
.0330
.0304
.0475
.0458
.0443
.0423
.0402
.0380
.0356
.0330
.0306
.0446
.0431
.0405
.0382
.0371
.0349

.0218
.0215
.0215
.0215
.0214
.0214
.0216
.0214
.0215
.0214
.0215
.0214
.0212
.0217
.0218
.0218
.0216

2.680

37

2.892

38

3.067

39

3.243

40

3.428

41

.0090 3.632

42

.0979

.0391

.0090 2.231

43

.0885
.0788
.0686
.0576
.0464
.0347
.0835
.0763
.0691
.0616
.0538
.0459
.0379

.0294
.1880
.1770
.1648
.1480
.1382
.1236
.1079
.0904
.0718
.0513
.1675
.1558
.1437
.1304
.1168
.1020
.0857
.0686
.0495
.1475
.1360
.1235
.1104
.0965
.0812

.0369
.0342
.0317
.0288
.0261
.0233
.0355
.0337
.0318
.0302
.0281
.0261
.0239

.0098
.0536
.0505
.0472
.0436
.0398
.0358
.0313
.0266
.0214
.0157
.0480
.0447
.0413
.0377
.0338
.0297
.0253
.0204
.0153
.0425
.0393
.0359
.0322
.0283
.0242

.0090 2.681

44

.0090
.0090
.0090
.0090
.0090
.0089

2.802

45

2.932

46

2.066

47

3.206

48

3.353

49ft

2.451

50

.008712.504

51

.008812.588

52

.0086 2.678

53

.0216 1.000

.0087 2.764

54

.0217
.0217

.0323
.0293
.0296
.0298
.0300
.0303
.0306
.0309
.0312
.0315
.0320
.0297
.0299
.0302
.0303
.0306
.0314
.0317
.0316
.0320
.0300
.0303
.0313
.0308
.0310
.0305

1.000
1.000

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

.0089 2.863

55

.0090 2.959

D 1

.0066 2.067

2

.0069 3.525

3

.006713.734

4

.006913.957

Q

.0068

4.192

6

.0066
.0069
.0067
.0066
.0064

4.452

4.728

s

5.003

9

5.348

10

5.698

11

l.OOOl. 006616. 077

12

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

.007013.334

13

.007213.529

14

.0071
.0069
.0072
.0070

3 . 692

15

3.956

16

4.197

17

4.453

18

.0069 4.729

19

.0067 5.023

20

.00715.340

21

.007113.150

22

.007013.336

23

.0068
.0070
.0069
.0067

3.531

24

3.738

25

3.961

26

4.197

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

TABLE I— Continued.

j

BATCH

I

^ORUMLA

No. 1

ling.
China

Spar

Flint

K3O NaoO CaO

MgO

AI2O3

Fe^O^ SiOo

D 27

60

60
65
65
65
65
65
65
65
70
70
70
70
70
70
75
75
75
75
75
75
75
80
80
80
80
80
80
80

10

5

35

30

25

20

15

10

5

30

25

20

15

10

5

25

21

17

13

9

5

1

20

17

14

11

8

5

2

30

35

0

5

10

15

20

25

30

0

5

10

15

20

25

0

4

8

12

16

20

24

0

3

6

9

12

15

18

.0653 .0197
.0477 .0149
.1296 .0375
.1176 .0343
.1053 .0308
.0921 .0271
.0778 -0232

.0324
.0302
.0421
.0403
.0384
.0364
.0343
.0320
.0300
.0395
.0377
.0358
.0338
.0316
.0297
.0371

.0316

.0319
.0304
.0306
.0308
.0311
.0309
.0316
.0319
.0307
.0309
.0311
.0314
.0316
.0319
.0309
.0310
.0313
.0314
.0320

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

.0065 4 451

28

.0068
.0069
.0067
.0069
.0068

4.719

29

2.987

30

3.159

31

3 . 342

32

3 . 5.34

33

.0066 3.74fi

34

.0629
.0465
.1122
.1005
.0881
.0745
.0605

.0190
.0146
.0326
.0296
.0261
.0224
.0185

.0065
.0067
.0067
.0068
.0069
.0065
.0064
.0066
.0071
.0068
.0067
.0069
.0069

3.963

35

4.198

36

2.831

37

2.993

38

3.169

39

3.345

40

3.554

41

.04511.0143

3.745

42

.0971
.0868
.0771
.0668
.0557
.0443
.0323
.0814
.0743
.0669
.0594
.0514
.0432
.0351

.0285

2.684

43

.0260|.0338
.02311.0342
.0203 .0321
.0176 .0315
.01441.0295

2.800

44

2.932

45

3.062

46

3.205

47

.0319il.000
.032011.000

.006913.350

48

.0109
.0244
.0223
.0203
.0181
.0162
.0142
.0114

.0279
.0348
.0338
.0328
.0316
.0304
.0294
.0282

.0067
.0068
.0066
.0068
.0069
.0066
.0068
.0066

3 . 503

49

.0315
.0320
.0319
.0319
.0320
.0322
.0321

1.000
1.000
1.000
1.000
1.000
1.000
1.000

2.546

50

2.631

51

2.718

52

2.812

53

2.906

54

3.005

55 . . . .

3.150

brickettes were molded, weighing from 25 to 30 grams iii
the burnt condition. For obtaining the electrical resist-
ance small dishes of the shape shown in Fig. 1 were jig-
gered. These dishes had a diameter of about 3 3/16 inch,
and a depth of V4 inch in the burnt state. All of the test
pieces were burnt in saggers in a coal fired down-draft
kiln, and special attention was paid to the observation of
the temperatures by distributing cones throughout the
kiln. The length of burning varied from 36 to more than
48 hours.

After burning, the porosity of the brickettes was de-
termined in the manner repeatedly described in the Trans-

8 VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

actioiis of this society. In addition, the speeilic gravity of
the pulverized brickettes was determined by means of the
pyciiometer. After grinding the porcelain specimens in
the jaw crusher and in iron mortars, pains were talvcn to
remove the metallic particles by means of a magnet. The
true specific gravity of the bodies was determined primar-
ily for the pui'i^ose of obtaining the volume of the enclosed
pore space, for which it was hoped to establish some rela-
tion as regards temperature and content of feldspar.

The specimens for the electrical tests ^^ere selected
by inspection from the burns, Avhich resulted in apparently
vitrified bodies. The puncture tests were conducted in the
Electrical Laboratoiy of the University of Tllinois, under
the direction of Mr. Thomas H. Amrine. The arrangement
of the specimen for the test is shown in Fig. 1. The read-
ings of the voltmeter below 10,000 volts were not as
accurate as was desired, and it would have been better if
the thickness had been greater, as the instrument was de-
signed for readings above 10,000 volts.

The results of this work expressed in graphical form,
ill which they tell their own story, are discussed under
the following headings :

1. Composition areas showing the mixtures resulting
in vitrified bodies at several temperatures. All bodies
alisorbing not more than 0.1% of water, by weight, upon
boiling in vacuo are considered vitrified. The compositions
are plotted by means of triaxial diagrams and are ex-
pressed in simple percentages of clay, feldspar and flint.

2. Composition areas plotted in a rectangular co-
ordinate system, the abscissae representing molecular
equivalents of the EO constituents and the ordinates mole-
cules of silica.

This system is used simply as a means of classification
for the purpose of outlining the general effect of chemical
composition. The writers fully recognize the fact that we
are here not dealing with homogeneous igneous compounds
and solutions, owing to the fact that the materials are not

VITRIFICATIOX RANGE AND Dl-EL.ECTRIC BEHAVIOR. i)

reduced to maximum fineness and that the viscosity is still
so great that no appreciable deformation of the burnt
specimens is observable at the temperatures employed.
Ho\\ ever, the fact remains that these mixtures ai-e blended
sufficiently intimate and soften enough to bring about
jnolecular interaction which, though far from having
reached equilibrium conditions, still justifies the use of
chemical nomenclature. It might be suggested that the
mineral composition be used as the basis of comparison,
but this likewise is open to the objection that we must
assume the presence of clay and feldspar corresponding to
theoretical formulre. From the standpoint of fact there
should be no objection to the use of tlie empirical formula
based as it is upon knowledge of a positive kind, the re-
sults of the chemical analysis. The l)0undar3^ curves in the
nature of the case are fixed by the burning conditions
which prevailed in carrying out these tests. Longer burn-
ing would tend to lower the vitrification temperature,
shorter burning would raise it.

3. In this group the apparent porosity at cone 9-10
is correlated with the feldspar-fiint content for 50 and
60 9f of clay.

4. Tlie (liagranis of lliis group illustrate the decrease
in porosity with increasing temperatures, i. e., they ex-
press the progress of viti-ification. These data are pre-
sented for varying fehls]tai'-fiint contents for both 50 and
00% of clay.

5. In these diagrams the decrease in true specific
gravity with increasing temperatures is shown for various
proportions of feldspar and Hint. The data of two series
with 50 and C>0^( of clay are presented. In previotis work
the fact that the true specific gravity of silicates decreases
as fusion progresses has been sufficiently brought out and
is here again illustrated. It might be said in this respect
that the determination of the true specific gravity was
decided upon principally for the purpose of calculating
the volume of the enclosed pore space, the "bleb" structure

10

VITRIFICATION RANGE AND DI-ELECTRJC BEHAVIOR.

of Purdy, but on plotting the curves it was found that
these relations were exceedingly irregular. It was shown
roughly that the enclosed pore space increased with the
feldspar content but it also appeared that the initial struc-
ture of the body, the varying degree of density attained in
molding, the amount of water employed, etc., is an im-
portant factor in this respect, which precluded the possi-
bility of showing any simple correlation.

6, In this group the composition of the bodies is
again presented by means of triaxial diagrams, and the di-
electric strength shown by the jiggered vitrified test pieces

TRANi AM. CER.SOC VOUIl

BLEININQER ):5TULL.

is indicated b3^ areas representing voltages per mm. of less
than 10,000 volts, of 10000-14000 volts and of from 14000-
18000 volts. Table II shows the voltages for the various
mixtures at several burning temperatures.

VITRIFICATION RANGE AND UI-EIjECTRIC BEHAVIOR.
TABLE II.

11

Total Punc.

Thickness

Punc. Ya in.

Punc.

No.

Voltage

mm.

Volts

Volts per mm.

A 1

12+

45,820

3.15

46,188

14,546

13

26,680

3.13

27,080

8,581

2

61/2

37,480

2.52

47,225

14,873

9

34,400

2.70

40,454

12,741

12+

35,100

2.83

39,382

12,403

3

9

32,600

2.62

39,316

12,400

12+

37,000

2.70

43,512

13,700

13

27,000

2.64

32,454

10,227

4

9

38,600

2.95

41,534

13,085

12+

53,970

2.97

57,640

18,172

13

30,640

2.66

36,584

11,520

5

10

40,700

3.08

41,962

13,214

13

37,800

2.48

48,422

15,322

12+

55,040

3.13

55,866

17,585

13

34,780

2.74

40,310

12,700

6

12+

36,240

2.79

41,314

12,989

13

41,100

2.96

44,059

13,885

7

12 +

13

12

47,960

2.94

51,749

16,313

8

33,500

3!06

34,V73

i6,944

12+

33,500

3.13

34,003

10,703

13

28,500

3.08

29,384

9,285

9

12 V2

13

13

35,860

3.03

37,545

11,835

10"

• • • •

11

121/2

13

38,'606

3!oi

46,685

i2,V24

12

61/2

49,620

2.72

57,956

18,242

10

45,610

2.92

49,578

15,620

12+

31,490

3.00

33,317

10,496

13

12 +

38,980

3.06

40,461

12,738

13

43,400

3.02

45,570

14,371

14

12 +

39,170

3.03

41,011

12,927

15

12+

40,120

2.94

43,290

13,646

13

39,360

2.98

41,918

13,208

16

12+

43,580

3.07

45,236

14,195

13

38,120

3.24

37,358

11,765

17

12

32,600

2.70

38,338

12,074

12+

38,280 1

2.95

41,189

12,976

121/2

47,780

2.79

54,469

17,125

13

27,750 1

2.93

30,053

9,471

18

12

23,700

3.06

24,601

7,745

121/2

13
12

23,700 1

3.10

24,269

7,645

19

i

i

13

20

12

121/2

12

VITRIFICATION RANGE AND DI-ELECTRIC I'.EHAVIOR.

TABLE II— Continued.

Total Punc

Thickness

Punc. !4 in.

Pjnc.

No.

Cone

Voltage

mm.

Volts

Volts per mm.

A 21

12 +

43,660

2.82

49,161

15,482

121/2

38,980 -

2.80

44,142

13,914

13

40,500

2.70

47.628

15,000

22

6

40,500

2.91

44,185

13,917

12+

41,100

2.76

47.306

14,891

13

32,750

2.74

37,976

11,952

23

12+

41,100 1

2.76

47,306 1

14,891

13

37,000

2.85

41,218

12,982

24

12 +

44,300

2.89

48,641

15,328

13

40,100

2.93

43,328

13,686

25

12+

35,660

2.91

38,905

12,254

13

44,490

2.70

52,320

16,477

20

13

• • • •

27

13

28

13

29

12+

3 7, 8 00

2 '.66

45.133

14,210

121/2

41,700

2.60

50,916

16,038

13

33,500

2.62

40,568

12,786

30

12 +

35,100

2.92

38,154

12,020

121/2

44,680

2.77

51,248

16,130

13

43,940 .

2.87

48,598

15,310

31

13

42,860

2.91

46,760

14,732

32

121/,

38,280

2.94

41,304

13,020

13

38,280 ,

2.80

43,448

13,671

33

121/2

31,320

2.88

34,515

10,867

13

26,840

2.76

30,893

9,'f24

34

121/,
13

'.'.'.'.'.'.

35

13

36

11

39,360

2.84

44,004

iiVsg

121/2

41,700

2.83

46,787

14,731

37

6

26,040

2.57

32,160

10,132

11

43,580

2.82

49,071

15,453

13

33,050

2.78

37,810

11,888

38

11

26,840

2.96

28,772

9,067

12

23.700

2.81

26,781

8,434

13

39,360

2.97

42,036

13,253

39

12

23,700

2.54

29,625

9,330

121/2

23,700

2.87

26,212

8,257

13

33,050

2.73

38,470

12,106

34,140

2.81

38,578

12,146

40

12

121/2

13

41

12

121/2

13

25,060

3!73

21,351

* 6,Vl8

42

11

29,660

3.17

2 9, '7 19

'9,356

121/2

34,140

3.21

33,764

10,636

13

39,740

3.07

/I '"-!

l?.9ir,

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

13

TABLE II— Continued.

No.

Cone

Tot.lPuuc.
Voltage

Tbicki.es3
mm.

1 Punc. V& in.
: \'olts

Punc.
Volts per mm.

A 43

11

32,600

3.27

30,655

9,970

12

45,060

3.08

46,467

14,630

13

29,940

3.18

29,937

9,415

44

12

30,980

3.26

30,175

9,503

121/2

38,280

3.36

36,175

11,393

13

23,700

3.23

23,297

7,338

45

6

30,300

3.30

' 29,149

9,182

12

25,400

3.32

24,282

7,651

121/2

13

22,'680

3.37

2i,*.565

' h'j'i'o

46

121/2

25,400

3.47

23,241

7,323

47

121/2

13

13

23,700

3.46

21,757

6,850

48

49

13

37,960

3.10

38,871

i2,'245

50

13

36,240

3.31

34,754

10,948

51

13

39,740

3.06

41,250

12,987

52

IS

29,220

3.15

29,453

9,276

53

13

26,200

3.24

25,676

8,086

54

13

26,040

3.36

24,607

7,750

55

13

23,700

3.42

21,993

6,930

B 1

10%

34,620

2.77

39,659

12,498

11

33,500

3.08

34,539

10,876

12

36,430

2.83

40,874

12,873

121/2

32,300

2.60

39,438

12,423

2

6Vz

48,300

3.30

46,469

14,636

10

45,250

3.26

44,074

13,880

10 y2

46,010

3.21

45,504

14,333

3

evz

42,300

3.20

41,962

13,220

10

43,760'

3.33

41,894

13,141

101/0

51,700

3.24

50,666

15,957

4

6 1/2

48,520

3.27

45,113

14,838

81/2

48,960

3.31

46,953

14,770

101/2

50,280

3.55

44,950

14,163

5

814

49,400

3.25

48,264

15,200

11

48,960

3.28

47,393

14,927

1214

42,300

3.32

40,439

12,741

6

8V0

43,400

3.30

41,751

13,152

11

43,220

3.19

43,080

13,548

1214

47,460

3.40

44,328

13,960

7

81^

38,980

3.12

39,682

12,494

11

41,900

3.02

43,995

13,874

1214

39,170 1

3.09

40,228

12.676

8

10

35,670 1

3.23

35,064

11,043

12+

28,860

3.30

27,763

8,745

121/4

48,740

3.12

49,617

15,622

9

12

36,430

3.12

37,086

11,676

12+

48,300 1

3.20

47,914

15,094

10

12

33,200 1
1

3.54

29,780

9,380

14 VITRIFICATION RANGE AND DI-EfiECJTRIC BEHAVIOR.

TABLE II— Continued.

Total Punc.

Thickness

Punc. /^ in.

Pane.

No.

Cone

Voltage

mm.

Volts

Volts per mm.

B 11

12

1

24,720 i

3.60

21,793

6,866

12

61/2

40,500

3.21

40.055

12,617

8 1/2

40,700

3.23

40,008

12,600

12%

30,470

3.34

28,977

9,123

13

6V^

44,300

3.21

43,713

13,800

8y2

39,930

2.95

41,965

13,535

12+

25,720

3.46

23,611

7,404

14

61/2

38,600

3.31

37,017

11,360

9

29,580

3.17

29,639

9,331

10

31,830

3.26

31,002

9,764

12+

32,750

3.36

30,949

9,747

15

61/2

41,700

3.33

39,740

12,523

10

45,530

3.26

44,346

13,963

12

38,280

3.54

34,337

10,814

16

61/2

47,460

3.26

46,226

14,558

81/2

58,830

3.22

58,006

18,276

12

54,180

3.32

51,796

16,320

17

81.^

40,310

3.46

37,005

11,650

10

33,660

3.25

32,886

10,357

12

49,350

3.09

50,682

15,971

12+

49,180

3.12

50,065

15,763

18

12

53,920

3.18

53,870

16,956

12%

53,340

3.02

56,007

17,662

19

12

36,050

3.09

37,023

11,666

121/4

33,980

3.05

35,373

11,141

20

12

39,360

3.47

36,015

11,343

121/4

29,760

3.24

29,155

9,186

121/2

41,300

3.35

39,152

12,330

21

6V2

45,630

3.19

45,448

14,304

9

44,490

3.17

44,579

14,035

12 +

34,140

3.26

1 33,252

10,472

22

6 1/2

47,620

3.11

48,621

15,312

9

44,870

3.02

1 47,114

14,858

12+

42,860

3.08

1 44,189

13,915

23

8 1/2

38,600

3.06

1 40,067

12,614

12+

44,680

3.15

i 45,037

14,184

i2y2

36,620

1 2.59

j 44,860

14,140

13

42,100

2.98

1 44,839

14,127

24

8%

51,100

3.06

1 53,042

16,700

12+

40,900

1 3.04

1 42,700

14,046

1 13

55,040

3.22

1 54.269

17,100

25

1 8 1/2

39,450

3.06

1 40,949

12,802

1 12 +

45,440

1 3.17

1 45,531

14,334

1 121/2

27,900

! 2.76

1 32,113

10,110

1 13

43,940

1 3.04

1 45,873

14,454

26

1 8 1/2

50.280

1 3.02

1 52,994

16,649

12+

46,200

1 3 . 13

1 46,893

14,760

13

1

40,100

! 2.95

1 43,148

13,614

VITRIFICATION RANGE AND DI-ELECTRIC T^EHAVIOR.

15

TABLE II— Continued.

1

Cone

Total Punc.

Thickness

Punc. ?/i in.

Punc.

N,. ,

Vokage

mm.

Volts

Volts per mm.

B 27

12

27,900

(

3.17

27,956

8,801

12+

46,830

3.07

48,422

14,928

121/2

55,480

3.13

56,312

17,725

13

45,250

3.04

47,241

14,885

28

12 +

33,810

3.27

32,830

10,340

121/2

34,140

3.16

34,311

10,804

13

33,050

3.22

32,627

10,264

29

eva

47,040

2.96

50,427

15,892

9

43,310

3.12

44,090

13,881

12+

32,000

3.40

29,888

9,412

30

61/2

44,680

3.07

46,199

14,554

9

42,500

3.06

44,115

13,888

12 +

41,900

3.35

39,721

12,508

31

6%

40,120

3.16

40,320

12,728

9

36,620

3.14

37,060

11,662

12+

28,500

3.09

29,270

9,223

13

36,620

3.12

37,279

11,737

32

7%

49,620

3.07

51,307

16,163

9

38,440

2.80

43,630

13,730

12^4

51,500

3.25

50,316

15,850

13

35,100

2.85

39,101

12,315

33

1%

44,120

3.10

45,179

14,232

12

42,860

2.93

46,417

14,631

121/,

43,940

3.17

44,028

13,861

34

12

44,680

2.96

47,897

15,894

12 +

48,740

3.15

49,130

15,473

35

12

35,480

3.22

34,981

11,020

12+

45,440

3.06

47,167

14,850

36

61/2

30,120

3.02

31,626

9,973

T%

43,220

3.03

45,251

14,264

1214

33,200

2.96

35,590

11,216

37

6

42,860

3.02

45,003

14,192

7%

35,100

3.13

35,627

11,215

12 +

37,480

3.24

36,730

11,537

38

6

32,150

2.95

34,593

10,900

61/2

30,980

2.98

32,995

10,396

9

50,280

2.90

55.057

17,340

12

36,620

3.23

35,997

11,338

12 +

43,580

2.97

46,543

14,673

39

9

41,800

2.97

44.642

14,110

12

45,250

3.13

45,929

14,457

40

12

40,700

3.05

42,369

13,344

41

12

38,980

3.03

40,612

12,864

42

6

36,810

2.91

40,160

12,650

81/2

34,940

3.05

36,373

11,455

12

36,430

2.90

39,891

12,560

43

12

43,400

3.12

44,181

13,910

12+

40,500

3.21

40,055

12,617

I

12 y2

53,340

3.04

55,687

17,546

16

VITRIFICATION RAXGE AND DI-ELECTRIC BEHAVIOR.

TABLE II— Continued.

1

Total Punc.

ThickQcss

Punc. Vi ID.

Punc.

Xo.

Cone

Voltage

mm.

Volts

Volts per mm.

1

B 44

12 +

45,060

2.98

47,989

15.121

12^

47,040

2.93

50,944

16,054

45

12

43,220

3.00

4.5,727

14,406

12+

44,490

2.87

49,206

15,502

46

12

44,870

3.08

46,261

14,570

12+

51,900

3.06

53,872

16,961

12 y*

48,040

3.06

49,865

15,686

47

12

34.140

2.17

49,947

15.733

12 Va

37,960

2.04

58,956

18,608

48

12

36,240

3.07

37,472

11,805

12%

34,460

2.89

37,837

11,924

49

6

40,500

3.01

42.687

13,455

SVa

38.280

2.95

41,189

12,976

12

38,280

2.91

41,763

13,155

50

81-^

43,400

2.85

48,348

15,228

12

43,400

2.97

46,351

14,613

51

12

46.200

2.76

53,176

16,740

1214

56,800

2.68

67,308

21,194

52

12

38,280

3.06

39.735

12,510

13

45,820

3.15

46.186

14,546

53

12

44,680

2.85

49,774

15,681

1214

37,160

2.91

40,542

12,770

13

52,500

3.06

54,495

17,157

54

12

38,980

2.66

46,542

14,654

12 Va

39,740

2.70

46,734

14,720

13

40,120

2.68

47,542

14,970

55

12%

44,680

2.83

50,132

15,788

13

45,440

2.78

51,983

16,345

C 1

12

22,000

3.13

22,330

7,028

2

11

45,440

3.35

43,077

13,564

12

45,440

3.20

45,076

14,200

3

7%

30,980

3.27

30,082

9,474

11

44,120

3.28

42,808

13,451

121/4

46,200

3.12

47,031

14,808

4

11

36,050

2.88

39,727

12,518

12

44,300

2.18

50,059

15,765

5

11

37,960

3.34

36,100

11,365

12

41,100

3.22

40,425

12,764

1 12+

48,300

3.00

51,101

16,100

6

( 11

54,600

3.22

53,836

16,956

12%

53,760

3.16

54,029

17,013

12 Vz

44,680

3.26

43,517

13,706

7

11

45,820

3.16

47,038

14,500

12

60,060

3.77

50,571

15,931

8

12

27,300

3.25

26,672

8,400

9

12

12%

_

10

12

_

11

12

3. 5 ,'4 80

3.54

3i,'826

10,023

VITRIFICATION RANGP: AND DI-ELECTRIC BEHAVIOR.

17

TABLE II— Continued.

No.

Cone

Total Pane.
V'oliaje

Thickness
mm.

Pjnc. 'A in.
Volts

Punc.
Volts per mm.

C 12

7%

1

25,-580

1

2.54 i

1

31,975

10,071

11

43,940

2.50 i

55,804

17,576

No Cone

46,200

2.65

55,343

17,434

13

11

42,300

2.44

55,575

17,374

121/2

33,820

2.32

45,166

14,577

No Cone

1

marked

42,100

2.60 1

51,404

16,192

14

11

41,100

2.76 1

47,806

14,891

IS

47,040

2.52

59,270

18,666

No Cone

44,300 1

2.49

56,533

17,791

15 1

11

31,320

2.73

36,457

11,469

121/2

46,410

2.71

54,393

17,125

16

7%

29,940

2. 58

36,826

11,605

11

37,100

2.54

46.450

14,630

121/2

55,920

2.51

70,739

22,278

17 j

121/,

31,660

2.. 55

39,317

12,415

18

12

121/2

19

121/2

13

'.'.'.'.'.'.

20

12%

21

12i/o

32,600

2.47

41.923

13,198

22

13

30,300

2.63

36,522

11,521

23

121/2

33,200

2.31

45.617

14,372

13

22.680

2.61

27,579

S,G90

24

12 V2

34,140

2.71

40,012

12,598

25

121/2

28,050

2.63

33,829

10,666

26

12
13

27

12

12 +
13

::::

28

12 +
No Cone

29

121/2

29,940

2.68

3.5,479

ii,172

30

12

32,300

2.24

45,769

14,420

121/,

28,050

2.29

38,877

1 12,250

13

35,100

2.36

47,245

! 14,877

31

12

1

121/2

32,600

2.55

40.587

12,784

13

32,000

2.31

1 43,968

13,853

32

12

25,720

1 2.42

1 33,770

10,628

13

23.700

2.15

! 34,881

11,023

33

12

1

!

1

34

! 12

1

35

12

i IB

1

36

12

24,720

2.39

.33.828

' 10,343

37

12

24,210

2.73

! 28,180

1 8,872
1

18

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

TABLE II— Continued.

Total Punc.

Thickness 1 Punc. 5'8 in. 1

Punc.

No.

Voltaee

mm

Volts

Volt» per mm.

1

C 38 1

13

30,640

2.35

41,395

13,038

39

13

27,300

2.2C

1 37,838

11,921

40

12

1

41

12

1

42

12

28,050

2.3f

> ! 37,755

ii,886

13

27,300

2.3J

L 1 37,500

11,818

43

12

22,680

2.4J

1 29,892

9,410

44

12

45

12
13

!

46

12

47

12

i

48

12

49

12

22,060

• 2.2]

L 31,592

9,955

50

12

51

12

52

12

53

12

54

12

55

12

D 1

6

121/2

13

2

6

29,040

2.1'

1 42,385

13,382

8V2

28.200

2.1

J 1 41,257

13,000

12+

32,600

2.1

? 1 48,574

15,305

3

6

31,070

2.3

? 1 41,416

13,055

81/2

31,660

2.3

5 ] 42,203

13,302

124-

28,860

2.7

J 1 33,593

10,571

4

6

29,940

2.4

7 38,500

12,121

81/2

31,830

2.4

B 40,774

12.835

12

39,740

2.3

S 1 53,490

16,839

12 +

28.200

2.5

2 1 35,532

11,190

5

81/0

33,350

2.3

i i 45,423

14,313

12

30,300

2.1

5 .1 44,722

14,093

6

SYz

33,:i00

2.1

S i 48,372

15,230

12

34,780

1 2.1

5 1 51,335

16,177

13

29,400

> 2.3

5 1 39,620

12,510

7

8%

28,680

2.2

8 1 39,923

1 12,580

12

H7,160

2.4

2 1 48,791

15,351

13

35,670

2.2

5 ! 50,295

15,851

8

7%

30,810

2.1

2 1 46,153

14,533

12

30,810

i 2.3

2 1 42,148

1 13,280

121/2

31,510

! 2.2

2 1 45,059

i 14,194

13

33,500

2.7

9 i 38,190 .

12,007

9

SVz

31,660

2.2

8 ! 40,071

13,886

12

36,240

1 2.1

4 1 53,780

16,934

10

1 12+

! 29,220

2.4

1 1 38,512

12,124

1 12 1/,

26.680

2.3

0 1 36,818

1 11.600

1 n

27.300

' 2.2

6 1 38,329

1 12,080

VITRIFICATtON RANGE AND DI-EbECTRTC BEHAVIOB. 19

TABLE II— Continued.

Total Punc.

Thickness |

Punc. Vs in.

Punc.

No.

1

Cone

Voltage

mm.

Volts

Volts per mm.

D 11

13

12

evz

34,466

2.18

56,268

15,867

8 1/2

28,860

2.14

42,828

13,486

12

36,620

2.22

52,367

16,495

13

8V2

39,740

2.38

52,973

16,699

9

27,300

2.22

38,039

12,297

12

30,300

2.13

45,147

14,225

11

121/2

27,000

2.09

41,013

12,918

6

29,940

2.21

42,994

13,547

7%

35,860

2.09

54,471

17,158

8%

37,320

2.10

56,428

17,771

15

6

25,560

2.22

36,551

11,513

7%

30,470

2.04

47,411

14,936

12

28,500

2.72

31,770

10,477

16

734

32,900

2.17

48,133

15,161

8V2

25,720

2.12

38,529

12,132

12

36,810

2.56

45,644

14,378

13

31,320

2.31

43,034

13,558

17

7%

30,640

2.19

44,428

14,000

12

30,300

2.19

33,935

13,825

12 +

32,750

2.18

47,717

15,023

13

37,320

2.30

51,502

16,226

18

81/2

29,940

2.06

46,138

14,534

12 +

33,050

2.18

48,154

15,160

13

33,500

2.16

49,245

15,510

19

12 +

31,050

2.27

43,208

13,679

121/2

34,140

2.04

53,122

16,735

13

32,900

2.28

45,797

14,430

20

121/2

13

37,320

2 '.76

42,955

i3,'522

21

6 1/2

32,000

2.62

38,752

12,214

8 1/0

39,450

2.60

48,168

15,173

12 +

42,100

2.56

52,204

16,445

22

61/2

26,360

2.19

38,222

12,037

7%'

31,660

2.19

45,907

14,457

12 f

33,500

2.37

44,890

14,135

23

6

9
12+

29,580

2.32

46,465

12,750

26.'686

2!68

46,714

i2,'827

13

31,660

2.27

44,261

13,950

24

8y2

29,940

2.23

42,635

13,426

12

38,980

2.29

41,358

13,037

12-)-

30,300

2.36

40,784

12,398

25

12 +

37,960

2.09

57,661

18,162

121/2

36,810

2.06

56,724

17,869

13

36,620

2.27

51,195

16,132

26

12+

43,220

2.70

50,827

16,008

13

42,860

2.75

49,460

15,585

20 VITRIFICATION RANGE AND DI-ELECTRIC BliHAVIOR.

TABLE II— Continued.

Total Pane.

Thickness

Punc. yi in.

Pane.

Nj.

Cone

Voltage

mm.

Volts

Volts per mm.

D 27

12

27,900

2.68

33,002

10,411

12+

39,740

2.60

48,523

15,245

13

38,980

2.58

47,945

15,110

28

13

29,220

2.69

34,480

10,862

29

6
9

12

36,240

2.52

45,662

14,381

12 +

35,100

2.62

42,516

13,397

30

6
6%

12

36,620

2^48

46,910

14,766

12 +

37,960

2.71

44,472

14,007

13

46,010

2.62

55,218

17,561

31

61/2

....

12

36,620

3!i3

37,169

ii,Voo

13

35,480

2.84

39,667

12,493

32

6

43,940

2.55

54,705

17,231

11

46,200

2.49

58,951

18,554

12

35,100

2.49

44,788

14,092

124-

42,300

2.73

49,237

15,494

121^

49,180

2.58

60,491

19,062

13

39,360

2.71

46,130

14,524

33

11

27,600

2.78

31,574

9,928

12

32,600

2.63

39,316

12,375

12i/o

45,060

2.61

54,793

17,263

34

10%

29,040

2.60

35,458

11,170

121/2

36,620

2.56

45,409

14,305

13

37,960

2.67

45,135

14,217

35

IOV2

12 +

....

121/2

25,720

2!8r

28,446

" 8,961

36

6 1/2

11

36,240

2^24

51,3.52

16,180

121/2

32,450

2.67

38,583

12,154

13

39,740

2.66

47,450

14,940

37

6 1/2

101/2

26,680

2!75

30,V89

9,702

12+

28,500

2.62

34,514

10,878

13

24,380

2.68

28,890

9,097

38

QV2

101/2

30,030

2!72

35,075

ii,140

13

31,660

2.79

36,092

11,348

39 1

ini'i

25,920

2.70

30,247

9,526

i

12 -C

32,900

2.63

39,677

12,510

1

121/2

32.600

2.60

39,805

12,540

1

13

33,820

2.83

37,941

11,950

40 1

10 v.

1

;

121/i

32,600

2.83

37,846

li.Vio

1

13

26,360

2.65

31,569

1

9,947

I

VITRIFICATIOX UAXGE AND DI-ELECTRIC BEHA\ lOR.

21

TABLE II— Continued.

Toal Punc.

Thickness

Punc. Vs in.

Punc.

Voltage

mm.

Volts

Volts per mm.

D 41

1

! 10-/2

I

12 1/2

27,606

2.86

36,636

9,650

13

1 27,000

2.63

32,562

10,266

42

6y2

'

13
11

23,700

2.74

27,468

8,656

43

23,V()6

2.68

28,085

8,840

121/2

29,400

2.56

36,456

11,484

13

30,640

2.66

36,584

11,519

44

11

25,230

2.96

27,047

8,524

121/0

30,120

2.70

35,421

11,192

13

27,150

2.64

32,634

10,284

45

101/^
11

,

;;;;;;

12+

32,000

2.51

40,480

i2,749

45

12^

34,780

2.55

43,301

13,640

13

32,900

2.54

41,125

12,953

46

11

13

32,666

2.52

41,076

12,932

47

121^

23,700

2.64

28,487

8,977

13

24,200

2.54

30,250

9,527

48

121/2
13

49

61/0
1014

13

27,900

2.76

32,113

10,109

50

101^

121/2

23,700

2.69

27,966

8,816

13

22,000

2.48 1

28,182

8,871

51

10%
11

1

13

28,200

2.58

34,686

16,936

52

121/2

24,760

2.67

29,440

9,273

13

28,350

2.50 1

36,005

11,340

53

121/2

25,060

2.69 :

29,571

9,316

54

12 V2

.... 1

13

25,466

2.84 1

28,397

8,944

55

121/2

.... 1

13

27,750

1

2.63 1

1

33,467

16,552

Vitrification Range.

A. Georgia Kaolin. In Fig. 2 we find plotted tliree
temperature areas, cone 7-9, cone 0-10, and cones 10-13.
Brief inspection shows that this kaolin has a conipara-
tivelv large range of compositions yitrifying below cone 10.

22 VITEIPICATION RANGE AND DI-ELECTRIC BEHAVIOR.

This is again IJlustrated b}- the fact that within this tem-
perature range a feldspar content as low as 18 per cent,
with 51% of clay, is shown. With a temperature corres-
ponding to cone 13 and the same clav content, the feldspar
may be cut down to 14%. The dividing line between the
cone 9-10 and tlie 10-13 areas shows a decrease in feldspar
and a corresponding increase in flint from the 25% to the
20% feldspar line.

B. Tennessee Ball Clay, Pig. 3. The less refractory
character of this clay is indicated by the large range cov-
ered by the temperature area below cone 10. Near the
50% clay line the feldspar drops as low as 13%, and at the
00% clay line a feldspar minimum of 5% is shoAvn at a
temperature not exceeding cone 10. It is evident, there-
fore, that in a body the feldspar content may be the lower
the greater the content of ball clay.

C. The North Carolina Kaolin offers quite a contrast
to the last material, inasmuch as its vitrification area is
quite small at temperatures up to cone 10. Fig. 4. The
range is decidedly increased at the higher temperatures,
and at cone 131/2 it is possible to cut down the feldspar
percentage to below 15%, while at cone 10 the minimum
feldspar content is 23%.

D. The EnfjUsh China Clay, Fig. 5, differs from tlie
preceding clays in that its vitrification boundaries slope
far more gradually in spite of the fact that its alkali con-
tent is not greater than that of the North Carolina kaolin.
With decreasing clay and increasing flint content the spar
gradually diminishes until, with 50%> clay, the feldspar is
reduced to 15% at cone 9-10 to 5% at cone 10-11. It is
evident, therefore, that this material differs considerably
from similar American claj^s in this respect, due to its
structure or fineness of grain. Its vitrification area is
quite large.

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR. 23

BLEININGEBi: STULU

TnANS. AM. CER.SOC.VCLW

LEIN1N0£R X STULL.

24 VITRIFICATION RANGE ..VND DI-ELECTRTO BEHAVIOR.

TR/'-'S, AM. CER. SOC VOL.Xll

BLEININCER X STULL

TRANS. AM. CER. &0C. VOL XII

SLEININGER k STULL.

VITRIFICATION RANGE AND DI-ELEGTRIC r.EJIAVKJK. 25

Chemical Vitrification Range.

A. Georgia Kaolin. From this cliagriim. Fig. 0, we
learn that the minimum and maximnm limits of SiOo for
cone 9-10 are 5.00 and 3.1 molecular equivalents. The

TRANS. AM. CER. t^OCVOLAl.

BLEININfiER k 5TULL.

5.80

5.60
5.40
b.lO
5.00

4.60
4.40
4.Z0

.■^3.80
^3,60
^ 3.40

Z.40
2.20-

2.10

O

1

Fio.6 ^

—

(

J

1 1 1

1

<

^

1

/

^

^

0

/

A

0

y

'

/

H

o

o

/

o

o

^

/

o

V

'

1

, ^

\

1 r

/

^Cofie&l

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^ Cones 3 -10

r/

o

\

1 , ,

\

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1

/

(

_

_

^_

o

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_,

5

^

_

—6

_

^

/

—

—

—

~o"

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V

^

V,

^

—

0

—

—

^

=

—

-

—

—

O

,

^

^

°^

c

^

k.

,05 .06 .07 .03 .11 .13 .15 .17 .13 .21 .23 .25 17 13
Equivalents HO . "^i^O^- /.

.31 2y

minimum RO for the same temperature is 0.18. At cone
13 the maximum SiO. is 5.42 equivalents, the minimum
2.7, while the minimum RO is practically 0.12 equivalents.
B. The Tennessee Ball Clay areas, Fig. 7, appear to
be decidetlly irregular in chai'acter. It is noted that at
cone 9-10 the maximum SiOo is decidedly higher and the
iiiinimum quite lower than for tlie preceding clay, the
limits heing 5.7 and 2.6 respectively. It is a curious fact
tliat the minimum RO is much less than in the Georgia
kaolin, it being 0.14 at cone 10 and 0.09 at cone 13. It
would seem then that tlie ferric-oxide which is not in-
cluded in the RO is a decided factor in bringing about

26

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

vitriflcation in this clay. Wliile the total FooOa in the
ball clay is not much greater in amount than in the Geor-
gia kaolin, it is fair to assume from the physical appear-
ance of the former that the iron oxide is disseminated
more uniformly and is more thoroughly incorporated in
the clay substance. As to the peculiar shape of the vitri-
tication areas it is evident that they permit of no general-
ization, and must be ascribed to differences in the heat
treatment which are practically inevitable under the

TRANS, AM.CER.SOC.VOLXII.

BLEININuER k STULL

6.00
■5.80
5.60
5.+0
5.20
3.00
4.80
4.60
4.40
4.20

'O 3.80

^ifco

I 5.40
g 3.20
■^ 3.00
^l.U
'^ Z.60

240

ZiO

"".OB .06 .07 .09 .11 .13 .15 .17 .19 .21 .23 25 .27 .2? .31 .51

Equivalents nO ai^O.-l

usual conditions of test kiln practice, even though all
possible precautions are taken.

C. More symmetrical conditions prevail with the
North Carolina Kaolin series. Fig. 8. At cone 940 the
highest SiOo content in these mixtures is 4.85 equivalents,
the minimum 3.40, while the minimum RO is 0.295. The
cone 12-131/2 area it will be observed is very large, indi-
cating that the proper development of such a kaolin body
would be obtained only at the higher temperatures, just as
was shown in the triaxial diagram.

o

/

no.r :

/

0

\

' 1

t

0

'

s,

— -,

-

/

^

o

,

o

(

/

/

0

i

o

k^

- 0

/

o

\

V Co7?es 7-J>

/

Cones 10-13

\

Cones 3-/0 ^

^

1

o

o

/

(

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-<».

o

>

o

\

o

/

o

J

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1

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y

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0

y

\^

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Cones 4-7

-^

/

1

/

o

(

/

4

'

0

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

27

fc.CO
5.80
5.60
5.+0
5.Z0
5.00
4.80
4.60

4.00

^ 3.e0^

I 3.

-^ 3.Z0

§ 3.00

'g^ IM

'^2iO

2.40

ZiO

2J30

TRANS. AM. CER. &0C. VOUO

BLEININfieR feSTULL.

>

1 1 1 1

' 1 1

1

1

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.05 .06 .C7

.09 .11 .13 .15 .17 .13 .21 23 .25
F-auivalertt6 FfO.

n B .31 .33

6.0C
550
5.60

TRANS. AM. CER SOC VOLXU,

BLtlNINGERiSTULL.

o

Fla.S

^

r^

'

5.20
5.00
4.80
4.60
4.40
4.Z0
4.00

o

/

/

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^

/

/

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^^3.60

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.05.06.07 .09 .11 .15 .15 .1"

Equivalents BO.

l\ .23 .25 11 .:? .31 .33

28

VITRIFICATION R.4NGE AND DI-ELECTRIC BEHAVIOR.

D. Fig, 9. The English China Clay limits for cone
10-12 are 5.40 maximum SiOo, 2.75 minimum SiOg and
0.16 minimum RO. For cones 12-13^,^ the maximum SiOs
is 5.55, the minimum SiOo 2.35, and the minimum RO
practically 0.11.

Porosity Coordinated with Feldspar-Flint Contents,
— the clay being kept constant, at cone 9-10.

TRANS. AM. CER. SOC VOLXII.

BLEININ6ER i STULL

^9
"^ 8

^

'^ 5

\

1 \

f^yo

\

\

f

\

\

V

\

\Z

\

I

i \

\ 1

\

\

V

\

\

\

^

. \

^

^

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1

\

\

\\

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•— ——

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___

,

±^

^

r?»

5
45

10
40

15
35

30

25
25

20

40

10

5% Flint

1. 50% Clay, Fig. 10. This diagram shows at once
the percentages of feldspar necessar^^ to bring about vitri-
tication at this temperature. For the Georgia kaolin this
point is about 24%, for the Tennessee ball clay less than
15%, for the N. 0. kaolin 25%, and the English China
clay about 15%. As far as the ball clay and the English

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

29

China clay are concerned, the feldspar-flint additions are
of the nature of refractory agents. The feldspar is dis-
tinctly a flux for the N. C. kaolin but very much less so
for the Georgia kaolin.

2. 60% Chui, Cone 9-10, Fig. 11. Here the true na-
ture of the various claj^s is more clearly represented, and
brief inspection shows that the N. C. kaolin is by far the

TRANS. AM. CER. 50C. VOL.XII .

BLEININGER i: STULL

19
18

17

15
14
13
12
|M

^9

\

l\- r- ..

TT , Ft a

\\ ^

\ \

\X A

\ \

1 \

t A ^

4 ^

% ^^"v

1 \

% d^

X ^~

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\ \

10
30

15
Z5

ZO
£0

Z5
15

30
10

A
D

iS%Felds/i.
5% Fliiit

most refractory material which even with maximum
amount of flux fails to produce a dense body at this tem-
l>orature. AVith 60*^^ clay any i)ossible combination of spar
and flint cannot bring about vitrification. The eutectic
]»oint of N. C. kaolin-spar as well as of N. C. kaolin — 75%
pure spar+25% flint mixture — is beyond cone 0-10.

30

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

Porosity-Temperature Diagrams.

I. 50% Clay.

Series A, Georgia Kaolin, Fig. 12. These curves pre-
sent the rate of vitrification, and we note that for the mix-
tures Nos. 2, 4, 6 and 8 vitrification proceeds most rapidly
between cones 4 and 6, while for Nos. 10 and 11 the same
action occurs only beyond cone 11.

It is fair to assume then that the active fluxing magma
in all bodies but No. 11 has a melting point between cones

38
36
34

3Z

^ (1

TRANS.

AM. CER.SOC.VOLXi;.

BLEININGER & STULL.

na/2

■v^

"^

-^

^. 2 ~50%Fdd6fianOZFlini

4.-40 : 10
6-30 " 20 »

>_^

[^\

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n

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2+
U

18

^16

■^14

^IZ

^10

^^ 8

6

4

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N(&

"■""--

8-ZO " 30 ^'

^

—

^m^ ^ -fS '•

' --

^^

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\

\

__^

\

s

^.^

\

\

N

\ ^

\,

\

\

^

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__4__

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s

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v\

\

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n\

\

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C

1

Cc

'?Tel

^

? (

5 /

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» 1

0

1 1

2 1

r

4 and 6, and it is entirely possible to find its composition
by running a series of the system 0-50% clay, 50-0% feld-
spar+flint. From the large part of the pore space filled
up during this short temperature interval it appears also
that the fluxing matter has a lower viscosity than at any
subsequent stage. For while at higher temperatures the
total amount of the igneous solution is greater as it en-
riches itself in silica and alumina, the viscosity increases
correspondingly, causing it to flow less readily and more
liable to form a bleb structure. It is for this reason that

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

31

TRANS. AM. CER. 5CC. VOLXII.

BLEINIINGER Sc STULL.

3^
30
Z8
Z6
14
II
20
18
16

^ 6

Ha J J

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/L—An „ in »

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10-10 '. fO '

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01 I Z 3 4 5 6
Cones

10 II \Z 13

TRANS. AM. CER. SOC. VCL.Xll

SLEININGER Jfc 5TULL.

0' I 2 3
Cove5

IZ 13

32

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

TrtANS. AM. CER. 50C. VOLXII .

BLEININQER & 5TULL.

38
36
34
It
30
28
Z6

7A

"~^>^

ri^jo

■"■^

X

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'v.Z -SO°oFelds[iariO''o Flint
4-4-0 " 10 >'
6-30 ■' 10 »
8-ZO " 30 "
3-15 '• 35 '•
10-10 >• fO '■
11- 5 " is »

\^

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I 13

TRAN5. AM. CER. 50C. VOL.WI.

BLEININOER k 5TULL

-I

—

rn?i~.

in % Fpt/isnrr r//??

/=//

lialt ' ' 22-35 ' 5 ^.

U

Z3-3D " 10 "
Z^-Z5 " 15 "
Z5-20 " 20 "
26-15 '> 25 '

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Cones

6 7

\Z 13

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR. 33

the addition of a small amount of lime is beneficial, inas-
much as it decreases the viscosity and hence reduces the
above tendency.

Series B. Tenn. Ball Clay. Fig. 13. Here the condi-
tions are very similar excepting that the greater impurity
of the clay causes the curves to start at lower porosities.
Like in the preceding and all subsequent series, it is evi-
dent that the fusing action of feldspar begins at quite a
low temperature.

Series C. N. 0. Kaolin, Fig. 14. The characteristic
feature of this cla}^, its longer vitrification temperature
range, is at once shown as is to be expected from such a
comparatively coarse grained kaolin. While the Georgia
kaolin in mixture No. 8 reaches vitrification betAveen cones
11-12, the N. C. kaolin of the same mixture barely ap-
proaches the vitrified state at cone 13. This points out a
useful function of this material which must not be lost
sight of, its ability to hold up a clay body. The more a
certain composition or shape has a tendency to deforma-
tion, the greater proportion of this kaolin c.ui be intro-
duced to counteract it.

Series D. Fnglish China Clag, Fig. 15. Tlie smooth
curves indicate well the character of the vitrification pro-
cess. It differs from the two preceding kaolins in that it
appears to bring about better vitrifying conditions, which
are not too abrupt between certain points, nor does it fail
to produce vitrification with a low feldspar content like
that of Xo. 10 of A and C. Its great fineness of grain
undoubtedly is a factor in this behavior.

II. 60% Clay.

Series A. Georgia Kaolin. Fig. 16. In this set of

curves the same observation is made as before, viz., the

' highest rate of vitrification is found between cones 4 and 7

but, as is to be expected, the vitrification temperatures

have been raised with the higher clay content.

Series B. Tenn. Ball Clag. Fig. 17. In distinction
from the preceding clay, the vitrification temperatures are

34

VlTRIP^IGATION RANGE AND DI-ELECTRIC BEHAVIOR.

THANS. AM. CER. sec. VOL.XII.

BLEINiNuER & STULL.

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Specific Gravity-Temperature Diagrams.

In figures 20, 21, 22, 28, 24, 25, 26 and 27 the fact
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VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

36

TRAN5.AM. CeR. &0C.\0LX1I

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VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR. 39

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40 VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

DI-ELECTRIC BEHAVIOR.

In Table II the voltages required to puncture the test
pieces are compiled, together with the burning tempera-
tures in cones. The voltages have been arranged in three
groups which are: Less than 10,000 volts per mm; from
10,000-14,000 volts per mm., and from 14,000-18,000 volts
per mm. These groups are shown in the triaxial composi-
tion diagrams. Figs. 28, 29, 30 and 31. Of each composi-
tion the specimen showing the highest resistance was se-

TRANS. AM. CER.SOC. VOLXM . , BLEININQER X STULL .

Fio.ZS

20 25 30 35 40 4S

Flint
Georgia Kaolin.

lected without regard to the burning temperatures. Tlie
di-electric punctures seemed to locate flaws in the body
structure with accuracy, and frequently the break would
occur some distance away from the electric contact,
through some jiggering defect. Eesults, in which punc-
ture was evidently due to a flaw, were rejected.

On comparing the di-electric strength diagrams it is
found that the maximum voltage group is by no means
restricted to a short range in composition but covers a

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR. 41

TBANS.AM. CER. SOC.VOL.Xll. ^ y-

BLEINlNGERkSTULL.

North Carolina Kaolin.

42

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

TRANS. AM. CER. SOC. VOLXII.

BLEININQER ic 5TULL

0 5 10 15 20 Z5 30 55 40 45

English China Clay.
large area, in each case roughly proportional to the vitri-
fication area. If this electrical test is acceptable, of which
the writers are not certain, since they have no familiar
knowledge of insulator testing, it would seem then that
an^^ well vitrified body, free from mechanical and burning
flaws, irrespective of composition, would be suitable for
insulation work as far as electrical resistance is concerned.
It is therefore more a matter of obtaining sound vitrifica-
tion than of a certain composition. The proper selection
and combination of the clays for best mechanical manij)u-
lation, proper drying and normal burning and vitrification
are the main points to be considered. In this respect it is
evident that much can be done if the drying and burning
behavior of each clay is thoroughlj^ understood. With a
mixture, for instance, of Georgia kaolin, North Carolina
kaolin, and Tennessee ball clay it would be possible to
meet practically every condition and by adjusting the
amount of the coarser grained materials, the drying and
burniuir behavior could be regulated sntisfactorilv. The

VlTRIflCATION RANGE AND DI-ELECTRIC BEHAVIOR. 43

practice of the white v^aia potter to depend upou three or
four materials for the introduction of his clay substance
is a wise one, provided a i>yo\)er balance is maintained
between clays of the ojjposite type.

What has been said regarding the di-electric beliavior
of porcelains at atmospheric temperatures does not. of
course, apply to more elevated temperatures. The eJectri-
cal resistance of porcelain rapidly decreases with increas-
ing temperature, and at the same tiine the composition
becomes a more and more important factor. Thus a high
feldspar porcelain ma^' be an excellent nonconductor at
ordinary temperature, but might break down utterly at a
temperature of several hundred degrees C.

Owing to the fact that graphic presentation has been
employed througliout, the facts found are moj-e clearly
shown by the diagrams than can be summarized in words.
The fact tliat feldspar is a solvent and does not react chem-
ically^ with the clay substance is again brought out clearly,
as well as the observation that this mineral begins this
dissolving action at a low temperature. It was shown
also that the structure and fineness of grain of the clays
incorporated in a body have a decided influence upon the
vitrification process. In one case (Tennessee ball clay)
tlie feldspar-flint mixture even behaved as a refractory con-
stituent in the 50% clay body. From this it follows that
the feldspar content required depends upon the individual
clays employed and not upon the total content of so-called
clay substance. In this way it may be possible to cut
down the percentage of feldspar by changing one or more
of the clays.

Attention was called to the fact that the rate of vitri-
fication of the various bodies was not (^onstant, but showed
an acceleration, usually between cones 4-7. This was
ascribed, in part, to the lower viscosity of the resulting
fusible component at these temperatures.

The English China clay showed a more uniform rate
of vitrification and a greater range than the two American
IvRolins.

44 VITRIFICATION RANGE AND Dl-ELECTRIC BEHAVIOR.

Vitrification is accompanied by increase in tlie speci-
fic volume. The worlv failed to show any regular relation
between feldspar content and burning temperature on the
one hand and the development of vesicular structure on
the other.

The electrical resistance seems to depend more upon
sound vitrification and good mechanical structure than
chemical composition, excepting, of course, insofar as the
latter governs the vitrifying behavior.

The thanks of the writers are due to Professor C. W.
Kolfe, Director of the Department of Ceramics, University
of Illinois, for having granted the funds necessary for this
work, and to Messrs. W. S. Williams, A. E. Williams, S. B.
Eadcliffe and K. K. Hursh for tlieir careful work and
faithful cooperation.

DISCUSSION.

Mr. Funly: I notice that you plot your results on
basis of chemical composition, rather than mineralogical
constitution. Are you more willing to base your deduc-
tion on chemical composition than on mineralogical con-
stitution? In other ■v\'ords, would it not iiave been more
logical procedure to have plotted your data with the min-
erals as variants rather than the oxides of which the
minerals are comprised?

Mr. Bleininger : The results are referred both to the
chemical composition (from the analyses) and to the per-
centage composition of the three constituents. No attempt
has been made to get at the mineral composition, i. e., con-
tent of clay substance, feldspar aad quartz in their theo-
retical relations.

Air. Fnrdji: In the first place, we do not know the
exact mineralogical constitution of the commercial kaolins
and feldspars. In the second place, such breaking down
of originally added mineral compound, as for instance,
kaolinite to form sillimanite will not take place in the vit-
rified portion at tlie same temperature nor at the same rate

i

VITRIFICATION RAXGE AXD DI-ELECTRIC BEHiVVIOR. 45

as they would if lieated alone, i. e., without admixture of
other minerals. The transition from the unstable AI0O3
2 SiOo to the stable ALO,; : SiOo occurs in porcelains much
earlier than it would in pure kaolinite.

Then again, the reversible transition from quartz to
tridimite varies in rate with variation in viscosity, etc.,
of the molten solution in which the free silica is dissolved.
In some porcelain mixtures I doubt if there is a complete
reversal from tridimite to quartz.

It is a fact, however, — and Professor Bleininger will
agree with me in this — that the only decided chemical al-
teration taking place in vitrifying porcelain is the break-
ing down of kaolinite to the more stable form — sillimanite.
While it is a fact also that this transformation or breaking
down takes place in a fusion at much lower temperature
than it otherwise would, the researches that ^[r. VN'atts
quoted last year demonstrated that it Avas a very sluggish
transformation. This means that in a vitrified porcelain,
sillimanite is formed so slowly that it does not progress
very far under the normal burning condition prevailing in
porcelain factories.

We may not be in position to speculate as to the exact
constitution of the vitrified porcelain, yet we do know as
much, if not more, about the constitution of it in this
condition than we possibly can of it in the unburned con-
dition.

Jfr. Bleimnger: I do not agree ^ith Professor Purdy
in all he says. In fact, I believe we are still fnr off from
knowing what takes place during vitrification and fusion
in systems involving at least three minerals, under condi-
tions far from equilibium and infiuenced by such factors
as difference in fineness of grain, rate of heating and cool-
ing, etc. Again there comes in the diificulty of determin-
ing the minerals composing the clay, feldspar and quartz,
with any degree of accuracy. Surely, the structure of such
clays as the North Carolina and Georgia kaolins is not
differentiated by the present methods of mineral analysis

46 VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

or mineral computation. That we have realized the differ-
ences caused by the uses of different cla^ys is shown by the
very aim of this work where we have combined the same
feldspar and quartz witli four different clays. I see lience
no objection to referring the results to percentage composi-
tion and chemical formulfe. The latter at least are based
upon positive facts, the chemical composition obtained by
analysis. As soon as we have methods available for min-
eral analysis of reasonable accuracy, which do not depend
upon an insufficient technique or theoretical calculation, 1
am sure they will be used.

Mr. Purdy : What I have in mind is this. If you
should make up the body by molecular formula based on
chemical analysis of the materials, introducing your K2O,
etc., from different sources, would you have tlie same re-
sults? In other words, would you base a consistent argu-
ment or expect constant result by blending wholly on basis
of chemical composition? Does not tlie sort of minerals
you use have very large effect?

Mr. Bleininr/er: I do not deny that the mineral
structure is of importance, but the finer the constituents
of a body are ground the less important does the initiaJ
mineral composition become. Thus recent work has shown
that a good porcelain bod}^ was obtained from a mixture
of pure silica, pure alumina and alkali. Given tine enough
grinding and long enough burning and the initial mineral
structure will be wiped out. However, in most of our
American bodies the initial structure persists — a fact
which is well realized. What I wish to bring out is the
fact that the usual calculated mineral composition and
that obtained by the rational analysis is inaccurate and
based upon conceptions which are not in accord with facts.
Why not then be content with the chemical composition as
given by analysis? As to the iinal mineral composition
of a body very little is known. We know for instance that
sillimanite is formed in porcelains at certain tempera-
tures, but to use the amount of this mineral present as a
criterion of the value of a body seems far fetched.

VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR. 47

Mr. Furdij : The point in question might be made by
taking this case. Suppose we have the potash introduced
through a viscous medium like feldspar, that is, viscous
in the molten state, or through the medium of mica, or
any other silicate which contains alkalies? We could get
different results, or we might get the same results, with
the same chemical composition. It dei^ends upon the vis-
cosity of the medium through which the oxides are added
whether the reaction is going to come to equilibrium or
not, and the mineralogical constitution, both initial and
final, is in my estimation much more important than the
simple analysis of tlie body. Wo have tried some of those
tilings this year and found that it was far more logical, or
oui- data were followed far more easily on the simple min-
eralogical basis, than on basis of chemical composition.
We have come to the conclusion, therefore, that it is fool-
ishness to write a molecular formula of the body as we do
of glazes, because we have produced different bodies on
the same formula.

If you mix potash, alumina, and silica in the same
proportion as in pure feldspar, and then frit the mix,
you will obtain feldspar. No one questions that. Day and
Allen did that very thing, but they had to fuse and refuse
the mass many times before they obtained any large per-
centage amount of feldspar from the mix used. If a feld-
spar be thus made and used as a constituent in porcelain,
may I ask would it not be feldspar still, although syn-
thetically prepared? Watts imitated Cornwall stone thus,
but he calcined his synthetic mix before attempting its
use. You cannot add KoO, ALOo and SiOo as such and
make a porcelain that would be like one of same composi-
tion but made from commercial feldspar, etc.

Tlie researches of Seger, Mellor. Simonis. Berdel,
and of Shepherd and Ilankin, leave but little if any doubt
that fusion in porcelain is not attended by chemical reac-
tion between the mineral components, and that the only
chemical phenomena noted is the formation of sillimanite
from kaolinite.

48 VITRIFICATION RANGE AND DI-ELECTRIC BEHAVIOR.

Mr. BJeiniuger: It will be noticed that the results of
the work, porosity and di-electric strength, are not re-
ferred to the chemical composition but to the percentages
of clay, feldspar and quartz. The chemical composition
has been used for the purpose of classification for which
purpose I maintain that it is closer to the facts than any
hypothetical mineral composition.

3Ir. Purely: There is one other point in that connec-
tion. Of course, in the bodies we do not completely fuse
the mix. Such a procedure would result in distorted ware.
Synthetically made porcelain, unless made from fritted or
calcined material, will not be of the same sort as those
porcelains you ha^s^e exhibited here, i have seen porcelain
glazes attempted synthetically. They were failures. The
same would be true in porcelain bodies. While working
in a floor tile factory, I attempted the duplication of cer-
tain French porcelain on basis of chemical com])osition.
I failed. The same can be said for any ceramic body and
nearly all of the alkaline earth glazes.

But there is one other point, feldspar in large quan-
tities produces a vesicular structure. Have you deter-
mined the effect of bleb structure in di-eleetric strength?
I noticed the high strength was in the high feldspar bodies
but the maximum feldspar was only 50%.

Mr. Bleininger: The determinations of the true spe-
cific gravities Avere made for the primary purpose of get-
ting at the "bleb" structure, but we were grievously dis-
appointed in finding that the porosity curves expressing
the enclosed pore space were far from consistent. Roughly,
the bleb space increased with the content of feldspar, but
it seemed that the variations in physical structure were an
important factor. Thus the amount of water used and the
manipulation evidently brought about fluctuations in the
volume of enclosed poral space. We regret exceedingly
that we failed to show any consistent relation in this
direction.

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