mum values of Mo (eq 29) assuming minimum andmaximum values for both Rmax and e. The range of* may be taken as 0.7 to 0.9. Compute the cor-responding values for fx Mo and mark out the verticalband corresponding to these limits in figure 1.

5. For the maximum and minimum limits assumedfor both L and e, compute the corresponding limitsfor Lo (eq 28). Compute the corresponding valuesof QL0/Ap and mark out the horizontal band cor-responding to these limits in figure 1. Steps (4) and(5) result in a design rectangle on figure 1 withinwhich a solution is possible.

6. Further limit this design rectangle by excludingregions of figure 1 representing greater and lesserarea A (really /JLA) than desired.

7. For gas flow, compute the maximum tolerablevalue of the coefficient of the Knudsen term b andthe corresponding minimum value of fiber diameterd. Exclude regions of figure 1 representing smallervalues of d (really d/fi). One may then choosedesign parameters corresponding to any point inthe design region that has not been excluded.

8. When the flowmeter is built and tested, adjust-ment of the resistivity can then be made by theprincipal technique^of changing the weight of glasswool used.

Financial support for this investigation was pro-vided by the Office of Naval Research under a proj-ect on Basic Instrumentation of Scientific Research.Grateful acknowledgement is also due W. A. Wild-hack, at whose suggestion and under whose super-vision the development of the glass wool flowmeterwas carried on.

V. References

[1] National Bureau of Standards Report to the Bureau ofAeronautics, Navy Department, Washington, D. C ,entitled, Linear pressure drop flowmeters for oxygenregulator test stands, reference 6.2/6211-2885 (Sept. 25,1947).

[2] P. C. Carman, Trans. Institution Chem. Engrs. 15, 151(1937); 16, 168 (1938).

[3] P. C. Carman, J. Soc. Chem. Ind. 57, 225 (1938); 58,1 (1939).

[4] E. Wiggin, W. Campbell, O. Maass, Can. J. Research 17,318 (1939).

[5] J. Fowler and K. Hertel, J. App. Phys. 12, 503 (1941).[6] R. Sullivan, J. App. Phys. 12, 503 (1941); 13, 725 (1942).[7] O. Emersleben, Physik. Z. 26, 601 (1925).[8] R. Tolman, Statistical mechanics with applications to

physics and chemistry (Chemical Catalogue Co., NewYork, N. Y., 1927).

WASHINGTON, April 6, 1950.

Journal of Research of the National Bureau of Standards Vol. 45, No. 5, November 1950 Research Paper 2151

Density, Refractive Index, Boiling Point, and VaporPressure of Eight Monoolefin (1-Alkene), Six Pentadiene,

and Two Cyclomonoolefin Hydrocarbons1

By Alphonse F. Forziati,2 David L. Camin,! and Frederick D. Rossini3

Density (at 20°, 25°, and 30° C), refractive index (at seven wavelengths at 20°, 25°,and 30° C), vapor pressure, and boiling point (from 48 to 778 mm Eg) of 16 highly purifiedsamples of hydrocarbons of the AIM NBS series were measured for S monoolefin (1-alkene),(> pentadiene, and 2 cyclomonoolefin hydrocarbons.

The data on refractive index were adjusted by means of modified Cauchy and Hart-mann equations, and values of the constants are given for each compound.

The data on vapor pressure were adjusted by means of the method of least squaresand the three-constant Antoine equation. The values of the constants are given for eachcompound.

Values were calculated for the specfic dispersions, (nF—nc)ld and {nK — nn)l<i.

As a cooperative investigation of the Nat ionalBureau of S t a n d a r d s , the I1. S. Office of RubberReserve, and the American Petroleum [nstituteResearch Project (>, measurements of density, re-fractive index, vapor pressure, and boiling point,were made on highly purified samples of ei<j:htnionoolclin (1-alkene), six pentadiene, and twocyclomonoolelin hydrocarbons of the API NBSseries.

The compounds measured were made available'This investigation was performed at the National Bureau "f Standards :is

part of the work of the American Petroleum [nstitute Research Project 6 on the"Analysis, purification, and properties <>i hydrocarbons."

Formerly Research Associate on the American Petroleum [nstitute ResearchProject <'..

1 Present address: Carnegie [nstitute of Technology, Pittsburgh 13, Pa.

through (lie American Petroleum Ins t i tu te ResearchProject 11 on the "Collection, calculat ion, andcompilat ion of data on the properties of hydrocar -bons . " T h e samples were purified by the AmericanPetroleum Ins t i tu te Research Project 6 on the"Analysis , purification, and properties of hydro-carbons," Iron) material supplied by the followinglaboratories:

L-Pentene, by the Phillips Petroleum Co., Bartles-ville, Okla.

l-IIexene, l -heptene, l-noneiie, L-undecene, and1,4-penfadiene, by the American Petroleum Ins t i tu teResearch Project 45, at the Ohio S ta le University,(Jolumbus, Ohio.

406

1-Octene, 1-decene, 1-dodecene, 2-methyl-l,3-butadiene, and cyclohexene, by the AmericanPetroleum Institute Research Project 6.

1,2-Pcntadiene and 2,3-pentadiene, by the Hydro-carbon Laboratory, Pennsylvania State College,State College, Pa.

1 ,cis-3-Pentadiene and l,£rcms-3-pentadiene, bythe Office of Rubber Reserve, Washington, D. C.

Cyclopentene, by the Atlantic Refining Co.,Philadelphia, Pa., and the American PetroleumInstitute Research Project 45 at the Ohio StateUniversity, Columbus, Ohio.

The purification and determination of purity andfreezing point of these compounds are described inreferences [1 to 5].4

It is believed that in each case the impurity was ofsuch nature and present in such small amount thatthe properties measured were not affected beyondthe indicated limits of uncertainty.

The measurements of density were made at 20°,25°, and 30° C with a density balance, the assembly,calibration, and operation of which has been previ-ously described [6]. The experimental results ondensity are given in table 1. Individual measure-ments were reproducible within ±0.00003 g/ml.The accuracy of the tabulated values, including theeffect of impurities, is estimated to be ±0.00005 to±0.00010 g/ml for the 10 monoolefins and ±0.00008to ±0.00015 g/ml for the 6 pentadienes.

The refractive index was measured by means of thesame apparatus and procedure previously described[7]. The calculations and correlations were also madein the same manner as in [7]. Table 2 gives thevalues of the constants of the modified Cauchy andHartmann equations for each of the 16 compounds.The fifth and last columns of the table give the root-mean-square value of the deviations of the observedfrom the calculated points. Table 3 gives theadjusted values of refractive index at each of sevenwavelengths (from 6,678 to 4,358 Angstrom units) at20°, 25°, and 30° C. Figure 1 is a plot of the valuesof the constants nm and Cof the modified Hartmannequation, as a function of the number of carbonatoms in the normal alky] radical of the series ofL-alkenes. Table 4 gives the values of the specificdispersions \(){(nF—nc)/d and L04(ng—nD)/d calcu-lated from the values of refractive index in table 3and of density in table 1.

TABLE 1. Values of density

Compound

1-Pentene1-Hexene,1-Heptene1-Octene .1-Nonene1-Decene1-Undecene _..1-Dodecene

1,2-Pentadiene1 ,czs-3-Pentadienel,<rans-3-Pentadiene._1,4"Pentadiene2,3-Pentadiene -2-Methyl-l ,3-butadiene

Cyclopentene . .Cyclohexene

Formula

C5Hio--_CtH.it--.C7H14C 8Hi6- . .CgHis

CnH22C12H24

C 5 H 8 - -C5H8C5H8--C5H8C5H8 -C5H8

C 5 H s - -C0H10

20° C

g/ml0.64050

. 67317

. 69698

.71492

. 72922

. 74081

. 75032

.75836

. 69257

. 69102

.67603

.66076

. 69502

. 68095

.77199

.81096

Density *

25° C

g/ml0.63533

.66848

.69267

.71085

. 72531

.73693

.74655

. 75474

. 68760

. 68592

. 67102

. 69000

. 67587

. 76653

.80609

30° C

g/ml

0.66374.68815. 70658. 72134. 73304. 74276. 75103

.68260

. 68082

.66592

.68479

.67076

.76124

.80141

Temper-aturecoeffi-

cient ofdensityat 25° C

g/ml ° Cb 0.001034

. 000943

. 000883

. 000834

. 000788

.000777

.000756

.000733

.000997

. 001020

.001011

. 001023

. 001019

. 001075

. 000955

For air-saturated hydrocarbon in the liquid state at 1 atm.This value at 22.5° C.

1.42

3 4 5 6 7 8 9NUMBER OF CARBON ATOMS

IN THE NORMAL ALKYL RADICAL

FIGURE t. \ralues of the constants, n^ and C, of the modifiedHartmann equation, as a function of the number of carbonatoms in the normal alkyl radical for the series of t-alkenes.

1 F i g u r e s In b r a c k e t s In d ica te i he l iteral ure re ferences ai i he e n d of i h is p a p e r .

407

TABLE 2. Tralues of the constants of the modified Cauchy and Hartman equations

Compound

1-Pentene._1-Hexene1-Heptene1-Octene_ _1-Nonene1-Decene1-Undecene1-Dodecene

1,2-pentadienel,ris-3-Pentadiene _l-trans-3- Pentadiene1,4-Pentadiene-.2,3-Pentadiene2-Methyl-l,3-butadiene

C yclopenteneCyclohexene

Formula

C5H10-C9Hi2C - H HCsHie. .C9H18C10H20C11H02C12H24

C5H8C5H8--C5H8

C5H8C5Hs._

C5H8

C6Hio

Constants in the equation »An=a+6/X2

aXlO 3

2.9982.7732.5602.4082.3092.2442.1762.121

3.0533.2183.192

3.1943.225

2.9722.672

6X10 8

0. 0471.0308.0382.0334.0284.0285.0295.0292

.0433

. 0737

.0690

.0462

.0694

.0293

.0326

PXIC

7.444.303.186.475.764.104.433.96

5.924.243.42

5.198.02

2.002.03

Constants in the equation n\ =

71 00

1.356001. 372411.384741.393111.400481.406161.410811.41490

1.401191.410101. 40386

bl. 374041.407281. 39722

1.405501.42947

C

0. 003924. 004022.003835.004271. 004103. 004169. 004185.004111

. 004885

. 006167

. 006289b. 004320

. 005353

. 005967

. 004350

. 004429

»oo + C/(X-X*) i-s at 25° C

X*

0.10090.09976.10874.09260.09942. 09725.09737. 10033

. 12273

. 14772

.14256b . 12451

. 11758

. 13783

. 10549

.10859

PX10 5

4.113 251.605.071 652.542.071.14

5.312.103.74

b4. 471.735.54

1.031.57

b These values at 20° C.

TABLE 3. Values of refractive index at seven wavelengths and three temperatures

Wave-length

6678.16562. 85892. 65460. 75015.74861.34358.3

(1678. 165fi2. 85892. (i5460. 75015.74861.34358. 3

6678. l6662. 85892, 65460. 75015.74861.3

4358. 3

6678. I6562. 85892. <i5460. 75015.7

1861.:!1358. 3

Spectralline

HCred-H c . .

HeNaoIk-,II ,,HvHg«

Hered11.N . i i )

l ln. .lie,,, ,I IKMl!.

, , 1

HeN : i nI If-',HeiH F

Index of refraction at—

20° C 25° C 30° C

1-Pentene, C5H1

1. 368*31.369161.371481.373481.37614I. 377251.38183

1.365731. 366051.368351.370321.372951.374051.37858

1-Nonene,

1.412981.413321.415721.41778[.420521.42167L. 42639

1.410(111.410951.41333L. 41 5381.418101.41924L. 42393

1.408241.408581.410941.412981.416681.4168]1.42147

1,2-I'entadienc, C6H8

1.11721.11769.42(191. 12372.42760.42910. 43579

1.414091.414541.417731.42052I.42128L. 42586L. 43251

1 . 4 1 0 9 4I. 111:!1.)1.41456L. 417321.421061.422621.42923

2,3 IVnhidiciic, < \-. 11 K

1.424601.42498I. 12842L. 431401.436421.437111. I l l l : .

. 1 2 1 2 0

,42168.•12509. 12805. 13204. 43372,44071

1.417901.418381.42176I. 121701. 42866L. 43033L. 43727

20° C 25° C 30° C

1-Hexene, C6H12

1.385191.385521.387881.389911.392611. 393731.39837

1.382351.382681.385021.387031.389711.390831.39543

1.379511.379841.382161.384151.386811.387931.39249

1-Decenc, C10H20

1.418701.419041.421461. 423521.42627L. 427411.43213

1.41639L. 416731.41913L. 421181.4239]1.425051.42974

41408414424168041884421551226(142735

l,ds-3-Pentadiene, C5H8

,43103.43168. 43634. 44046.44612. 44864

1.45887

L. 427651.428291.4329]1. 13699L. 4426]1.4450]L. 46526

1.424271.424901.42948L. 43352L. 439101.441481.45166

2-Methyl-l,3-l>utndi(>ne,

L. 417081.417681.42194L. 425701.4308]1.433001. 4422]

1.413701.41429L. 418521.422241.42731I. 129481.43862

1.41032I. H0901.415101.418781.4238]L. 42596I. 43503

20° C 25° C 30° C

1-Heptene, C ? H H

1.397111.397441.399801.401831.404551.405691.41042

1.394461.394791.397131.399141.401841.402971.40766

1.391811.392141.394461.396451.399131.400251.40490

1-Undecene, C11H22

1.42332L. 42366L. 42609L. 42816I. 130931.432081.43682

1.421081.421421.423831. 42589L. 42864L. 429781.43449

4188411918•1215742362126351271843216

1, «rans-3-Pentadien<\ ("siIs

1.42483.12517.43008.13115. 43972.11209.45219

1.42148L. 422121.426691.43073

I. -136251.4386]I. 44863

1.418131.418771.423301. 127311. 132781.43513L. 44507

( 'yc l ( i |MMilc i ic . ( ' . ' ,11K

L. 41947I. 11984I. 12216I. 12172L. 42773L. 42900L. 43423

L. 41643L. 416801.419401.-12165I. 12161L. 425901.43110

1.413391. 41376L. 41634L. 418581.42158L. 42280I. 12797

20° C 25° C 30° C

1-Octene, C8H1 6

1.405941.406291.408701.410771.413511.41465I. 11933

1.403461.403801.406201.40825L. 410971.412101.41675

1.400981.401311.403701.405731.408431.409551.41417

l-Dodecene,

1.427271.427611.430021.43210I.434861.4360]1.44077

1.425081.425421.427821. 129881.432621.433771.43850

1.422891.423231.425(12L. 427661.430381.431531.43623

1,4-Pentadiene, C5H8

1.38550L.3859]1.388761.391251.39161

t. 396031.40199

Cycloliext'iie, CnIIn,

L. 443441,443831.446541.448881.4520]1.453331.46877

1. illicitI. 111081.44377I. 446101.44921I 150521.45593

L. 437041.438331. 1IIOOL. 44332I. 146411. 11771I 15309

408

TABLE 4.

Tempera-ture

202530

202530

202530

2025 . .30

nc)fd

Calculated values of the specific dispersion

W*(ng-nD)/d

1-Pentene

126.31125. 92

161.59161.02

1-Nonene

114. 51114.30114.09

146.32146.14145.98

1,2-Pentadiene

164. 75164.63164. 52

214.85214.95215.06

2,3-Pentadiene

174.53174. 49174.51

226.32226. 38226. 49

10*(nF-nc)/d riD)/d

1-Hexene

121 96121.92121.89

155.83155.73155.63

1-Decene

112.98112.90112.82

144.03143.98143.92

Pentadiene

243.99243.76243. 53

326.04325.84325.64

2-Methyl-l,3-butadiene

224.98224. 75224. 52

297.67297.39297.13

nc)Jd10*(nt-no)/d

1-Heptene

118.37118.09117.85

152 37152.02151.71

1-Undecene

112.22111.98111.75

143.01142. 79142.58

l,trans-3-Ptmtadiene

245.85245. 75245. 68

327.06326. 96326. 92

Cyclopenteno

118.65118.72118.75

152.46152. 64152. 78

10*(nF-nc)ld

10*(ng-7lD)/d

1-Octene

116.94116.76116.62

148. 69148.41148.18

1-Dodecene

110.77110.63110.51

141.75141.51141.27

1,4-Pentadiene

153.18 200.25

Cyclohexene

117.15117.11117.04

150.81150.85150.86

The measurements and calculations of vapopressures and boiling points were made as previouslydescribed [8, 9], except that the samples were intro-duced into the apparatus without contact with air.Table 5 gives the experimental data on the tempera-tures and pressures of the liquid-vapor equilibriumfor the 16 compounds. Table 6 gives the values ofthe three constants of the Antoine equation, thenormal boiling point at 760 mm Hg, the pressurecoefficient of the boiling point at 760 mm Hg, andthe range of measurement, in pressure and in temp-erature. The last column of table 6 gives (lie root-mean-square value of the ratios of the deviations ofthe observed points from the Antoine equation to

the expected standard deviation [9]. Figure 2 isa plot of the values of the constants B and C ofthe Antoine equation, as a function of the number ofcarbon atoms in the normal alkyl radical of the seriesof 1-alkenes.

c.\J\J\J i

1800

1600

1400

1200

' 1

-

-

-

o

OOO O i

1

•

o

1

1

•

o

1

1

•

o

1

1

o

•

1

1

o

•

1

-

<

-

-

230

- 220

- 210

- 200

- 190

180

3 4 5 6 7 8 9 10

NUMBER OF CARBON ATOMSIN THE NORMAL ALKYL RADICAL

FICTJRE 2. Values of the constants, B and C, of the Antoineequation, as a function of the number of carbon atoms in thenormal alkyl radical for the series of 1-alkenes.

O=B;%=C.

t P

1-Pentene

°C30. 72:',30.28929. 79629. 362

28. 900

24 584IS. 4 OK12. 834

in in 11 g779. 98768. 46755. 52744.27732. 40

62S 21501.02402. HI

TABLE 5.

t P

L-Hexene

°C64.31163. 83763. 29962. S2762.323

50.91444.76338.99333.399

28. 76223. 72019.95015. S90

in m 11 f780, 0376S. 49755. 54744. 29732, 12

501.03102. 82325. 27262.04

217.44176, L5119.81121 s:,

Experimental data on the

t P

l-Heptene

°C94.53191.02293.44492.94]92.391

SI). 17973. 56367. 366

56, 38450.97046, 92342. 56438. 281

34, 525

28 76S25, 49221.609

nun Ilj;780.0876S. 53755. 56714.31732. 4 1

501.05402. 82325. 27

217.43176 13119 60124.84103.85

87 Ul

67 115" 69i ; 89

t

temperatures and pressures of the

P

1-Octene

°C122.223121.685121.075120.5391 19.967

106.997

03.42887 053

SI 77976 02271 73667 09662 557

58 55755 58]52 410IS 975II 893

mm I IK780. 217(is. 62755. 64744.38732. 50

501.09

325. 27262 03

217 44176 13149 60124 SIL03 84

87 9177 IS67 1657 8847. 87

t P

1-Nonene

°C147.860147.2X9146.6531 16.091

L45.488

L39 859131.881124.521117 6221 III 935

'I!) 34194 S2989 942S.r> 202

SI 00177 S6I71 51770 87486. 607

III III 1 1!'

7so. 2276s. 82755. 63744.38732. 50

62S 33501.09402. si325. 26262. 03

176 131 I'.I 611124. SI103 85

S7 9277 4967 4657. 6947.89

t

liquid-vapor equilibrium

P

L-Decene

°C171.605171.012170.345169.762169. 131

154.939117. 265III) 063

127.265120 9951 16 283I I I . 213106 223

101 S l l98 60495 13491.30886, 77 1

mm Bg780. 2676S. 65755. 67744.42732. 53

501.12102. 86

325. 22

217.41176. 14149.84124. HliL03.87

87 9377.5167 IS57.7147.98

t P

1-Undecene

°C193.712193.130192.441191. S32191.179

1S5. 091176. 162168.501161.031153.780

117.780141.2111136.350131. (LSI125.902

121.355117.9971 L4.3881111.423105. S6C,

m in 11 g7so. 26768. 66755.69744.43732. 55

628. 38501. 13102. S7325. 2S262.05

217.45176. 11149.65124.86103.87

87.9477.5167. 4857 7247.99

t P

1-Dodecene

°C214.472213. S26213. 125212.497211.823

205. 542196.621188.406ISO. 699173.211

167.019160.266155.208149.773144.428

139. 736136.258

128.424123.703

mm Hi'780.36768. 75755. SI744.57732.62

62S. 45501, 21102. 97325. II262. 1 1

217.54176.24149.72121.95103.97

SS.0377. 59

57. 7848.02

409

TABLE 5. Experimental data on the temperatures and pressures of the liquid-vapor equilibrium—Continued

1,2-Pentadiene

°C45.63145.19144.69044. 25243. 778

39.37333.12627.37421.97116. 702

12.361

mm Hg780. 27768. 66755. 71744.47732. 52

628.37501.13402. 89325.32262.08

217.48

l,ds-3-Pentadiene

°C44. 84644.40343.90243. 46142.989

38. 57832.32626. 56621.16115.917

mm Hg780. 28768. 68755.73744. 49732. 54

628.39501.15402.91325.35262.10

l,<roM*-3-Pentadiene

°C42.81042.36741.86641.42340. 952

36. 53830. 28224.51419.109

mm Hg780. 28768. 67755.72744. 48732.53

628.39501.15402. 90325.34

1,4-Pentadiene

°C26. 71426. 28725. 80625.38424.931

20.69914. 706

mm Hg780. 26768. 66755. 70744.46732. 51

628. 36501.12

2,3-Pentadiene

°C49.04148.60248.10147. 65847.183

42.78136. 54130. 80325.402

mm Hg780. 26768.66755. 70744.46732.51

628.36501.12402.88325.31

2-Methyl-l,3-bu-tadiene

°C34.83434.39933.90333. 46933.006

28. 66122. 50616.836

mm Hg780. 29768.69755. 74744. 51732.55

628.40501.16402.92

Cyclopentene

°C45.02444. 57644. 07143. 62443.146

38. 67832.34026. 50621.02815. 718

11.325

mm Hg780.13768. 58755. 64744. 41732.46

628. 25501.09402. 86325.34262.07

217.47

Cyclohexene

°C83. 85283.35382. 79182. 29281. 757

76. 76669. 70863. 20057.10751.191

46.30240.97636. 99632. 70228. 490

24. 79422.06319.13715.92012.236

mm Hg780.14768. 59755. 66744.42732.47

628.26501.10402.87325.35262. 07

217.48176.20149. 70124.89103.94

88.0177.5967.5557.8248.13

T A B L E 6. Summary of the results of the correlation of the experimental data with the Antoine equation for vapor pressure

Compound

1-Pentene1 llcxene .1-Heptene1-Octene1-Nonenel -I )ecenei -Undecene1 •Dodccenc

1,2-Pentad ienel,ci$-3-Pentadiene

1,4-Pentadiene2,3-Pentadiene2-Methyl-l,3-butadiene

Cyclopentene .Cyclohexene

Formula

C5H10 -

C7ITnCgHio

C11H22C12H24

caisC5H8

('il'sC5H8.._

CjHg. . .C0H10

Constants of the Antoine equa-tion logi0P=/l-fl/(C-N), or«=/?/(^4-log10P)-C (P in mmHg; t in °C)

A

6.785686.865736.900696. 932626. 953896. 900366.96662C>. 97522

7. 010996.941796. 922576. 818806.886036.90335

6. 920666.88617

B

1014.2941152.9711257. 5051353. 4861435.3591501.872L 562.4691619.862

1154.4201118.3711108.9371025. 016L086.636L080.996

1121.8181229.973

C

229.783225. 849219.179212. 764205. 535197 578189. 743182. 271

234. 652231 327232. 338232. 354223. 040234.668

233. 446224. 104

Normalboiling

point at760 mm

Hg

°C29. 96863. 48593. (143

121.280146.868170. 570192.671213. 357

44.85644. 06842. 03225. 0(1748. 26534.067

44. 24282. 979

Pressurecoefficientdt/dPat

760 mm Hg

"C/mmBg0.03801

. 04149

. 04447

.04711

. 04944

.05157

. 05348

.05522

. 03867

.03875

.0387'.!

.03720

.03871

.03818

.03928

. 04381

Range of measurement

Pressure

OTWlHg402 to 780124 to 78048 to 78048 to 78048 to 78048 to 78048 to 78048 to 780

217 to 780262 to 780325 to 780f.Ol lei 780325 t o 780402 to 780

217 to 78048 to 780

Temperature

°C12. 8 to 30.715.9 to 64.321. 6 to 94. 544.8 to 122.266.6 to 147.986.7 to 171.6

105. 8 to 193.7123. 7 to 214.4

12. 3 to 45.615. 9 to 44.819.1 to 42. 814. 7 to 26.725. 4 t o lit. (I16. 8 to 34.8

LI. 3 to 15.0L2. 2 to 83.9

Meas-ure ofpre-

cision

p0.63

.96

.62

.78

.971.61. 55.49

.76

. L6

.22

. 12

.49

. 20

. 46

.54

[1] A. It. Glasgow, Jr., E. T. Murphy, C. B. Willingham, andF. I). Rossini, J. Research NBS 37, 141 (1946) KP1734.

[2] A. J. Streiff, E. T. Murphy, V. A. Sedlak, C. B. Willing-ham, and F. I). Rossini, j . Research NBS 37, 331 (1946)R I' 1752.

[3] A. J. Streiff, E. T. Murphy , J. C. Cahil l , II. V. F lanagan,V. A. Sedlak, C. B. Wi l l ingham, and F. I). Ross in i ,J . R e s e a r c h N B S 3 8 , 53 (1947) R P 1 7 6 0 .

HI A. .1. Streiff, E. T. Murphy , J. ('. Z i m m e r m a n , L. F.Son ic , V. A. Sedlak, ('. B. Wi l l ingham, a n d F. 1). R o s -sini , .I. Research N B S 3 9 , 3 2 ] (l'.H7) R P 1 8 3 3 .

[5] A

[6] A

[7] A

[8] C

[9] A

. J. Streiff, J. C. Zimmerman, L. F. Soule, M. T. Butt,V. A. Sedlak, C. B. Willingham, and F. 1). Rossini,./. Research NBS 41, :vi:\ (1948) RP1929

F. Forziati, B. .). Mair, and F. D. Rossini, J. R(NBS 35, 513 (1945) RP1685I

•arch

F. Forziati, J. Research NBS 44, 373 (1950) RP2085.B. Willingham, W. J. Taylor, J. M. Pignocco, and V.

1). Rossini, J. Research NBS 35, 219 (1945) RP1670.F. Forziati, W. R. Norris, and F. D. Rossini,.!. Research

^ B S 43, 555 (1949) RP2049.

WASHINGTON JULY 3, L950.

410