November 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
to 172' C. The combined material boiling over 172' C. was treated with a solution of sodium ethoxide in alcohol until alkaline to remove residual chlorine. After the chlorine-free material had been stripped under reduced pressure, careful fractionation a t atmospheric pressure gave 556 grams (2.73 moles) of p-methylvinyltriethoxysilane (boiling point 177-9" C., d25 0.90), a yield of 80 mole %. CROTYLTRICHLOROSILAXE. 111 a 1-liter three-necked flask equipped with reflux condenser, mechanical stirrer, and dropping funnel there was placed 379 grams (2.0 moles) of crotyltrichlorosilane. Through the dropping funnel there was added 184 grams (4.0 moles) of anhydrous ethyl alcohol at room temperature over the course of 1 hour. Hydrogen chloride evolved was allowed to escape into a fume hood. -4t this point the reaction mixture was heated to reflux and 92 grams (2.0 moles) of ethyl alcohol were added during a period of 2 hours. After unreacted material had been removed and residual chlorine neutralized with sodium ethoxide, the crude product was stripped under reduced pressure. Fractionation of the stripped material a t atmospheric pressure gave 328.5 grams (1.51 moles) of crotyltriethoxysilane (boiling point 193-195' C., d26 0.89, a yield of 75.5 mole %). Analysis. Calculated for CloHzzSiOa;C, 55.1; H, 9.9, Si, 12.9; unsaturation, 0.735 gram of bromine per gram. Found: C, 54.9; H, 10.2; Si, 12 65. unsaturation, 0.96 gram of bromine per gram. CHLORINATION
I n a glass reaction vessel equipped ALLYLTRICHLOROSILANE. with a gas inlet tube and side arm there was placed 229 grams (1.3 moles) of allyltrichlorosilane. The vessel was placed in an ice bath and chlorine was slowly bubbled into the chlorosilane for 5 hours. During this time a total of 110 grams of chlorine xas added. Distillation of the reaction product gave 186 grams of impure material [boiling point 53" C. (0.3 mm.)], uThich upon careful fractionation yielded p,r-dichloropropyltrichlorosilane [boiling point 36" C. (0.15 mm.), d261.471, Analysis. Calculated for CaH5CljSi: Si, 11.3; C1, 72.0; C, 14.6; H, 2.04. Found: Si, 11.2; C1, 73.0; C, 14.4; H, 2.2. I n a glass reaction vessel p-METHYLVINYLTRICHLOROSILANE. equipped with a gas inlet tube and side arm there was placed 253 grams (1.44 moles) of 0-methylvinyltrichlorosilane. Chlorine was passed into the compound for 3 hours, during which time the reaction mixture became hot and 109 grams of chlorine was abbarbed by the sample. Some substitution of chlorine also took place, as indicated by evolution of hydrogen chloride during the reaction. Distillation of the reaction mixture (362 grams) gave 242.5 grams of material [boiling point 87-91' C. (20 mm.), d25 1.46, per cent hydrolyzable chlorine 57.7 (theory for four chlorine atoms 57.6)], which upon careful fractionation gave 139 grams (0.56 mole) of reasonably good c&dichloropropyltrichlorosilane [boiling point 84.5-86.5' C. (17 mm.), d251.453. I n a glass reaction vessel of 500CROTYLTRICHLOROSILANE. mi. capacity equipped n i t h a side arm and gas inlet tube there was placed 189.5 grams (1 0 mole) of crotyltrichlorosilane. A cold trap mas connected to the side arm to protect the reaction vessel from moisture. After the vessel had been immersed in a mixture of dry ice and acetono to prevent substitution, chlorine was passed in for 46 minutes. during which time chlorine addition no longer occurred. The gain in weight of the reaction mixture a-as 72 grams. Fractionation of the 259.5 grams of material
2367
collected gave 122 grams (0.47 mole) of 2,3-dichlorobutyltrichlorosilane [boiling point 76-77' C. ( 5 mm.), d2* 1.41, per cent hydrolyzable chlorine 57.3 (theory for four chlorine atoms 54.5)], and 127 grams of other unidentified products. DISPROPORTIONATION
ALLYLTRIETHOXYSILANE. I n a 250-ml. flask connected to a fractionating column there were placed 137 grams (0.67 mole) of allyltriethoxysilane and 1.2 grams of sodium ethoxide. The mixture was heated a t the reflux temperature for 5 hours, during which time 52 grams of material distilling below 165" C. was removed from the head of the column. Fractionation of this low-boiling material and the residual material separately gave 63 grams (0.20 mole) of ethyl silicate (boiling point 162-164' C., d25 0.92), and a complex mixture of products believed to be allylethoxysilanes. Formation of ethyl silicate in the reaction indicated that disproportionation of allyl and ethoxy groups had taken place. I n a 250-ml. flask connected to a CROTYLTRIETHOXYSILANE. fractionating column there were placed 134.5 grams (0.62 mole) of crotyltriethoxysilane and 2.0 grams of sodium ethoxide. The mixture was heated a t the reflux temperature for 20 hours, during which time 46.0 grams of material distilling below 175" C. \$as removed from the head of the column. At this point the residual material was stripped under reduced pressure. A total of 126 grams of volatile product was obtained. Fractionation of this material gave 42 grams (0.20 mole) of ethyl silicate (boiling point 162-165' C., d26 0.92), 45 grams (0.21 mole) of recovered crotyltriethoxysilane and 21 grams (0.092 mole) of dicrotyldiethoxysilane (boiling point 217-221" C., dZ60.87). Analysis. Calculated for CIZH2&3i02: C, 63.25; H, 10.5; Si. 12.3; unsaturation, 1.40 grams of bromine per gram. Found: C, 63.2; H, 10.8; Si, 11.4; unsaturation, 1.81 grams of bromine per gram. ACKNOWLEDGMENT
The authors wish to thank W. N. Moore, C. M. Birdsall, and others of this laboratory for many of the analyses and infrared data reported here. LITERATURE CITED (1) Bailey, D. L., Ph.D. thesis, Pennsylvania State College, 1949 (2) Hurd, D. T., and Roedel, G. F., IKD.ENG.CHEM.,40, 2078 (1948). 68, 1083 (1946). (3) Sommer, L. H., and associates, J . Am. Chem. SOC., (4) Sommer, L. H., Tyler, L. J., and Whitmore, F. C. Ibid., 70, 2872 (1948).
( 5 ) Sommer, L. H , Van Strien, R. E., and Whitmore, F C., Ibtd., 71 .~ 3056 ~~-~ (1949). (6) Swiss, J., and Amtzen, C. E. (to Westinghouse Electric Corp.), U. S. Patent 2,595,728 (Xay 6, 1952). (7) Wagner, G. H., and associates, ISD. EKG.CHEY.,45, 367 (L953). I
~~
~
I
RECEIVED for review March 24, 1954. ACCEPTED August 3, 1954. Presented before the Division of Organic Chemistry, Symposium on CarbonFunctional Silicones, at the 125th hfeeting of the AMERICANCHEMICAL SOCIETY, Kansas City, hlo.
Vapor Pressures of Silicon Compounds ARTHUR C. JENKINS AND GEORGE F. CHAMBERS Linde Air Products Co., Division of LTnion Carbide and Carbon Corp., Tonawcenda, V. Y .
V
APOR pressures of 20 silicon compounds were measured for use in plant design calculations. The range of pressure varies within 20 and 760 mm. of mercury. The constants of the Antoine equation logic Pmm. = A - B/(t C) are given for each compound. Vapor pressures of eome of these compounds have been reported by other workers, and in most cases the agreement with their data is satisfactory. The compounds used in this work were fractionated a t least twice in a column with 20 theoretical plates, and the center cut with a sharply defined boiling point was retained for the vapor
+
pressure measurements. An additional indiestion that the samples were of high purity was provided by the isoteniscope method, which involves repeated boiling of the sample a t constant temperature until constant pressure is attained. X o difficulty was encountered in obtaining a constant pressure within 0.05 and 0.10 mm. APPhR4TUS AXD METHOD
The vapor pressure apparatus was based on the Smith-Xenzies isoteniscope ( 6 , 8).
INDUSTRIAL AND ENGINEERING CHEMISTRY
2368
Vol. 46, No , I 1
TABLE I. E X P E R I J I J ~ Da~a ~ T A L01 SILICOS~ o v r ~ o v r u s .-
i,
l'mm.
C.
Obsd. Calcd.
:lllyltric lilorosilanc 43.7 53 0 j3.0 93 5 63 6 57 9 76.3 199.5 199.4 92 0 3 4 8 . 9 331 3 1 0 4 . 9 5 2 0 . 2 534 0 1 1 3 . 1 7 2 4 . 3 724.8 Diethyldic!ilorosilaiie 48.1 G5 3 83 7 100 0 116.5 127.7 6.0 21 3 31.1 35.5 43.6 ?$I :i 33 2 51 4 13 1
91 I14 147
159
40 4 83.9 176 2 305 9 511.7 706 2
40.4 85.7 174.5 306 0 511.6 705.4
50 0 51.7 1 0 3 . 9 114 0 I 5 5 4 137 0 167 5 187 2 274 3 27.5 5 315 6 315 J 363 1 362 7 482 .i 481 3 703 2 704 2
Histriclilorosilylethane 2 18 5 I8 6 i 48 2 48.9 1 134 2 I54 4 9 2 8 1 . 0 2R1 2
'
160 (1 223.5 3P29 489 G 6'10 1 630 1 40.7 7 5 5 5 735.0
; 483 3 9 3 74 0
Tetraclilorosilane 2 2 23 1 .34.2 40 G !G 5 .iG 9
l39.G 211.0 353 5 3 5 3 . 5 504 4 593 6 658 8 63G 5 7 9 8 . 0 708 1 l:Q 5 211 5
13 7 23 30 49 57 61
5 0
8 3 3
2.1 10 1 18.7 22 5 27 0 31.6
101 157 261 433 562 710
0 3 6 8 3 8
100 157 261 $37 566
8 3 8 3 0 711 5
1.2-DichloroetiiyItriclilososilane 102 2 61 2 61.2 128 0 1 3 8 . 1 157 0 147 3 245 3 203 7 1 4 8 . 4 303 4 303 8 1 6 4 . 0 480 4 182 2 180.5 738.0 7 3 8 . 5
101 7 108 8 153 8 175 6 194 8 197 4
37 4 37 5 60 8 70 0 147 1 147 3 281.8 281 7 462 6 4G2.6
236.8 333 4 466 0 342 R 638.9 750 7
237 3 333 2 468 6 541.6 649.0 75'2 ,5
Hcxaetliyloyclotrisiloxene 55.6 56 1 138 6 138 8 302.3 3 0 2 . 7 4 0 4 . 9 404 5 500 0 4 9 9 . 5 6 4 1 . 4 641 1
,
1!'2 1
861 218 2 340.2 431 0 531 0 731 .j
7 cliloi oailane I)icthyldiclilorosilane 7 UiirietliS-ldiclilorosilanc 7 I~ir~lien~ldiclilo:.osilan~6 Ethylilichlorosiiane 7 6
Ilexaetliylcyclotrisilosane ~Ie~iiyldichloiosilarie l\ietliyltrichlorosiianc Phenyltric!iiorosiianc Tetrachlorosihne Trichlorosilane Trimet tiylcnlorosilane \'iny!tl.ic;iloio4ilane \-inyltrierhoxy-silane
1116 -9922
183 251
93230 07712
116 8 202 0
115 0
..
2227 260 148? 223 14351 1328 24 1 158 1884 95480 61420 1664 276 58174 1102 I 9 9 7 18148 1.j3 0 1(Iq 7 lllcici 118!1 228
180 6 130. 4 13ij 4 70.5 70 3 301 4 304 0 7,j i 00' 3 98 8 160 9 .. 191.7
6 , 3 8 31 7 7 04812 6 87213 F 98140 6 97287 7.09110 6 95054 7.32284 7 . A4075
%XI.3 '40 9
1.276 I179 1167 1641
2.42 '26
1170 11!11 151.3 1733
235 230 220
11P
100
u n o 286
216
66 4 201 0 .57 3 31 0 57 6 $10 6 160 ,5
4'1' 9 66.4 201 0 .iO, 8 31.8
6.l 7
37 3
~Ieth~ltriclilo~~silane
161 3 186 6 213 0 223.9 232 3 242 8
210 7 235.6 260 2 281.2
863 230 0 340 7 481 7 531 0 752 2
",-Chloro~lrogyltriclilorosiianc 87.1 32 5 32 .i 121 8 126 4 126 8 14cj.3 308 0 3 0 7 . 6 139 1 4 0 0 . 2 4 0 9 . 1 1 7 1 . 6 j 7 5 . 8 576 2 1 7 9 . 4 70G 4 7 0 5 . 7
28 5 ,53 3 54 7 3s 7 88 2 88 2 . i 8 . 7 167 1 1 6 6 . 2 70 2 ci07.9 307 no 0 ,183.4 ,586 0 93 6 694 7 6 9 3 . 6
Dii~lienyldiclilorosilane
6 603!10 7 82031
225
Trichloroailnnc
Diiiiethyldiclilorosilane 27 8 38.0 48 0 38 0 66 1 72.1
I i 160 7
2: 2s 0 :I4 1
33 44 214 400 657 692
8 4 7 3 0 9
33 44 214 400 655 697
6 9 8 6
1 7
Trimethylchlorosilane
8G 7 2.6 2 7 . 0 252 3 38 7 397 8 43.0 464.1 4 8 . 5 561.2 55.6 7 1 1 . 9
86 7 253.9 397 2 463.8 561.7 711.4
64.3 21.2 21 1 81.0 46 2 46.5 90.5 70.2 70.2 121.7 231.4 229.4 1 5 3 . 4 616.6 61G.3
46 9 17.7 46.3 28.6 78 0 78 0 4 4 . 8 154 9 1 5 5 . 1 6 8 . 5 374.3 373.6 8 2 . 9 590.4 599 7
Ethylvinyldiclilorosilane 44.9 15.5 43.5 7 3 . 5 140.0 130.0 93.4 3 0 6 . 1 3 0 3 . 2 10G 7 465 8 463 3 1 1 7 . 0 628.4 629 1 121.7 7 1 9 . 9 7 1 9 . 0
18 4 18.5 01.1 28 7 28.7 70.0 47.5 81.0 4 7 . 0 87.4 87.4 Q5.5 1 0 5 . 0 1 3 2 . 5 131 0 128 0 270 0 285 2 1 4 8 . 1 535 2 533.8
htalitly evacuated 011one side. This manometer as inadc O i 12-mni. tubing; since t,he pressure was equal to the differeiiw between the two sides of the manometer, meniscus correctioii,* were negligible. Pressure readings xvere made with a Gaert,i~c,r (sathetometer with two telescopes which were compared at a fiducial point for consistency. Pressure readings were reduced io 0" C. The correction to st,andard gravity was not matic sincc it was lees than 1 part in 2500. Temperature control was obtained Iiy immersion of the isotcmiscope in a wcll-st,irred silicone oil bath contained in a SOrip silvered Dewar flask of 4-liter capacity. Two immersion hcaters hlc transformers werc used. Oiic hcatcr p ~ ~ ~ i d ( - : l ree of heat; the other supplied heat when called f w thermoregulator. When required, a cooling coil Temperat,ures w r e rneasurcd with a ca1ihr:itc~tI four junction Lceds and Sorthrup copper constantan thcrmocouple ~ i t tvio h junctions in the constant temperature bath and t ~ inoan ice bath. The e.m.E. of this thermocouple was nicasurc(I with a Kcnner pot,entiometcr. In some of the measurcnioiits . I Bureau of Standards calibrated iiiercury-in-glass thermometer W:LP also used as a check on the thermocouples. Indications ii-ci't: that, t,he temperature measurements \Yere accurate within 0.1 ' ('. The ieoteniecope ivas opcratcd according to the standaixt, method.-that is, the sitmple was boiled repeatedljr a t constajit, temperature until the change in pressure between two succcssivc Ijoilings did not' exceed 0.05 mm.a t the loner pressures or 0.10 nini. a t the higher pressures. The levels of the isotcniscolic ITtube n-ere adjusted by eye. Because of the low density or ~ J K s:tmple a2 compared with mcrcury, this adjustincnt could i)o iii:iclo n-ithin t,he limits of error in reading tho mercury manonidci~. Observation of the U-tube also gave a good indication of the it-nipcrature control, since any fluctuations in the bath tempcrat ur(> resulted in fluctuat,ions of the liquid Icvcls in t h e U-tube. A%sa preliminary check on the experimental method, :i fen. nieasurements m r e made on miter betmecn 50" and 100" C. T h e results agreed n-ith the d a h of Osborne and Mycrs (4)witlr i3.n average deviation of 0.12% in pressure. RESULTS
I n this devicel the bulb containing the liquid sample w a s joined to a U-tube also filled halfrag with the sample. The liquid levels in the U-tube Tyere balanced by thc vapor pressure of the liquid on one side and drv nitrogen pressure on the other. By reducing the nitrogen pressure, air and low boiling impuritics mere removed from the sample and bubbled through the U-tube liquid. Nitrogen was then admitted until the liquid level in each side of the U-tube was equal. The nitrogen side of the Utube was connected t o a pressuie reservoir immersed in a water bath and to an absolute mercury manometer, which nas con-
The experimental data are given in Table I. The constaiits of the hntoine equation m r e determined for each compound by 230) first plott>ingthe experimental data on a log,^ P versus l / ( t scale and t,hen selecting three consistent points for the calculrition of C, B, and A follovr-ing the directions given by Thomsoii ( 7 ) . The remaining points \yere then checked against the cquation. The average deviation betmen the calculsted and 01)served pressures for all t,he data is 1 0 . 8 mm; most of the v d i m
+
November 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLE
111.
2369
VAPOR PRESSURES O F SILICON COMPOUSDS
Temperature, _ C _ ~ ~___~___ 60 mm. 100 inm. 200 inm. 400 mni. 760 in1ii. 59.4 76.4 95.9 (116.8) 48.3 (202.9) I55 2 134 2 (178 6) 120.1 135.2 157 6 (180.6) 115.2 101.7 87 5 108 I (130.4) 56.9 69.1 51.4 70.5 33.2 (6 5 ) (17 2 ) 246.8 222 2 274 8 (304.4) 205 9 37.8 56.0 (75.5) 20.4 9 1 30 4 (98.9) 58.4 77.9 41.5 (160 9) 138 8 117.7 99 2 86 8 (123.7) 51 . o 102.0 81.3 63.1 158.3 (182.3) 135.4 101.8 115 3 (250.3) 228.5 198,6 177.1 163.1 2 3 . 2 (10 9) ( 8 . g ) 6 . 3 -18.7) (66.4) 47.3 13.5 29.3 (3.1) 151.5 175.5 (201 . O ) 130 3 116 3 38.6 (57.3) ( - a 0) 5.3 20.9 14.6 (31.9) -25.8) ( - 1 6 . 2 ) (-1.8) 5.6 21.2 (57 6) 38.9 (-4.7) (90. B) 34.2 51.3 70.5 22.9 1160.5) 86.4 98.9 117.6 138.6 ~~
10 mm. 2~nim. .illyltrichlorosilane CHz=CHCHzSiCla (16.1) (27.5) ClaSiCzHaSiCla 92,Y l3istrichlorosilylethane (77 7 1,2-Dichloroethyltrichlorosilane (75.7) ClCHzCHClSiCla llietliyldichlorosilane (21.0) (CZH5)zSiClz (33 7) l~imethyldichlorosilane ( -24,8) (-13.7) (CH3)zSlClz Dio henyldic hlorosilane (158.4) ( 1 7 5 . 2 ) (CeHs zSiClz C2HadiHClz Etbyldichlorosilane (-24.4) (-12 0) Ethyltrichlorosilane CZH~S~C~J (9.7) (-I.!) 63.4 Etliyltrietlioxysiiane (50.9) CzHaSi(OCzH5) a (28.1) (15.5) Ethylvinyldichlorosilane (CeH5) (CHz=CH SICIS -,-Chloropropyltrichlorosilane C H ~ C ~ C K ~ C H X S I ~ ~ ~( ’6 2 . 3 ) (76 4) (123.0) Hexaethylcyclotrisiioxane (137.1) la (-47.1) (-36 9) LIethyldichlorosilane 1Iethyltriohlorosilane (-27.3) CHaSlCla (-16 5) (75.3) CoHsSiCls (89.8) Phenyltrichlorosilane Sic14 Tctrachloroeilane (-24.4) (-36.1) SiHCla Triclilorosilane (-43.9) (-53,9) (CH43SiC1 ( -21.2) Trimethylchlorosilane (-34.9) CFII=CHSi Cla ( 10.7) (1.3) Vinyltric hlorosilane CHs=CHSi(OCzHs)a (49.4) Vinyltriethoxysilane (62 E) 0 Temperatiires in parentheses arc, abo\ e or below range of experiincntal value. Compound
Formula
&$&El:
-
are within 1 1 . 0 mm., and a few deviations are as large as 8.8 niin. The ilntoine constants are given in Table 11, together with the normal boiling points derived from t,hese constants, and the boiling points of those compounds reported by others. The average deviation between our boiling points and those reported by S h l l (6) is 0.4” C., and for three of the compounds there is exact agreement. The boiling points a t pressures of 10, 20, 40, 60, 100, 200, 400, and 760 mm. of mercury are given in Table 111. All these boiling points were derived from the equations; those in parentheses are above or below the range of the experimental data. ACKNOU IXDGVlhUT
Tiw author? wish to aclrnoirledgr the work of H. C. Givens
40 mm. (40. 1) 109.6
(:;,E?
(-1.4) 194 0 (0.8) (22.3) 77 7 (42.1) 91.9 (152.9) ( - 25 . 5 )
(-4.6)
105.9
(-12.6)
(-32.9) (- 12,3) 14.5 77 2
and E. R. York in the purification of the samples used in these measurements. LITER4TURE CITED (1) Booth, H. S., and Carnell, P. H., J . Am. Chem. Soc., 68, 2G50
(1946). (2) Booth, H. S., and Slartin, TV. F.. Ibid., 68, 2655 (1946). (3) Booth, H. S., and Suttle, J. F.,Ihld.. 68, 2658 (1948). (4) Osborne, K.S., and Myers, C . IS., J . Research Natl. Bur. Staizdards, 13 (1934) (Research Paper 891). ( 5 ) Smith, A., and IUenzies, A. W.C., J . Am. Chem. Soc., 32, 1412 (1910). (6) Stull, D. R., IND.ENG.CHEW,39, 517 (1947). (7) Thomson, G. TV., Chem. Revs.. 38, 1 (1946). (8) Thomson, G. W., “Physical Methods of Organic Cheniistry.” A. Weissberger, ed., 1-01. 1, Interscience, New York. 1949. RECEIVED for review March 22, 19.54.
ACCEPTEDJ u l y 27, 1964.
Flow Properties of Vinyl Chloride Resin Plastisols E. T. SEVERS AND J. $1. AUSTIN Mellon Institute of Industrial Research, Pittsburgh 13, Pa.
0
XE of the best examples of the application of rheology to
industrial problems is found in the development of organic dispersions of vinyl chloride resins. Previous investigators (7-9, 15) have stressed the importance of flow properties in the formulation, manufacture, and application of these dispersions. Plastisols are fluid dispersions of vinyl chloride resin in plasticizer to which desired quantities of pigments, filler, and stabilizers have been added. Plastisols are converted to elastonleric compounds by heating to the point where the resin is solvated by the plasticizer and fused to a homogeneous product. The successful use of vinyl chloride resin plastisols demands a knowlrdge of the flow properties a t the rates of shear encountered during application. High speed roll and knife coating of cloth or paper and die coating of wire or tape subject plastisols to high rates of shear. Even processes such as slush molding and dip coating, ordinarily involving low ratcs of shear, may require pumping of plastisols a t relatively high rates of shear to replenish dip tanks and provide circulation. Mixing operations using roller mills or high energy input mixers will subject the plastisols to high shear stresses.
Flow properties have been measured by rotational viscometers and viscosity cups. Rotational viscometers, however, become quite elaborate when designed for high rates of shear, arid frictional heat buildup becomes serious. Viscosity cups, where the material flows through an orifice under its own head, are limited to measurements a t relatively low rates of shear. Furthermore, irregularly shaped or short orifices make difficult a fundainental analysis of flow data so obtained. An extrusion rheometer is Rssentially a pressurized viscosity cup with a cylindrical orifice. but it is capable of measuring viscosities a t high as well as low rates of shear. The instrument is rugged enough for production control, yet capable of yielding fundamental data. This instrument was used extensively in the present investigation to determine the effect of plasticizer composition and concentration and aging conditions on the flow properties of plastisols. One of the earliest extrusion rheometers put to practical use was the “grease gun” type which Barus ( 2 ) used for investigating marine pitches. Bingham (3) devised a gas-actuated capillary viscometer for measuring the viscosity of a variety of substances
