2120
INDUSTRIAL AND ENGINEERING CHEMISTRY
The viscosity data of Archbutt and Deeley (8) also a r e in general higher than those reported in this paper, the greater differences being found with the more concentrated solutions. As with Sheely’s data, the type of viscometer used may explain the major differences. Interpolated values to correspond with the glycerol concentrations used in this paper a r e shown in Table VI. Compared to the present data, the viscosities of glycerol solutions a t 1”C. as determined by Darke and Lewis (IO)are much too low. The differences are greater a t the higher glycerol concentrations, being 1.3% for 10% glycerol, and reaching a maximum of 37.8% for 88% glycerol. Since Darke and Lewis published their d a t a in conjunction with data of Hrrz and Wegner, it is assumed t h a t the specific gravity tables of the iatter authors were used. Glycerol concentrations were recalculated with the Bosart and Snoddy specific gravity tables when comparing the Darke and Lewis data with those of the present authors. The viscosity data of Herz and Wegner (II),with the glycerol concentrations recalculated from the Bosart and Snoddy specific gravity tables, a r e in fair agreemerit with the present data at the lower solution concentrations and lower temperatures but otherwise show considerable irregularity, for the most part being too low. ACKNOWLEDGMENT
This work was sponsored by the Association of American Soap and Glycerine Producers, Inc., New York, N. Y.
Vol. 43. No. 9
LITERATURE C I T E D
Am. SOC.Testing Materials Standards, Vol. IIIA. Tentative Method D 44546T,pp. 964-74,1946. Archbutt and Deeley, “Lubrication and Lubricants,” 5th ed., p. 193,London, C. Griffin & Co., 1927. Bates, F. J., and Associates, Natl. Bur. Standards, Circ. C44, DD.
626.671 11942).
Bi&ham,’E. C., and Jackson, It. F., Bull. Bur. Staiidurds, 14,
NO.298,59-86 (1917). Bosart, L. W.,and Snoddy, A. O., IND. ENG.CHEM.,19,50010 (1927). Rridgman, P. W., Proc. Am. Acad. A r t s Sci., 61,57-99 (1926). Cannon, M. R., and Fenske, M. R., I n d . Eng. Chem., Anal. E d . , 10,297-301(1938).
Cannon, M. R., and Fenske, M . R., Oil Gus J . , 34,S o .4T.pp. 45-46,48-49 (April 9,1936). ( ‘ocks, L. V., J . Soc. Chem. I n d . , 48,279-80T (1929). Darke, W. F., and Lewis, E., Chemistrz/ & Industry, 47, 107.7-02 (1928).
Green, Edrnund, and Parke, J. P., .J. $Sot. Chein. Itid., 58,319-20 (1939).
Hers, W.,and Wegner, A., Z. d m d . Oj2-Fett-Ind., 45,,401-2 (1925).
Lawrie, J. W.,“Glycerol and the Glycbls,” p. 170, New Tork, The Chemical Catalog Co., 1928. Muller, Emma, Sitz. her. A k a d . W’iss. Wieti, Math.-nntia~i.. Klasse, A b L I I a , 133,138-47 (1924). Ruh, E. L., Walker, R. W., and Dean, E:. \V.,Ind. Eng. Chcm., A n a l . Ed., 13,346-9 (1941). Sheely, M. L., IND.ENG. C H E M . , 1060-4 ~ ~ , (1932). Tamrnann, G., and Hesse, W., 2.anorg. allgem. Chem., 156,21857 (1926). Vand, Vladimir, Research, 1, 44-5 (1947). RECEIVED March 18, 1849.
Limits of Flammability - of Paraffin Hvdrocarbons in Air J
M. G. ZABETAKIS, G. S. SCOTT, AND G. W. JONES U . S . Bureau of M i n e s , P i t t s b u r g h , Pa.
A
FLAMMABLE gaseous mixture is a mixture of gases through which flame can propagate. The flame is initiated in the gaseous mixture by means of a n external source that delivers energy to the system, composed of the gaseous mixture and its surroundings. A flammable gaseous mixture may apparently or actually be rendered nonflammable by a change in one or more of the following items associated with the mixture or its surroundings: ( a ) Temperature
( b ) Pressure (c) Ratio of combustible t o oxygen ( d ) Ratio of inert or other foreign gas t o oxygen ( e ) Characteristics of the ignition source (f) Geometry and size of the confining vessel ( 9 ) Physical state and surroundings of the gaseous miuture
Although a suitable change in one or more of the above itenis may render a flammable mixture nonflammable, the converse is not necessarily true. As in general only gaseous mixtures composed of one combustible and air are considered in this investigation, item d is constant and will not be considered further. Furthermore, if all thc above items are kept constant excc,pt c, which is varied by adding air, the combustible content of thc flammable misturc cvcintu:dly becomes too low t o propagate flamv. If then a nuinb(1i.o f siinilar tests are made in which e , f , and g are also varied ( : ~ l t h ( ~ u g h the gaseous niixturo should roni:~inhoniogciicwus :III(I
