March, 1942
INDUSTRIAL AND ENGINEERING CHEMISTRY
9, this expression is useful only to give a rough idea of the manner in which j varies with the initial temperature distribution. Equation 9 was checked experimentally on 603 X 700 cans of 5 per cent bentonite suspension. Before processing, t h e cans were held in water at various temperatures to create the desired temperature gradients. The results given in Table IV show fairly good agreement between experiment and theory.
Nomenclature 2a
= diameter of finite cylinder, thickness of infinite
2b
=
2c
= = =
?(R,’)
mth order Bessel function of 2 thermal diffusivity, square inches/min. = nth positive root of .TO(%)= 0 = temperature of a point on heating curve,
5
T
slab, width of rectangular rism, length of rectangular parallelopiped (!rick), diameter of sphere thickness of rectangular prism, width of brick, length of b i t e cylinder thickness of brick reciprocal of slope of asymptote to heating curve lag factor of heating curve, numerically equal to
( T R - T A ) / ( T R - TO)
O
F.
TO TB Tn u t z,y,z r,e,z
= initial temperature, =I
341 O
heating temperature,
F. F.
O
= temperature a t intersection of asymptote with temperature axis at t = 0 = temperature on theoretical scale; u is related to T by = (TR- T ) / ( T R To) = time, minutes = rectangular Cartesian coordinates = cylindrical coordinates
-
Literature Cited (1) Ball, C. O.,Bull. Natt. Research Counoil 37 (1923); Univ. C&f. Pub. Public Health, 1, 16-245 (1928). (2) Bigelow, W. D.,Bohart, G. S., Richardson, A. C., and Ball, C. O.,Natl. Canners Assoc., Bull. 16L (1920).
Carslaw, H. W., “Mathematical Theory of the Conduotion of Heat in Solids”, Macmillan Go., London, 1931. (4) Jackson, J. M., Proc. Food Conf. Zmt. Food Technoloaists. - . 1940. (3)
39-50. (5) Jackson, J. M., and Olson, F. C. W., Food Research.. 5.. 409-21 (1940). (6) Olson, F.C. W., and Stevens, H. P., Zbid., 4, 1-20 (1939). (7) Schults, 0.T., and Olson, F. C. W., Zbid., 3, 647-51 (1938). (8) Zbdd., 5, 399-407 (1940). (9) Thompson, G.E., IND. ENQ.CHPY.,11, 657-64 (1919). (10) Thompaon, G. E., Phys. Rev., 20, 601-6 (1922). (11) Williamson, E.D., and Adams, L. H.. Ibid., 14, 99-114 (1919).
,
PORCELAIN MANUFACTURE By Paul Kiessling
No.
135 in the Berolzheimer series of Alchemical and Historical Reproductions is from a mural in the Boettger room in the ALBRECHTSBURO: in Meissen. This painting bears the title “Boettger demonstrates the secrets of the manufacture of porcelain to the Elector August (of Saxony) in 1710”. The rediscovery in Europe of the making of porcelain, known for centuriea in China, was undoubtedly a useful outcome of alchemical work. J. F. Boettger was an alchemist operating in Meissen. There is another mural showing him “laboring to make gold” in 1705. Unfortunately this painting was damaged by water some years ago, and can not now be photographed. The artist, Paul Kiwsling, was born in Breslau on January 8, 1839. H e studied in Dresden and Rome, and was a portrait and historical painter. He died in Dresden on January 10, 1919. D. D. BEROLZAEIMER 50 East 41st Street New York, N. Y.
The lists of reDroductions and directions for obtaining wpiss appear aS follows: 1 to 96, January, 1939, page 124; 97 to 120, January, 1941. page 114. 121 to 132 January, 1942,page 119. An additional rebroduction a$ pears enah month.
