INDUSTRIAL AND ENGINEERING CHEMISTRY
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solvent 1 to 2, then a slight decrease for solvents 3 and 4. The values are 1.9, 2.8, 2.6, and 2.4, respectively. Davidson and Reid (4) concluded from dilution ratios on cracked and straight-run gasoline fractions that lower boiling fractions of a given gasoline are better diluents than higher boiling fractions. It is clear from the above dilution ratios that this is not altogether true in the case of hydrogenated solvent naphthas. Viscosity tests were made on mixtures of each of the four hydrogenated solvents with RezylllO2 (25 per cent) and with Rezyl 110 (50 per cent). It will be remembered that the ordinary solvency tests (kauri-butanol value, dimethyl sulfate value) indicate that the solvency of the hydrogenated fractions increases with boiling range. It might be supposed, therefore, that the viscosities of hydrogenated solvent-resin mixtures would decrease with increasing boiling point of the hydrogenated solvent. However, this is not a universal run. For example, the solvent mixtures with Rezyl 1102 decrease in viscosity with an increase in boiling range (hence, kauributanol value), whereas the opposite is true with solvent mixtures of Rezyl 110. The two coal-tar solvents tested-namely, toluene and high-flash coal-tar naphtha-give low-bodied mixtures with both Rezyl 1102 and Rezyl 110. With the latter the highflash coal-tar naphtha shows a Gardner-Holt viscosity number A. Hydrogenated solvent 4 mixed with the same resin shows a Gardner-Holt viscosity number F. Yet the kauri-butanol value of hydrogenated solvent 4 is 85.7 vs. 72.6 for the high-flash coal-tar naphtha. Also, both solvents show dimethyl sulfate values of 100, and aniline points of -33” and -20” F. for hydrogenated solvent 4 and the highflash coal-tar naphtha, respectively. With Rezyl 1102 both solvents give Gardner-Holt viscosity number A. Here again it is clearly shown that the solvency tests are not reliable in all instances. These facts apparently point out the necessity for practical trials of solvents for their intended purposes
Vol. 26, No. 6
unless by experience the lacquer or varnish maker knows the particular test that applies to his work. The surface tensions of the hydrogenated solvents increase in the order of their boiling ranges. The results determined on a du Nouy tensiometer range from 24.5 dynes per centimeter for hydrogenated solvent 1 to 34.6 dynes for hydrogenated solvent 4. The surface tensions of the hydrogenated solvents compare favorably with the results obtained for toluene and high-flash coal-tar naphtha. The latter are known to have excellent wetting properties. Thus the above tests indicate that hydrogenated solvents surpass the usual petroleum solvent naphtha in solvency power, and compare favorably with commercial coal-tar solvent naphthas. LITERATURE CITED (1) A. S. T. M., Rept. Committee D-2, 1932. (1A) Boyer, M. W., Chem. & Met. Eng.,37, 741 (1930).
(2) Brunkow, 0. R., IND. ENQ.CHEM.,22, 177 (1930). (3) Cleveland Paint Club, Paint, Oil Chem. Em.,94, 58 (1932). (4) Davidson, J. G., and Reid, E. W., IND.ENQ.CHEM,,19, 977 (1927). (5) Gardner, H. A., “Physical and Chemical Examination of Paints, Varnishes, Lacquers and Colors,” 5th ed., Inst. Paint & Varnish Research, Washington, 1930. (6) Gohr, E. J., and Russell, R . P., J. Inst. Petroleum Tech., 18, 602 (1932). (7) Haslam, R. T., and Bauer, W. C., S. A. E. Journal, 28, 307 (1931). (8) Haslam, R. T., and Russell, R. P., IND.ENQ. CHEM.,22, 1030 (1930). ’ (9) Howard, F. A., Oil Gas J.,30, No. 46,90 (1932). (10) Stewart, J. R., Am. Paint Varnish Mfg.Assoc., Circ. 378 (1931). (11) Sweeney, W. J., and Voorhies, A., Jr., IND. ENQ. CHEM.,26, 195 (1934). RECEIVED October 4. 1933. Presented before the Division of Paint and Varnish Chemiatry a t the 86th Meeting of the American Chemical Society, Chicago, Ill., September 10 to 15, 1933.
Preventing Overheating of Oil Baths HARRY LEVINAND RAYMOND LANARI,Beacon Laboratory, The Texas Company, New York, N. Y.
N
P A N INSULATED
NUT
10-32 LOCKNUT
PER WIRE TO CARRY UlRED CURRENT
yd
ALUMINUM TUBING
PORCELAIN INSULATOR W I T H T W O HOLES
END OF PYREX T E S T
TUBE
FUSIBLE LINK TO S U I T REQUIRED TEMPERATURE
SECTION
‘&K FUSIELEDrl INK SAFETY
VICE
UMEROUS tests conducted in every laboratory-for example, viscosity and oxidation tests -require the use of an electrically h e a t e d oil bath. The need to maintain the heating of these baths over 1o n g-c o n t inu ed periods when personal supervision is inadequate, as at night, creates a r e a l safety problem. If a relay should stick, the t e m p e r a t u r e of t h e oil b a t h might rise to the auto-ignition p o i n t and cause fire.
In order to prevent such occurrence, the authors have devised a fusible link which is incorporated in the electrical circuit of the heating element of the bath. This link is suspended and properly insulated in a thin metal sheath, which in turn is immersed in the oil bath to be protected. When the oil bath attains a predetermined temperature the fusible link will melt, thus breaking the electrical circuit feeding the bath heater. The molten link, instead of falling into the oil, will fall into the glass tube contained in the metal sheath for that purpose. The fusible link can be made of numerous components (1) and in various proportions to yield alloys of different melting points, to satisfy the diverse needs as regards temperature. The accompanying drawing illustrates a convenient form of this device, for use by vertical insertion in an oil bath, which can be constructed for approximately five dollars. LITERATURE CITED (1) Olsen, J. C., “Van Nostrand’s Chemical Annual,” 6th ed., pp. 486-8 (1926). RBCEIVED February 15, 1934.
