Glass
Safety Cap for Laboratory
Distillation Equipment
GEORGE A. RADER, Standard Oil Co. of California, Richmond, Calif. slightly to release the Bask pressure, and then to reseat itself. Along with the vapor a small amount of atomiaed liquid may be released from the Bask but the force of the discharge tends to direct the mixture upward and away from the burner flame. If, during the distillation, the flesk pressure forces the release of the safety cap, the operator can shut down and correct the cause of pressure build-up. FILLING STEM CAP
THERMOMETER STEM CAP
cI!'-d
Figure 1
0
N E common cause of damaging fires in petroleum laboratones IS the accidental building up of excessive pressure in distillation flasks. Such Basks are usually equipped with two stems or necks, one used as the filling stem and the other for a thermometer. Both openings are ordinarily closed with a cork. During the distillation the reflux column or condenser may become plugged, there may be a sudden formation of foam, or the operator m y neglect to open a vent liue, thereby causing unusual pressure to build up in the flask. When this occurs one cork may be forced out, releasing an appreciable volume of flammable vapor plus liquid which Bashes, aud the result w a laboratory fire. A safety device (Figures 1 and 2) has been developed for the purpose of preventing such fires. One device is attached to each stem and acts as a safety valve by permitting the cork to lift "
- pa-.
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I
Figure
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During the tests and demonstrations on Isboratory distillation equipment, no flashes or fires resulted, but it is believed that under some conditions a flash is possible. The total amount of stock released, however, is generally so small that serious con3equences are not likely to result.
Improvements in the Determination of Iron by the Nitroso
R
Salt Method
C. P. SIDERIS, H. Y. YOUNG, AND H. H. 0. CHUN, Pineapple Research Institute of Hawaii, Honolulu, T. H.
THE
sensitive to selection of a new light filter which is the color of the iron salt of l-nitroso-2-h~~x~-3,6-naphthalene disodium sulfonate and the introduction of certain improvements in the nitroso R salt method for iron (1) have made necessary revision of the original procedure.
PmcEnm, Add to a ali uot ofthe u*nom in a ml. Pyrex test tube, 0.5 ml. of 104 hydroxylamine sulfate and a drop of 0.05'% rnet.mil yellow (aqueous solution) and neutralize
color intensit in the photoelectric colorimeter from 2 to 24 hours later, using Ater KS66 with transmission limits of 640 to 700 millimierous and a 2.5-mm, cell or a of a lo-mm, and a 7.5-mm. plunger as recommended for the Summerson-Klett photoelectric colorimeter. The IO-mm. cell is recommended for concentrations helow 1 microgram per ml. A good linear relationship between concentration and colorimetric reading exists UP to 10 micrograms of iron per milliliter. LITERATURECITED
~ ~ ~ ~ ~ ~ ~ o . , add one drop of 6 N hydrochloric acid.) Then add to the mixture 1 ml. of 0.5% nitroso R salt End 2 ml. of 4 N sodium acetate and dilute to a definite volume, in the range of 20 ml. Determine 276
(1) Side&, C. P.. IND.ENO.CHEX.,ANAL ED..14, 756 (1942).
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the approval of the .4eting Director lls Technical paper the ~ i n e a o p l eResesreh Institute of Hatiaii. University of
P U B L I B ~ D'with
y
