that mouse fit with how that control element works under ordinary cir cumstances in mice, Brinster notes. What made this mouse's gene so much more responsive than those of any of its experimental litter mates is unknown, thus raising the possibility that its apparent high degree of con trol may have been fortuitous. The injected genes go into different animals at vastly different chromo somal locations, usually even on dif ferent chromosomes, Brinster and other scientists, including Columbia University's Frank Constantini, are finding. Nonetheless, those genes can take a stable place there, so that they can be passed through the germ line to successive generations of mice. The next big step will be to introduce those genes into specific sites sys tematically. As Brinster sums it up, "There's still a long way to go to get proper regulation." Jeffrey Fox, Washington
CHEMICAL SAFETY
Molten salt baths cited as lab hazards A University of California, Berkeley, lab has been rebuilt and is ready for use again after being demolished in late July by the explosion of a molten salt bath. Berkeley chemistry and chemical engineering faculty mem bers are concerned that many re searchers are unaware of the potential dangers of these commonly used heat-transfer media. The explosion involved a glass polymer-synthesis apparatus im mersed in a fused salt bath containing 3 lb of sodium nitrite and 1 lb of po tassium thiocyanate. The bath had been heated above 270 °C using a hot plate. The experiment was being conducted in a closed fume hood. The explosion, which Berkeley faculty members estimate had the force of about 1 lb of dynamite, caused more than $200,000 damage to the new lab. The doors of the fume hood were imbedded in a wall 20 feet from the point of explosion and the interior walls of the lab were bulged outward. The chemical engineering graduate student conducting the ex periment escaped probable death only because he was bending over to work on a floor vacuum pump at the time of the explosion. Book references to molten salts imply that they may be used freely, according to C. Judson King, dean of Berkeley's College of Chemistry.
Berkeley lab was demolished when a heated nitrite/thiocyanate mixture exploded
"Molten salts are safe—that's the message," he says. Some may be, but others clearly are not. Mixtures of salts for heat transfer are common and are marketed com mercially. Such commercial mixtures contain, for example, potassium ni trate, sodium nitrate, and sodium nitrite. King points out that, in the com mercial mixtures, all of the compo nents are oxidizers. In the mixture that exploded at Berkeley, thiocy anate, a reducer, was included and seems to have triggered the explosion. Mixtures that contain only nitrate and thiocyanate do not seem to ex plode. The explosive reaction in volved nitrite and thiocyanate.
The literature is not of much help in elucidating the problem. The dangers of the mixture are not men tioned in the molten salt safety review in the Journal of Hazardous Mate rials, King says. An extensive litera ture review carried out by King un earthed a 1945 Soviet publication that reported that some mixtures of potassium nitrite and potassium thiocyanate exploded when heated above 370 °C. "A small community of industrial chemists is aware of the dangers of molten salt baths," King says. "However, the information does not seem to have filtered down to the rest of the chemical community." Rudy Baum, San Francisco
Electrocyclic biosynthetic reactions probed Spontaneous formation of a series off thesized seven compounds in the setetracyclic compounds from acyclic,, ries. A sample of one of these led unsaturated precursors in the labo Australian chemists to find their ratory has given support to a theory/ fourth acid. The story that led to discovery of that these compounds arise from aι series of electrocyclic reactions inι this novel electrocyclic biosynthesis nature. If so, this would be one of aι began 25 years ago at the University very few electrocyclic mechanismss of New England, Armidale, New that occur in biosynthesis of natural1 South Wales, Australia. Organic products. The theory itself would1 chemist James E. Banfield received a explain why living organisms makeΒ shipment of stems and leaves of the complex molecules with eight asym Dorrigo plum tree for investigation. metric atoms in racemic form. The Dorrigo plum, which is EndianIt was organic chemistry professorr dra introrsa, is a rare tree that grows K. C. Nicolaou of the University off in the rain forests of New South Pennsylvania, Philadelphia, who re Wales. Banfield was plagued with a lack of ported that generation in situ of theι suspected biogenetic precursors leads5 adequate instruments to investigate to isolation of endiandric acids [J. the structure, and by the very lack of Am. Chem. Soc, 104, 5560 (1982)]. optical activity in the first compound He calls the spontaneous sequence off isolated. Likely structures contained three electrocyclic reactions thatt asymmetric atoms, but it seemed ensue the endiandric acid cascade. improbable that such compounds Four such acids have been isolated to3 from natural sources would be optidate from an Australian tree called1 cally inactive. Banfield enlisted the the Dorrigo plum. Nicolaou has syn- help of organic chemistry professor Oct. 11, 1982 C&EN
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