of still higher sulfur prices are behind TVA's interest in nitric phosphate processes. TVA's efforts, still largely on a bench scale, seek to improve nitric phosphate processes, most common of which is the Odda (named after a Swedish firm which did some of the early development). In the Odda process, ground phosphate rock is treated with nitric acid, the slurry cooled, and calcium nitrate filtered off. The filtrate is ammoniated and processed to a granular product in a conventional TVA ammonia tiongranulation system. The calcium nitrate is converted to ammonium nitrate and precipitated calcium carbonate with ammonia and carbon dioxide. The main difficulties with this process for commercial use are that about a third of the calcium remains in the product and about half of the P 2 0 5 is insoluble. The calcium lowers the fertilizer grade and limits the water solubility of P 2 0 5 . To overcome these difficulties, TVA has brushed off and is modifying an old process—first patented in 1930— to remove the calcium. The process has two basic steps. First, ammonium sulfate solution is added to the phosphate rock-nitric acid mixture; the resulting calcium sulfate precipitate is filtered off and washed with more ammonium sulfate solution. Second, the calcium sulfate is reacted with ammonia and carbon dioxide, calcium carbonate filtered off, and the ammonium sulfate solution regenerated. In batch laboratory tests, TVA
chemists can remove 92% of the calcium and get a product of mostly ammonium nitrate and ammonium phosphates. The P 2 0 5 is 100% citrate soluble (a measure of its potential availability in soils) and about 90% water soluble. The maximum loss of sulfur as sulfate by this process is 26 pounds per ton of product, based on laboratory experiments. This sulfur can be supplied as sulfuric acid or gypsum, for example. Suspension fertilizers continue to attract attention. But initial acidity of suspension fertilizers is high. If acidity is reduced with ammonia, dicalcium phosphate present reverts to fluorapatite, practically the same mineral as mined. To inhibit this reversion, TVA adds a polyphosphate such as an 11-37-0 grade of ammoniated polyphosphoric acid. If 15 to 20% of the P 2 0 5 is added as 11-37-0, no reversion occurs for 45 days. TVA has also found that the polyphosphate must be added during ammoniation when the pH is 2.0 to 2.5, and nearly all the P 2 0 5 precipitated as dicalcium phosphate. Micro- and secondary nutrients can be added to suspension fertilizers within one major limitation—viscosity. Large quantities can be put into suspensions, in contrast with liquids where salting out may be a problem as the temperature decreases. Clay, 2 to 3 % , is added to carry larger-volume secondary nutrients such as sulfur (10 or 20%) and magnesium (3%). Viscosities of the suspensions containing sulfur roughly double after
TVA pan granulator Latest technology for granulation urea
standing a week at 80° F. Viscosities of suspensions containing magnesium triple (from a few per cent), depending on the magnesium compound used. Some suspensions containing magnesium are thixotropic, but pourable.
Photosynthesis—path to food The idea of producing more and better agricultural products by tinkering with the extremely complex mechanisms which control photosynthesis is today little more than a dream. But the eventual importance of such an approach to help relieve the world's food problems must not be underrated, according to the University of California's Dr. James A. Bassham. However, much research remains to be done to bring the dream to reality, he said at the Symposium on Photosynthesis, held to highlight the dedication of International Minerals & Chemical's -S6.5 million Growth Science Center in Libertyville, 111. The Berkeley scientist says that leaves which can be eaten by people may become a much more important crop in the future. For instance, vast crops of jungle foliage could become key food sources if chemical sprays that would enrich leaves in fats and protein can be developed. Dr. Bassham points out that photosynthesis produces not only sugar and carbohydrates but also fats, proteins, fatty acids, and other compounds. Current and future work on the mechanism which controls the distribution of these products—and on ways to manipulate this mechanism—is providing the basis for a new era in agricultural research. So far, a few chemicals, such as methyl octanoate, have been found which reversibly inhibit photosynthesis by deactivating certain enzymes (much as darkness does). Dr. Bassham predicts that lower levels of such inhibitors may bring about "interesting" changes in the quality of photosynthetic products. To date, the pathways from carbon dioxide to the various products have at least been outlined. The variety of regulatory mechanisms have been sketched in. But many complicating factors remain. For instance, he told the symposium of recent work in his Berkeley laboratory on the interaction between photosynthesis and glycolysis—the nonphotosynthetic breakdown of sugars to metabolic intermediates. This work has led to some indications of the role of diffusion of intermediates in the control mechanism of photosynthesis. Earlier studies have shown that OCT. 17, 1966 C&EN 35
some intermediate products of photosynthesis and glycolysis are readily interchangeable. This means one of two things, Dr. Bassham says. One, the intermediates diffuse freely between chloroplasts, the sites of photosynthesis, and cytoplasm, the usual site of glycolysis. Or chloroplasts carry out photosynthesis in light and, by some switching mechanism, some form of glycolysis in the dark. To check out these possibilities, Dr. Bassham and his coworkers have developed a technique for isolating chloroplasts. By this method, isolated chloroplasts give photosynthesis rates as high as 65% of in vivo rates. And they hold this rate for as long as 15 minutes. This performance is good enough to study both the kinetics of intermediate formation and the transport of these intermediates. Using labeling techniques, Dr. Bassham has shown that the intermediate compounds produced with these isolated chloroplasts are high in labeled dihydroxyacetone phosphate ( DHAP ) ; some other compounds are present to a smaller extent. By centrifugation, he has proved that most of these compounds leave the chloroplasts and diffuse into the suspending medium. The California scientist points out that this diffusion is not indiscriminate leakage. Other intermediates, such as fructose-6-phosphate and sedoheptulose-7-phosphate, stay mostly in the chloroplasts. Dr. Bassham notes that DHAP and other intermediates may well diffuse freely between chloroplasts and cytoplasm—as he has shown that they do between chloroplasts and the suspending medium. If so, then various transient changes in intermediates which take place on changes between light and dark can be explained in terms of the glycolysis of photosynthetic intermediates.
Giauque, Hildebrand honored At a quiet ceremony on the University of California's Berkeley campus last week, two of chemistry's elder statesmen received high honors. Buildings were named after Dr. William F. Giauque and Dr. Joel H. Hildebrand. Both are emeritus professors of chemistry at Berkeley. Giauque Laboratory is the new name for the low-temperature research building completed in 1954. Hildebrand Hall, a sparkling new building, opened its doors to freshman chemistry students just this fall. The two central figures of the dedication ceremonies are still active on the Berkeley scene. This in itself is unusual, although the university has named other buildings after professors 36 C&EN OCT. 17, 1966
honor—the Priestley Medal—in 1962. Hildebrand Hall cost $4.5 million. It can accommodate about 1000 students at a time. There are six floors; the building's lower basement has physical chemistry research laboratories. The upper basement houses a computer, physical chemistry and chemical engineering research laboratories, and workshops. It also connects directly with Giauque Laboratory and Latimer Hall; Berkeley's college of chemistry headquarters is in Latimer Hall. On the ground level is a 40,000volume library. The upper floors have teaching and research laboratories and staff offices.
Giauque and Hildebrand Still on the scene
emeritus who were living at the time. More unusual, however, is the fact that Nobel Laureate Giauque was an undergraduate in Dr. Hildebrand's classes at Berkeley back in 1917. Dr. Giauque, who is 71, graduated from Berkeley in 1920. Two years later he won his Ph.D. there for work with Prof. Ernest Gibson on the third law of thermodynamics. His interest in the subject hasn't waned. He is chiefly known for his pioneering low-temperature studies. For example, he was the first to develop the use of magnetic fields to achieve temperatures of hundredths of a degree Kelvin. This work won him the 1949 Nobel Prize in Chemistry. Dr. Giauque designed and supervised the installation of the two underground magnets in Giauque Laboratory. The magnets are unusual because they use circulating kerosine as coolant. Dr. Hildebrand will be 85 next month. He has established himself as something of a legendary figure not only in Berkeley, where he has lived for 53 years, but throughout the nation. He is renowned equally in physical chemistry, education, and public affairs. An authority on the theory of nonelectrolyte solubility, he has coauthored several books and more than 200 papers on the subject. He has been a constructive critic of education at all levels. He lectured in freshman chemistry in 1913 until his retirement in 1952. His "Principles of Chemistry," first published in 1918 and now in its seventh edition, was the first textbook to use the physicochemical approach. He served as President of the American Chemical Society in 1955. His distinguished service to chemistry won him the Society's highest
Wien effect in nervous system An Indiana University chemist and a University of Queensland (Australia) mathematician have come up with a concept to explain the link between the electrical and chemical processes which trigger the action of the nervous system. This problem has long puzzled biologists. According to the concept, the Wien effect—a phenomenon well known to physical chemists—is the key to this link. The Wien effect is a change in the acidity of certain systems brought about by a change in the strength of the electrical field containing the systems. According to Dr. Walter J. Moore, the chemist, and Dr. Ludvik Bass, the mathematician, this effect comes into play whenever a sensory impulse strikes one of the millions of neurons (nerve cells) in the human brain and nervous system. Dr. Moore stresses that what happens when a neuron receives an impulse is well known, but not why it happens.
Chemist Moore Membrane permeability
