A. J. Haagen-Smit

Photochemistry and Smog

An overview is presented of the new aspects in air pollution. Experimental data, as well as air pollution episodes involving smog and photochemical reactions are reviewed. Investigations of the smog mechanism have been carried out mainly with oxides of nitrogen and pure hydrocarbons, and on the basis of these experiments there is general agreement that the primary process in smog reactions is a photochemical dissociation of nitrogen dioxide with the formation of nitric oxide and atomic oxygen. The most reactive organic compounds are olefins and diolefins and they are the most frequently used in photochemical studies. Some of the less reactive species, such as aldehydes, aromatic compounds, and saturated hydrocarbons, also contribute to the production of ozone.

Ozone Cracking in the Los Angeles Area

Abstract Cracking of rubber, due to the presence of ozone, was determined in the Los Angeles area by measuring the number of cracks and the crack depth after exposure of standardized bent rubber strips to the atmosphere. The cracking shows a daily and seasonal variation due to the difference in ozone concentration as well as difference in temperature. Results over a three year test period are presented, as well as a comparison with oxidant and ozone values measured in the same area. The ozone concentration usually reaches a maximum during the day and is highest during the summer months. Its origin has been traced to the action of sunlight on mixtures of organic material and oxides of nitrogen, common air pollutants in urban areas. A comparison with chemical measurements of the oxidizing power of the air shows a similar trend. The rubber test is useful in the correct interpretation of outdoor exposure tests of rubber goods, since it integrates the variable action of ozone due to large fluctuations in its c...

Effects of Salts on Emergence from the Cyst in Protozoa

THE physiology of encystment and excystment of Protozoa and other micro-organisms has received little attention. In the case of the ciliate Colpoda cucullus, it has been earlier shown1 that emergence from the cyst, or excystment, is brought about by some special substances present in the excysting medium, which is usually hay infusion. Part at least of the active material was shown to be ether-soluble. We have therefore subjected hay infusion to fractionation in order to isolate and identify the active excysting substance.

Sesquiterpenes and Diterpenes

The study of terpenes is intimately connected with the development of organic chemistry. In the early years of terpene research the peculiar structures of this type of compounds posed formidable problems for which methods of attack had to be invented; and the organic chemist of today owes a great deal to the pioneers in this field such as Wallach, Semmler and many others.

The essential oil of pectis papposa

This oil, produced by a heavily scented herbaceous plant of the American Southwest and northern Mexico, is rich in cumaldehyde and carvone, and is therefore a potential commercial source of these fragrant aldehydes, now obtained from cumin, caraway and dill seed oils and used in Savoring food and beverages.

XANTHURENIC ACID AND ITS ROLE IX THE TRYPTOPHANE METABOLISM OK PYRIDOXINE‐DEFICIENT RATS

In a previous publication (1) the isolation of a green pigment from the urine of pyridoxine-deficient rats was described. The green pigment was shown to be the product of a reaction between ferric ammonium sulfate or other ferric salts and a compound whose nature was unknown. This compound has now been isolated in crystalline form. It is a yellow pigment and has been identified as xanthurenic acid.

Atmospheric Ecology II: The Troubled Outdoors

The discoverer of the essential fraction of air, a young minister of the Dissenting Church in England, Joseph Priestley, wrote as follows: “My reader will not wonder that after having ascertained the superior goodness of dephlogisticated air by mice living in it I should have the curiosity to taste it myself. I have gratified that curiosity by breathing it. The feeling of it to my lungs was not sensibly different from that of common air but I fancied that my breast felt peculiarly light and easy for some time afterwards. Who can tell but that in time this pure air may become a fashionable article in luxury. Hitherto only two mice and myself have had the privilege of breathing it.”

Essential oils—a brief survey of their chemistry and production in the united states

Essential oils can be produced in this country, but extensive investigations and careful planning are of prime importance.