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The preparative method for arsenobenzene has been improved. The arsenobenzene-disodium adduct has been prepared and characterized by treatment with methyl chloride, with dimethyl sulfate and with carbon dioxide. By further addition of sodium to the disodium adduct a new type, so-called arsenobenzene-tetrasodium adduct, has been prepared which gives reactions characteristic of phenyldisodiumarsine. This tetrasodium adduct and arsenobenzene exist in mobile equilibrium(2)

The Mercuration of Ethylenes 1993 Silica.-Tlie silica used was Holmes' chalky silica gel prepared in the Severance Laboratory, "Hyflo Super Cel."-A siliceous earth with practically no adsorbent qualities, purchased from Johns-Manville, Cleveland.Nitrogen.-Compressed gas, from the Ohio Chemical Co., Cleveland, containing less than 0.05% oxygen. This trace of oxygen was removed by passing the gas through alkaline pyrogallol. MethodsOur columns were set up according to the diagram in Summary 1.Cholesterol and some other impurities were frozen out of a pentane solution of the nonsaponiliable portion of halibut-liver oil; the resulting solution was then fractionated by Tswett adsorption columns with an improved technique. Using a column of a specially prepared oxygenfree carbon followed by treatment with a column of a new type magnesia a concentrate of vitamin A at least 40% more potent than any previously recorded was obtained.2. Lovibond tintometer readings were checked biologically and spectrographically in the Parke-Davis laboratories and elsewhere.3. The most potent concentrate had a blue value of at least 140,000. Obbrlin, Ohio

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The risks to non-target birds and other wildlife from the use of vertebrate pesticides, including anticoagulant rodenticides, are determined to a significant extent by species' intrinsic susceptibility, and the toxicokinetics of the compounds used. Brodifacoum is highly toxic to birds and mammals. The acute toxicity of brodifacoum to birds in New Zealand varies from <1 mg/kg in pukeko (Porphyrio p. melanotus), the native swamp hen, to >20 mg/kg in the paradise shelduck (Tadorna variegata). Like other second-generation anticoagulants brodifacoum is strongly bound to vitamin K epoxide reductase and will persist, apparently for at least 6 months, in organs and tissue containing this enzyme, e.g., liver, kidney, and pancreas. The unique toxicokinetics of this class of compound exacerbates the risk of primary and secondary poisoning of non-target species. Vertebrate pest control programmes in New Zealand using bait containing brodifacoum have resulted in the primary and secondary poisoning and sub-lethal contamination of non-target species. These include native raptors, such as the Australasian harrier (Circus approximans) and morepork (Ninox novaeseelandiae), other native birds such as the pukeko, weka (Gallirallus australis), southern black-backed gull (Larus dominicanus), and kiwi (Apteryx spp.), and introduced mammals, including game animals. There are increasing numbers of reports worldwide of wildlife contamination and toxicosis after the use of second-generation anticoagulants. All pest control activities require careful risk-benefit assessment in view of their potential to cause adverse environmental impact. Monitoring of wildlife for pesticide residues will provide data that can be used to reduce the risk of anticoagulant bioaccumulation and mortality in non-target species.