€544. A Convenient Solid for Calibration of the Gouy MagneticSusceptibility Apparatus. By B. N. FIGGIS and R. S. NYHOLM. THE measurement of magnetic susceptibilities by the Gouy method is a relative one, the apparatus being calibrated in terms of a substance of known susceptibility, for which water, nickel chloride solution, and powdered cupric sulphate pentahydrate or ferrous ammonium sulphate hexahydrate have been used. The low suceptibility of water is often inconvenient if small tubes are being calibrated. Nickel chloride solution requires accurate analysis before use and ferrous ammonium sulphate is often of questionable purity. This substance and copper sulphate do not pack well and several different values for the susceptibilities of both solids have been reported.The required properties for a calibrant are: (1) Readily available pure;(2) an accurately known and moderate susceptibility (xg = ;(3) stability in moist air;(4) xg must vary in a known and simple way, at least at room temperature; (5) easily and reproducibly packable into the Gouy tube. The complex mercury tetrathiocyanatocobaltate HgCo(CNS), offers some advantages and its susceptibility has therefore been accurately determined. at 20' 1 being used as reference, the gram susceptibility of the complex is 16.44 (-&O.OS) x at 20".As reported elsewhere,l it obeys the Curie-Weiss law, xg cc (T + lO)-l where T is expressed

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is shown to undergo readily the N-methylformanilide aldehyde synthesis, and the compound thus obtained to be 3-form$l-lO-methylphenothiazine. From this aldehyde, several styryl derivatives have been prepared for cancer research, and the thiosemicarbazone and its cyclisation products with various a-halogenated fatty acids have been synthesised for testing as antitubercular substances.THE phenothiazine series offers manifold attractions to pharmacologists, not only because of the several valuable antiseptic and antihistaminic derivatives found therein, but also because the parent compound itself is of strikingly versatile activity. Thus, phenothiazine has been found to be an insecticide (Campbell, Sullivan, and Smith,