THE ANALYST. 243 INORGANIC ANALYSIS. On the Quantitative Determination of Arsenic by the Marsh Method. G. Bertrand and Z. Vamossy. ( A m . Chim. Phys., 1906, 523; through Chem. Zeit., 1906, xxx. [Rep.], 141.)-The method gives good results, provided that the authors’ instructions ( A m . Chim. Phys., 1903, 242) are used with the modification that a length of 40 cm. of the tube is heated and that the tube has a bore of 2 mm. For quantities of 0.01 gram arsenic and more, the gas, after leaving the apparatus, is passed through a solution of silver nitrate, The arsenic mirror should be dissolved in sodium hypochlorite and not in nitric acid. A. G. L. On a Method for the Detection of Very Small Quantities of Yellow Phosphorus. R. Schenck and E, Scharff. ( B e y . , 1906, 1522; through Chem.Zeit., 1906, xxx., [Rep.], 156.)--Yellow phosphorus, even in very small quantities, ozonizes air, and hence may be made to discharge an electroscope ; phosphorus trisulphide, even when luminescent, does not possess this property, and does not yield any phosphorus trioxide on glow com- bustion at moderate temperatures. The authors make use of the apparatus shown for the detection of small amounts of yellow phos- phorus. By means of a tube passing through the ground-glass stopper of the tube (a) a slow current of air is led over the sub- stance to be examined, which is placed at the bottom of the tube. The air then passes through the vessel (c), which communicates by means of its removable stopper (d) with an electroscope (b). A piece of sodium in the tube (e) serves t o keep the electroscope dry and sensitive.A. G. L. Determination of Small Quantities of Copper in Water. E. B. Phelps. ( J o z ~ m . Amey. Chem. SOC., 1906, xxviii., 368-372.)-The copper is separated electro- lytically from an acid solution, dissolved in dilute acid, and, after neutralizing, determined colorirnetricslly as sulphide. Sufficient water to contain 0.1 to 1.0 mgm. of copper is evaporated to 75 C.C. and washed into a platinum dish, which serves as anode, adding 2 C.C. of dilute sulphuric acid for clear and soft waters, 5 C.C. for those rich in organic matter or clay. The cathode, consisting of a flat spiral of stout platinum wire, is then suspended in the solution parallel to and about $ inch from the bottom of the dish, and the circuit closed. After electrolysing for four hours with occasional stirring, using it current of 0.02 amphe, the cathode is removed without244 THE ANALYST.first opening the circuit and immersed in dilute nitric acid previously heated to boiling. The spiral is washed and the liquid evaporated to dryness on the water-bath, a few drops of hydrochloric acid being added if silver is suspected. The residue is then dissolved in water, washed into a Nessler glass, made up to 100 c.c., and 10 C.C. of an alkaline solution of potassium sulphide, prepared by mixing equal volumes of 10 per cent. potash solution and a saturated aqueous solution of sulphuretted hydrogen, added. A similar tube is prepared by adding 10 C.C. of the reagent to a tube of distilled water, and then running in, 0.2 C.C. at a time, a standard solution containing 0.2 gram copper per litre. This method gives good results in the presence of sewage and industrial waste, iron, lead, silver, and tin, and in highly-coloured surface-waters. W. H. S.