small beaker and a mixture of 4 cc. of nitric acid (sp. gr. 1.4) and j cc. of water is added, after which i t is heated on a steam bath t o complete solution. The solution is washed with distilled water into a mercury cathode cup, keeping t h e volume down t o 20 cc. The cathode cup is conveniently made from a j o cc. Erlenmeyer flask. The 20 cc. solution is then electrolyzed under t h e following conditions: CURRENT (maximum), 4 5 amperes at 6 volts REVOLCTIOXS PER MINUTE, 1000. TIME, 45

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... s The initial application of t h e current is I ampere and this is followed b y a gradual increase t o 4 . 5 amperes. Some black masses are seen t o form, but rapid rotation of t h e anode prevents the formation of a large quantity and all disappear. T h e n the black masses have entirely disappeared the rotation of the anode is stopped a n d t h e cathode is washed with distilled water by siphonation while t h e full strength of current is on. The electrolyte should be tested for bismuth with hydrogen sulfide. After z t o 3 washings with water, followed by alcohol, and then by ether, t h e mercury cathode is weighed. The increase in the weight of t h e mercury cathode is due t o t h e bismuth which has been deposited on and amalgamated with the mercury. LABORATORY OF M E R C K 8; COMPANY RAHWAY, X J A rapid and convenient method of determining mercury in mercury salicylates is herewith presented. It consists in a new application of t h e already well a n d favorably known electrolytic deposition of mercury. The method here given as used on salicylates of mercury has been in use about two years and has proved reliable. About o 3 gram is weighed into the mercury cathode dish and dissolved in I O cc. of sodium sulfide solution (sp. g?. about I . IS). To this solution are added 2 0 cc. of I O per cent potassium hydroxide solution. The mixture is now electrolyzed using a current of I ampere a t 7 volts until the mercury is completely deposited, usually about one-half hour being required. The anode should rotate about 500 revolutions per minute. After t h e deposition t h e electrolyte is decanted, t h e mercury is washed with water until free Erom alkalinity, then with alcohol, fifially with ether. and then weighed. LABORATORY OF bIERCK 8; COMPANY RAHWAY, N J. I n carrying on some experimental work recently on t h e gases issuing from t h e roasting furnaces a t one of t h e large Arizona copper smelters, a rapid, accurate a n d convenient method for the quantitative estimation of SO2 a n d SOs was of primary importance. The conditions of t h e work in hand demanded: I-That t h e determination of both sulfur oxides should be made upon t h e same sample of gas. 2-That the time necessary for such determinations should be as short as possible in order t h a t any change in t h e composition of t h e gases given off in consequence of varying conditions in t h e operation of t h e furnaces might be rapidly and continuously determined by one or two operators. 3-That t h e apparatus required should not be too fragile or unwieldy in character b u t capable of convenient transportation t o any poilit of t h e smelter construction. 4-That t h e analytical operations necessary should be of such a nature as t o qdmit of ready performance in t h e field. I n considering t h e various methods, applicable t o this problem, previously proposed or employed by other workers a n d of which we have found any record, it was evident t h a t no one of them fulfilled all t h e requirements of t h e present case. h scheme proposed by Hawleyl for separating SO3 from SOz seemed t o be the most promising. This 1 Enp. Min. Jour., Nov. 23, 1912. p. 987. consists of humidizing t h e gases with HzO vapor t o convert any SOa into t h e white fog of HzS04 and then passing t h e m through a double filter paper held between the large ends of two funnels. This mechanically retains t h e H2S04 and allows t h e SO2 t o pass through. The H z S 0 4 so caught is then determined b y placing t h e filters in a small beaker with about j o cc. of water, adding a drop of methyl orange and titrating with standard alkali. I n support of t h e accuracy of this method Hawley gives t h e following data of tests made b y him in which known amounts of H z S 0 4 were heated in a hard glass tube and t h e fume, mixed with air, passed through t h e filter and t h e acid so caught determined: