T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I K G C H E M I S T R Y . tested from many sides, and the work of H. Nissenson, A. Biltz and 0. Hodthe, and Fresenius quite confirm our results. Cupferron will undoubtedly find extensive application in the quantitative analysis of widely different materials, for it has also been discovered that titanium, cerium, and zirconium may be quantitatively precipitated from acid solutions by it. An example showing the application of the method to a manganese ore may be of value. Dissolve 5.0 grams of the finely pulverized ore in 60 cc. of conc. HC1, oxidize the iron with KClO,, and after expelling the chlorine, dilute t o joo cc. with water. Pipette out 2 5 cc. into a beaker and add 2 0 cc. conc. HC1 and I O O cc. cold distilled water. Allow a solution of about 3 . 0 grams of cupferron in 5 0 cc. of cold water to flow in a fine stream down the side of the beaker, with constant stirring. A brownish red, partly amorphous, partly crystalline precipitate separates out. As soon as a drop of the reagent causes the formation of a snow-white crystalline precipitate, all the iron is down. For certainty's sake add an excess of the reagent, stir well and filter off with suction. In case the last particles of the precipitate cling tenaciously to the beaker, add a little ether t o loosen them, and then remove the ether by adding a little boiling water. In this manner it is possible to quantitatively transfer the precipitate to the filter. The precipitate is nom washed with cold water until the filtrate is no longer acid with the mineral acid used. Manganese may be determined in the filtrate. The precipitate is now washed twice with dilute ammonia ( I vol. conc. ",OH to I vol. H,O) in order to remove the excess of reagent. Wash once more with cold water and fold the wet paper and precipitate together and dry in a weighed platinum or porcelain crucible with a small flame. Then cover the crucible and heat until no more inflammable gases are evolved and then ignite t o Fe,O,, cool and weigh. I. Substance 5 . 0 grams =
I 2'
500
=
20
taken Fe,O, 0.0330
13.2%.
11. Substance 5.0 grams
1
2 j
-=
500
~~
20
taken Fe,O, 0.0331
Sept., 1911
scribed limits are the essentials which determine a good yield. The reduction is continued until the odor of nitrobenzol vanishes. The time required for the reduction depends on the value of the zinc dust. It usually takes half an hour to reduce 60 grams of nitrobenzol. The white zinc hydroxide is now filtered off with suction and the filtrate cooled to o o C. with ice, and ordinary salt (NaCl) is added to saturation. In a little while a thick mass of snow-white crystals forms. Filter off right away with suction and dry the crystals between filter paper. The yield of phenylhydroxylamine is usually about 70-8 j per cent. of the theory. As phenylhy$roxylamine solutions are vigorous skin poisons and may pass through the unbroken skin into the blood, the hands should be washed with water and alcohol in case they come in contact with such solutions. The freshly prepared phenylhydroxylamine is dried for an hour between filter paper and then dissolved in 300--500 cc. of commercial ether. The ether solution is filtered through a dry filter and cooled to o o C. Into this cold solution dry ammonia gas is passed for about ten minutes and then add somewhat more than the theoretical amount (more than I mol.) of fresh amyl nitrite all a t once. The clear solution will suddenly get hot and the entire vessel will be filled with snow-white crystals of the ammonium salt of
nitrosophenylhydroxylamine, I
1 1
\ON*,
\/ ~
The brilliant snow-white crystals are filtered off with suction, washed with ether, and dried between filter paper. They are then to be placed in a wellclosed bottle with a small piece of solid ammonium carbonate. The salt prepared and preserved in this manner will be found a welcome and thoroughly satisfactory precipitating and separating agent for copper and iron in any busy laboratory. UNIVERSITY OF ZURICH. SWITZERLAND. July, 1911
= 13.27~.
The analysis requires about I * / hours, ~ but without inconvenience a number may be simultaneously carried out. PREPARATION OF CUPFERRON.
Sixty grams of nitrobenzol, 1000 cc. of distilled water and 30 grams of NH,C1 are thoroughly stirred up in a wide-mouthed bottle with an efficient stirring apparatus until a milky emulsion is formed. Into this emulsion (constant stirring) add 80 grams of zinc dust (the amount depends on the quality) in very small portions a t a time. During the addition of the Zn dust the temperature must be kept between 1 5 and ~ 1 8 C. ~ This may be accomplished by simply throwing pieces of ice into the rapidly whirling liquid from time to time. Continued vigorous stirring and the keeping of the temperature within the pre-
THE DETERMINATION OF MANGANESE IN VANADIUM AND CHROME-VANADIUM STEELS.' B y J. R. CAIN. Received Yay 2 7 , 1911.
Watters2 has recently described a method for determining manganese in steels containing chromium and tungsten which eliminate the errors caused by using the bismuthate method on such steels, owing to the oxidation of some of the chromium by the bismuthate. The steel is dissolved in sulphuric acid and oxidized with nitric acid, the solution nearly neutralized and the chromium and iron are precipitated with an emulsion of zinc oxide. An aliquot is filtered off,nitric acid added, and the manganese determined 1 Published by permission of the Director of the Bureau of Standards *.Wet. Chem.. Eng , 9, 244 (1911).
T f I E JOI:R,\'dL
Sept., 1911
OF I.Y.DUSTRI.4L A4.1'D E S G I N E E R I N G C H E h f I S T R Y .
b y the bismuthate method as usual. Th:.s method is very similar to one which the writer devised and has used for this class of materials. There is very little choice between the two, apparently, inasmuch as the time consumed, degree of accuracy, etc., is about the same in each case. However, the method to be described might give better results than that; of TVatters on high vanadium products, inasmuch as the vanadium in such cases might not always be completely precipitated by his method and this would cause high results. Watters' method was tested as to this point with the Bureau of Standards chrome-vanadium standard, containing about 1.32 per cent. of chromium and 0 . 2 0 per cent, of vanadium, and no vanadium was found in the filtrate with the manganese. The percentage of manganese in the standard was found to be identical by the two methods. It has already been shown1 t h a t large amounts of chromium and vanadium are completely precipitated from solutions of steel without coprecipitation of manganese, provided the iron is kept mainly in the ferrous condition while the solution is being boiled with the precipitant. To carry out the method for manganese, I or z grams of steel are dissolved in sulphuric acid (IO per cent. b y volume), observing the precautions given in the last-quoted paper, and the chromium and vanadium precipitated by cadmium carbonate as described therein. To the filtrate from this precipitate add 2 5 cc. of concentrated nitric acid and boil till free from fumes. Cool, oxidize with bismuthate, filter through asbestos, reduce with a measured excess (of ferrous solution and titrate as usual. The method is quite rapid, and its use, 01'the use of similar methods which eliminate chromium and vanadium during the bismuthate oxidation, seems called for, inasmuch as the results of the cooperating analysts on the above standard were several hundredths of a per cent. high where the bismuthate method was used. Further, the Ford-TVilliams method also gives high results, apparently due to occlusion o f chromic acid. Some precipitates of manganese obtained by the Ford-Williams method from the chrome-vanadium standard were dissolved in sulphuric acid, neutralized with cadmium carbonate and boiled. The precipitate showed appreciable amounts of chromium when dissolved in nitric acid and oxidized with potassium chlorate. A bismuthate determination of manganese in the filtrate gave a result agreeing with the determinations b y the method of M'atters and that of the writer. B a R B A L r O F ST.4SD.iKDS.
~~.4SHINGTOS.
ON THE SURFACE TENSION OF MOLTEN GLASSES. By
EDWINTVARD T I L L O T S O h . ,
JR
Rweived June 16, 1911
Surface tension has been, up t o the present'time, one of the properties of a glass or enamel of which a comparatively small amount of information is a t hand. Owing to the lack of convenient methods for its del
niIs
JOURNAL.
3, 476 (1911)
631
termination it has been impossible to measure its value and the characteristic effects upon it of each constituent of the glass. This paper is a description of a simple, convenient, and fairly accurate method whereby the surface tension of glasses may be compared. r The method is a variation of that commonly used in the case of liquids, in which the surface tension is calculated from the weight of a drop falling from a tube or a surface of definite size. This method was used by QuinckeI for determining surface tension of easily fusible metals, and a modification of it for those having a high melting point. I n the latter case, small metallic rods or wires were lowered vertically into the horizontal flame of a blast lamp. From the weight of the drop which was formed and which fell, and the diameter of the wire, the surface tension was calculated by means of the following equation, l?i = 2n?'T, in which T is the surface tension, W is the weight of the drop, and 2 7 is the diameter of the rod. Quincke applied this method t o a large number of elements and salts, and recorded one experiment with glass fibers. The method has, however, not been extensively used since i t is not extremely accurate, but it is useful in instances where other methods are not applicable, especially where simple and rapid measurements are t o be made. The ability of this method to give absolute values for the surface tension is doubtful. At first sight i t would appear t h a t the weight of the drop increases until it just overcomes the upward pull of the surface tension, becomes detached and falls. If the problem were as simple as that, the equation given above would hold and the weight of the drops would be proportional to the diameter of the rod, or, in the case of liquids, to the diameter of the tube from which they fall. Tate stated* this as a law, but Lord Rayleigh showed3 that when water is allowed t o drop from various sized glass or metallic tubes, the weight of the drop increases relatively faster than the diameter of the tube up to a certain point, when the weight of the drop remains constant no matter how large the tube or surface from which it falls. Lord Rayleigh also pointed out t h a t the weight of the drop of water is influenced by a number of factors, such as the difference in pressure within the liquid drop from the atmospheric pressure, the physical character of the surface from which the drop is suspended, and the relation of the inner t o the outer diameter of the tube. I t would seem, therefore, that if metallic or glass rods or fibers were used the last two factors, a t least, would be eliminated. In the experiments described in this paper the glass fibers were lowered in a vertical position with the aid of the machine shown in Fig. I . I n this figure, A is a 3/,-inch iron rod 30 inches long, supported by a n iron plate 8 inches in diameter and I / ~inch thick, which is inch iron rod, secured firmly t o the table. B is a
' Pow. A n n . , 184,
356 (1868); I b i d . , 136. 621 (1868).
Phil. M a g . , 27, 176 (1864). Ibid , [.5] 48, 321.
,
