Sept., 1 9 1 1
,
T H E Jt3I;‘Rn’rlL OF I h - D U S T R I L 4 L A-VD E N G I N E E R I N G C H E M I S T R Y .
and allowed to starid in a dustless section of the laboratory for one month. The oil-pigment paste from each beaker was then separately extracted with benzine to remove the linseed oil from the pigment. The benzine solutions of oil were then heated t o remove the benzine and the residue of oil burned to ash in crucibles. The ash from each test was weighed, and if it ran above the percentage of ash determined on a blank sample of linseed oil (namely, 0 . 0 0 3 per cent.), the ash was analyzed qualitatively for metallic constituents. The following table of results shows the percentage increase in ash, as well as the constituents of ash on thg various samples tested: TABLE OF
RESULTS
Per cent. of ash in oil extracted from oilPigment in oil. pigment paste. Raw linseed oil without Blanc fixe.. . . . . . . . . . . . . Silica.. . . . . . . . . . . . . . . . . Asbestine. . . . . . . . . . . . . . China clap. . . . . . . . . . . . .
.....
Lithopone. . . . . . . . . . . . . . Prussian blue. . . . . . . . . . .* Sublimed white lead.. . . . Zinc‘oxide.. . . . . . . . . . . . . Corroded white lead.. . . Red lead, . . . . . . . . . . . . .
Analysis of ash.
............ ............ 0.003 0,003 0 005
............
0.007 0.008
............
0.03 1
0.032 0.033 0.105
0,116 0 . 2 1 12
............ ............
............ Lead oxide iPbO) Zinc oxide (ZnO) Iron oxide (Ft:2O3) Lead oxide (PbO) Zinc oxide (ZnO) Lead oxide (PbO) Lead oxide (PbO)
Observation of these results shows that pigments such as barytes, blanc fixe, and silica have n o chemical action on the linseed oil. The results Ion asbestine and China clay also are negative, the extremely slight increase in amount of ash from these samples probably being due t o traces capried over mechanically into the oil mixture, the last named pigments being more fluffy and difficult t o separate From oil. Slight action seemed to be apparent in the case of whiting, a pigment somewhat alkaline in nature. A longer test might have shown this pigment t o have possessed still greater action. Sublimed white lead, a paint pigment considered of great value by the paint grinder, for use with tinted paints which are liable t o destruction when ground with alkaline pigments, showed but little action on the linseed oil. Corroded white lead, ivhich is well known t o be quite alkaline in nature, showed considerable action, indicating that the formation of lead linoleate or some other organic lead compound takes place w;?en this pigment is ground in oil. Zinc oxide and lithopone, the latter pigment containing 30 per cent. of zinc sulphide, both indicated action on the oil. Chrome yellow (chromate of lead) showed some action, as did also Prussian blue, the ash from the last named pigment showing a heavy percentage of iron oxide. Red lead showed a most astounding gain in these tests, chemical action of the pigment on the oil being apparent soon after the tests were started, as shown by ,the formation of a hard cake with the linseed oil. The raw linseed oil which was used in these tests had an acid value of I . 84 which is very low. The neutralization of this free fatty acid by some of the
629
alkaline pigments used may account for part of the increased percentage of ash. It is the writer’s belief, however, that in many cases the pigments, and more especially the basic pigments, had a direct saponifying action upon the glycerides of the oil. Summing up the results, i t is fair to say that the inert pigments so-called are really inert chemically, and that the lead and zinc pigments are chemically active. It would seem advisable, therefore, to use in paints made of the chemically active pigments a moderate percentage of the inert pigments, so that any marked saponification would not take place. The saponification of oil by either lead or zinc pigments is a p t t o result in early disintegration, as shown by exposure tests.1 These same tests have proved that marked saponification may be prevented by the use of moderate percentages of the inert pigments. THE INSTITUTE OF INDUSTRIAL RESEARCH. WASHINGTON, D C
CUPFERRON: ITS USE I N QUANTITATIVE ANALYSIS. BY
OSKAR BAUDISCH A S D VICTOR
L. KING.
Received July 24, 1911.
Under the name “Cupferron” one of us ( 0 . B.) introduced the ammonium salt of nitrosophenylhydroxylamine, C,H,(NO)ONH,, into quantitative analysis as a precipitant for cupric and ferric ions. By means of cupferron, iron and copper may be . separated very rapidly and exactly, not only from one another but also from almost all the other metals. The new method exceeds in elegance, simplicity, and rapidity of operation all the methods known up to the present time for the separation of iron and copper, and has already met with great favor in technical chemical analysis in factories and mining and metallurgical plants. The advantages of precipitating with cupferron are as follows: I. Iron and copper are precipitated from solutions strongly acid either with mineral or acetic acids. The precipitated iron and copper salts may be very easily and thoroughly washed free from the chlorides, nitrates, sulphates, etc., of any other metals which may be in solution. 11. The precipitates settle rapidly and may be filtered off without loss of time. 111. The separation of the iron from the copper is accomplished simply by washing the precipitate on the filter with dilute ammonium hydroxide solution. The ferric salt is completely insoluble and remains on the filter. IV. The iron salt is readily soluble in ether, chloroform, acetone, etc., and may be dissolved, on the filter, away from any other metallic salts such as Pb, Ag, I-Ig, Sn salts, which may have been simultaneously precipitated. The particular value of the new method lies in the fact that by its means iron may be rapidly separated from aluminum, manganese, chromium, nickel and cobalt. The “cupferron” method has been thoroughly See Bulletzits 26 and 28, Paint Mfrs ’ Assn of U S
\
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).
