Oct., 1921 THE JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY 939 CONCLUSIONS Modifications in bleaching methods give promise of greater The chemical characteristics of soda and sulfate pulps result,s than modifying cooking methods. indicate that they are a very pure form of wood cellulose and Modifications in which the bleaching operation was divided capable of high yields of white fibrous and resistant material. into two steps, with washing between steps, cut the bleach The sulfate process is much more efficient than the soda requirement in two. process in yielding a bleachable pulp from coniferous wood. Pulps of better quality, both from physical and chemical The coloring matter in pulps is of the nature of a dye and considerations, are obtained by cooking the wood as little can be removed without materially reducing yields. Most as possible in isolating the fibers and by accomplishing as of the action in cooking to reduce bleach consumption is to much of the burden of purification as possible in the bleaching dissolve and degrade the cellulose. and washing operations.

The Determination of Vanadium and Chromium in Ferrovanadium by Electrometric Titration' By G. L. Kelley, J. A. Wiley, R. T. Bohn and W. e. Wright MIDVALESTEEL & ORDNANCE C0.p NICETOWNPLANT, PHILADELPHIA, PENNSYLVANtd The object of this paper is to describe a method for the When the vanadyl sulfate is titrated at 80" C. with perman- determination of vanadium in ferrovanadium not subject ganate in a similar acid concentration, the change of poten- to interference by chromium, which is so often present. Kel- tial is about 60 mv. Under these conditions the color of ley and Conant2 described the electrometric titration of permanganate is not visible until about 0.20 to 0.25 cc. more vanadium following oxidation with ammonium persulfate of the permanganate solution has been added. The poorer and silver nitrate, but the method did not provide against quality of the work done with permanganate may be due ts the possible presence of chromium. Kelley and the collab- the incompleteness of the reaction between the permanganic orators3 above named described a method for the selective acid and vanadyl sulfate, and the results are, doubtless, oxidation of vanadium in steel in the presence of chromium, affected by the exposure of the hot solution to air during using nitric acid as an oxidizing agent. At that time, how- titration. ever, we were not prepared to recommend the application NITRIC ACID OXIDATION-The solution of vanadyl sulfate, of our procedure to the determination of vanadium in ferro- standardized as above, was used to check further the degree vanadium. Since then its application to the analysis of of oxidation effected upon vanadyl salts by nitric acid. 13 this alloy has been studied. our earlier paper on the selective oxidation of vanadyl salts PRELIMINARYEXPERIMENTAL WORK by nitric acid in the presence of chromic salts, it was sug- gested that the vanadium be considered approximately 99 DETERMINATION OF VANADIUM IN AMMONIUM VANADATE- per cent oxidized. Our more recent work leads to the be- A large volume of solution was prepared from ammonium lief that the degree of oxidation is more nearly 99.5 per cent. vanadate described by the maker as C. P. This was analyzed With the object of simulating conditions which would obtain by two methods. In the first, the vanadium was determined if the work were done upon ferrovanadium, solutions were by titrating the solution with ferrous sulfate and dichromate, prepared containing 0.3 g. of pure iron, 0.1273 g. of vanadium taking as the end-point the point of greatest change in the as ammonium vanadate, 25 cc. of sulfuric acid (sp. gr. 1.58), oxidation-reduction potential. The potassium dichromate 40 cc. of nitric acid (sp. gr. 1.40), and water enough to make solution was made from a C. P. salt which had been re- the total volume 200 cc. The iron was first dissolved in the crystallized and fused. It was also compared through the sulfuric acid and water in the presence of the ammonium ferrous sulfate with permanganate which had been standard- ized against sodium oxalate. The average difference be- vanadate, thus reducing the latter to vanadyl sulfate. The tween these standardizations was less than one part in one mixture was boiled for 1 hr., at such a rate that the volume was 100 cc. at the end of the period. It was then cooled to thousand. In the second method, 100 cc. of the ammonium 5" and titrated electrometrically with ferrous sulfate and vanadate solution were placed in a flask, with an equal vol- C. potassium dichromate. Out of twenty-four determinations ume of water and 5 cc. of sulfuric acid (sp. gr. 1.58); and treated with sulfur dioxide for 20 min. at the boiling temper- made, the value found for percentage oxidation was 99.3 in four cases, 99.5 in eleven, 99.6 in six, and 99.7 in three. ature. The excess of sulfur dioxide was removed by passing The average was 99.5 per cent oxidation, with a maximum purified carbon dioxide through the still boiling solution for an additional 20 min. Two hundred cc. of a boiling water variation of 0.2 per cent above and below. solution containing 50 cc. of sulfuric acid (sp. gr. 1.58) were We have previously shown' that chromium is not oxidized next added, and the mixture was titrated hot with 0.05 N under these conditions. We have made a further investigation of the effect of con- permanganate using the potentiometric end-point. Eight determinations by the first method gave 0.1273 and 0.1274 ditions upon the oxidation of vanadium by nitric acid, but inasmuch as our results were largely negative, they need not g. of vanadium in 100 cc. of solution, the average result being nearer 0.1273. The solutions titrated with perman- be described in detail. Oxidations conducted in flasks at ganate after sulfur dioxide reduction did not agree so well. the boiling temperature, with air passed through for 6hrs., The results ranged from 0.1269 to 0.1275, averaging 0.1272. did not show consistently higher oxidation than solutions The condition most favorable to titration with ferrous boiled 1 hr. in beakers covered with watch glasses. When sulfate is an acid concentration of about 50 cc. of sulfuric air was excluded, the results were slightly lower. acid (sp. gr. 1.58) in a volume of 350 cc. at a temperature METHODFOR DETERMININGCHROMIUM AND VANADIUMIN of 5" @. Under these circumstances the change in potential FERROVANADIUM for 0.05 cc. of the ferrous sulfate solution (23 g. ferrous am- Dissolve 3 g. of ferrovanadium in 75 cc. of nitric acid (sp. monium sulfate in one liter) is about 50 mv. at the end-point. gr. 1.13). When solution is nearly complete, add 10 cc. of hydrochloric acid (sp. gr. 1.20). When the amount of 1 Received April 13. 1921. * J. Am. Chem. Soc., 88 (Isle), 349. silicon is large, it may be convenient to add a few drops of *Tars JOURNAL, 11 (1919), 632. 1 LOG. ci). 940 THE JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 13, No. 10 hydrofluoric acid to bring about solution. Next add 50 cc. sponding to chromium but expressed in terms of vanadium. of sulfuric acid (sp. gr. 1.58) and evaporate until fumes ap- Dividing this by 2.943 gives the percentage of chromium. pear, to remove nitric and hydrochloric acids, and to com- The use of the factor 2.943 may be avoided if 2.883 g. of plete the decomposition of vanadium carbides. The in- potassium dichromate are used to prepare the solution. In soluble residue after this treatment is generally small and this case each cc. corresponds to 1 per cent of vanadium consists chiefly of aluminium oxide. Ordinarily no loss of when the sample titrated contains 0.3 g. of the ferro-alloy. vanadium occurs if it is disregarded, but it may be dissolved APPLICATIONOF METHOD in water after fusion with sodium peroxide. The alkaline The application of this method to the analysis of two solution so obtained should be boiled for at least 15 min. samples of ferrovanadium known to contain chromium gave to remove hydrogen peroxide. The solution may then be the following results: acidified with a slight excess of sulfuric acid and added to the Chromium and Vanadium main filtrate. This solution is then cooled and made up to -as Vanadium-- -Vanadium- SAMPLE Per cent Average Per cent Average a volume of 1000 cc. One hundred cc. portions of this solution. A 41.29, 41.32, 41.34 41.32 33.05,33.13, 33.09 33.09 corresponding to 0.3 g., are convenient quantities for subse- B 48.29, 48.36 48.32 43.30,43.36, 43.40 43.35 quent work. By calculation from the averages, Sample A contained DETERMINATION OF VANADIUM AND CHROMIUM-TOa 2.80 per cent of chromium, and Sample B contained 1.61 100-cc. portion add 25 cc. of sulfuric acid (sp. gr. 1.58) and per cent. water enough to make the volume 300 cc. Heat the solution To check the accuracy of this method of determining to boiling and add 20 cc. or more of a 10 per cent solution of chromium in ferrovanadium, a procedure which separated ammonium persulfate and 10 cc. of a 0.25 per cent solution of most of the vanadium was devised. It had the advantage silver nitrate. Boil the solution at least 10 min. to oxidize of permitting work with a much larger amount of chromium the vanadium and decompose the excess of ammonium per- in the presence of a greatly diminished percentage of va- sulfate. If there is no manganese in the ferrovanadium, nadium. For this purpose 1-g. samples of ferrovanadium some should be added, as the persistence of the color of per- were dissolved in hydrochloric acid (sp. gr. 1.10)) and oxi- manganic acid is a good indication that the amount of am- dized with nitric acid. The solution was evaporated to a monium persulfate added has been sufficient to complete sirupy consistency, when a second portion of hydrochloric the oxidation of all chromium and vanadium. After 10 acid was added and the evaporation repeated. Iron was min. boiling, add 5 cc. of hydrochloric acid (1 : 3), and con- extracted from this with ether, and the aqueous solution tinue the boiling 5 or 10 min. longer. In this way the per- evaporated with sulfuric acid until fumes appeared. It manganic acid is completely destroyed without reducing was then diluted to 160 cc., and 40 cc. of nitric acid (sp. gr. either chromium or vanadium. After the addition of a 1.40) were added. Boiling this solution under the prescribed further 25 cc. of sulfuric acid and cooling to 5" C., the solu- conditions oxidized nearly all of the vanadium and no chro- tion may be titrated electrometrically. It is convenient mium. To the cool solution, sodium carbonate was added to use for the titration the solutions used in titrating chro- to precipitate iron and chromium, along with some man- mium in steel. As described in the previous paper, these ganese and a small amount of vanadium. The precipitate are made by dissolving 2.828 g, of potassium dichromate was washed and dissolved in nitric acid and a little water. in water to make 1000 cc., and by dissolving 23 g. of ferrous The resulting solution was made up to a volume of 200 cc. ammonium sulfate and 100 cc. of sulfuric acid (sp. gr. 1.58) after the addition of 40 cc. of nitric acid (sp gr. 1.40), and in enough water to make 1 liter. The dichromate solution 25 cc. of sulfuric acid (sp. gr. 1.58). After a second ox- is used for reference and the ferrous sulfate solution compared idation of vanadium by boiling, the chromium was again with it electrometrically at the time the work is done. precipitated. This precipitate still contained vanadium, When a high degree of accuracy is desired and the conditions but only in avery smallamount. It could have been com- under which the work is carried out require it, the dichromate pletely removed by oxidizing the chromium with ammonium should be purified and fused before weighing. Each cubic persulfate and precipitating the vanadium with uranium, .centimeter of this dichromate solution is equivalent to 0.001 as described elsewhere by US.^ This did not seem necessary, g. chromium or 0.002943 g. vanadium. When the ferro- and we, therefore, resorted to the easier procedure of de- vanadium oxidized as described above is titrated with ferrous termining the amount of vanadium present. The vana- sulfate and dichromate, both chromium and vanadium are dium in the precipitate was oxidized with nitric acid in the titrated. Multiplying by 2.943 and dividing by 3 gives the usual way, and titrated with ferrous sulfate. The amount apparent percentage of vanadium, which includes both of vanadium so found varied with different samples, but vanadium and chromium. averaged about 0.4 per cent, After titrating the vanadium, each solution was evaporated until sulfuric acid fumes ap- DETERMINATION OB VANADIUM-The vanadium is de- peared, after which it was diluted and both vanadium and termined in a separate 100-cc. portion. During the evap- chromium were oxidized with ammonium persulfate. The oration of the nitric acid solution with sulfuric acid, a slight amount of chromium waslarge enough to require about 17 to oxidation of chromium may have occurred. It is, therefore, 30 cc. of our ferrous sulfate solution for its titration, thus per- desirable to add a few cc. of ferrous sulfate solution to reduce mitting a very accurate determination of combined chro- this. After a few minutes boiling, add 20 cc. of sulfuric mium and vanadium. By subtracting the vanadium pre- acid (sp. gr. 1.58), and 40 cc. of nitric acid (sp. gr. 1.40), viously determined on each portion from the total of chro- together with enough water to make the volume 200 cc. mium and vanadium, new figures were obtained for the chro- Place a label on the beaker marking the 100-cc. level, and mium present. In Sample A: chromium was found as 2.79, boil at such a rate that the volume is reduced to 100 cc. in 2.77, and 2.77 per cent, which is in good agreement with 1 hr. Dilute the solution with ice water and cool to 5O C. 2.80 found by the fist method. Sample B gave 1.62,1.61, to titrate. Divide the titration result by 995 and multiply and 1.59 per cent, against 1.61 previously found. by 1000. Divide the product by 3 and multiply by 2.943. SUMMARY This gives the actual percentage of vanadium. 1-The authors have confirmed the identity between the CHROMIUM BY DIFFERENCE-BY subtracting the actual electrometric end-point value obtained by titrating vana- percentage of vanadium from the percentage representing dium with ferrous sulfate and by titrating pure solutions both chromium and vanadium we obtain a figure corre- 1 THISJOURNAL, 11 (1919), 632. Oct., 1921 THE JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY 94 1 of vanadyl sulfate with permanganate when suitable blanks of vanadium in ferrovanadium containing chromium. we used in the later titration. &The authors have shown that the amount of chromium 2-It is demonstrated that the oxidation of vanadium by can be determined with accuracy from the difference between nitric acid under a fixed set of conditions gives a very regular the titrations after oxidation with silver nitrate and am- degree of oxidation. monium persulfate and after oxidation with nitric acid. 3-It has been previously shown that chromium is not 6-Results have been given showing the chromium ob- oxidized under the conditions described. tained after separating nearly all of both vanadium and 4-A method has been developed for the determination iron.

Effect of Variation in Analytical Constants of Linseed and Soy-Bean Oils upon the Quantitative Determination of Linseed Oil in Mixtures of the Two Oils by Means of the Iodine and Hexabromide Numbers of the Fatty Acids' By Edward A. Tschudy 8,I. DU POXT DE XSMOURS 82 CO.,PHILADELPHIA, PENNSYLVAXIA In a recent paper2 Bailey and Baldsiefen have published This can be shown by substituting in Equation 1 the per results for the quantitative determination of linseed oil in cent of linseed oil present in the mixture and computing the mixtures of linseed and soy-bean oils, by a modified method corrected iodine number, as tabulated. for the determination of the hexabromide number of the fatty R~~~~~~~BETWEEN H~~~~~~~~~~N~~~~ OF THE pAmY acids. It is possible, from the results there enumerated, to ACIDS AND THE PERCENTAGEOF LINSEED show the relation existing between the iodine numbers and the OILIN THE MIXTURES hexabromide numbers of the fatty acids of such mixtures, and to ascertain the error introduced into a determination when BY Plotting the hexabromide numbers of the fatty acids in oils having constants differing from those used by Bailey and Table IV (Bailey and Baldsiefen) against the Per cent of lin- Baldsiefen in their investigation occur in mixtures, the iodine seed-od Present in certain mixtures designated as Samples or hexabromide numbers of which are compared with Tables I11 or IV of their paper to ascertain the percentage of linseed oil present in the mixtures. RELATIONBETWEEN IODINENUMBER AND PERCENTAGEOF ,oo LINSEEDOIL IN MIXTURES By plotting the iodine numbers of the mixtures in Table I11 (Bailey and Baldsiefen) against the per cent of linseed 8o oil (Graph I), the plotted points lie on a straight line, the -. general equation of which is rs X-b -8 60 = 7. s2 For this case, y is the per cent of linseed oil in the mixture, 2 b is the iodine number of the pure soy-bean oil in the mixture, $40 x is the iodine number of the mixture, and m is the cotangent of the angle which the line makes with the x-axis. The io- $ dine numbers of the oils used by Bailey and Baldsiefen in their work have not been recorded, but the linseed oil used probably had an iodine number of 179, and the soy-bean oil an iodine number of 135.5. Substituting these constants in the general equation it becomes 0 30 60 5ro /PO a0 X- 135.5 ~e.?&bI-~?m& i&Jne NQS. (1) = 0.435 ' 793 to 811 (Graph 11))the plotted points lie on a straight line Comparing the calculated values for the per cent of linseed similar to the iodine number-linseed oil curve, and have a oil in the mixtures wit$ the per cent actually present, by similar general equation. For this line y is the per cent of substituting the determined iodine numbers in Equation 1, linseed oil in the mixture, x is the hexabromide number of the we find: fatty acids, b is the hexabromide number of the pure soy-bean --MIXTURE -- oil in the mixture, and m the cotangent of the angle made by Linseed Soy-Bean -Linseed Oil- Oil Oil -Iodine Number- Present Calculated Percentage the line with the x-axis. The linseed oil used by Bailey and Per cent Per cent Determined Corrected Fer cent Per cent Difference Baldsiefen in their mixtures had a hexabromide number of 42, 85 15 171.9 172.5 85 83.8 -1.2 75 25 168.0 168.1 75 74.7 -0.3 while the soy-bean oil had a hexabromide number of 6. Sub- stituting these constants in the general equation it becomes: 5065 35 50 164.2... 157.3163.8 6550 66.1...... The difference between the calculated percentage of linseed X-6 oil in the mixtures and the percentage actually present is very y=- (2) small, and within the limit of experimental error, which, for 0.36 the iodine number, is usually * 0.5 unit. By substituting the determined hexabromide numbers of

1 Received April 18, 1921. the prepared oil mixtures designated Samples 793 to 811 in *TEIS JOURNAL, 12 (1920), 1189. Equation 2, the following results are obtained: