TN 
 
 948 
 
 R3L6 
 
 Idnd 
 
 Tha Radium-Uranium Ratio 
 in Carnotites
 
 THE LIBRARY 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 LOS ANGELES 
 
 The RALPH D. REED LIBRARY 
 
 DEPARTMENT OP fiCTtLOGY 
 
 UNIVERSITY of CALIFORNIA 
 
 LOS AN<;"5l.r^. ' ALIP.
 
 TN 
 
 I 3 
 
 inical Paper 88 Mineral Technology 6 
 
 DEPARTMENT OF THE INTERIOR 
 BUREAU OF MINES 
 
 JOSEPH A, HOLMES, DIRECTOR 
 
 THE RADIUM-URANIUM RATIO 
 IN CARNOTITES 
 
 S. C. LIND AND C. F. WHITTEMORE 
 
 of 
 
 . / - 
 
 SRSITY of C 
 LOS ANGELES, CA 
 
 __ _ . 
 
 PROPERTY OF 
 OGY DEPART* 
 
 LOS ANGELES 
 
 WASHINGTON 
 
 GOVERNMENT PRINTING OFFICE 
 1915
 
 The Bureau of Mines, in carrying out one of the provisions of its organic act to 
 disseminate information concerning investigations made prints a limited free edition 
 of each of its publications. 
 
 When this edition is exhausted copies may be obtained at cost price only through 
 
 the Superintendent of Documents, Government Printing Office, Washington, D. C., 
 
 who is the authorized agent of the Federal Government for the sale of all publications. 
 
 The Superintendent of Documents is not an official of the Bureau of Mines. His is 
 
 an entirely separate office and he should be addressed: 
 
 SUPERINTENDENT OF DOCUMENTS, 
 Government Printing Office, 
 
 Washington, D. C. 
 
 The general law under which publications are distributed prohibits the giving of 
 more than one copy of a publication to one person. Additional copies must be pur- 
 chased from the Superintendent of Documents. The price of this technical paper is 
 5 cents. 
 
 First edition. March, 1915.
 
 Geology 
 Library 
 
 TN 
 
 CONTENTS. 
 
 Introduction i 
 
 Work of other investigators 
 
 Variations of ratio in minerals other than pitchblende 
 
 Constancy of the ratio in pitchblendes 
 
 The ratio in carnotites g 
 
 Description of samples g 
 
 Discussion of methods used 9 
 
 The emanating power of carnotite 10 
 
 Impracticability of solid-ore radiation method for carnotite 12 
 
 Emanation -method for the determination of radium 12 
 
 Solution method 12 
 
 Solution emanation method in a single operation ' 12 
 
 Solution and boiling off emanation 14 
 
 Fusion method 14 
 
 Fusion-and-solution method 15 
 
 Ignition method -. 16 
 
 Electroscopic determination of radium. W 
 
 Electroscope with detachable ionization chamber 17 
 
 Standardization of electroscopes 19 
 
 Data for standard pitchblende 20 
 
 Control of standardization 20 
 
 Procedure in using the electroscope 20 
 
 The determination of uranium 21 
 
 Gravimetric method for vanadium and uranium in carnotite 21 
 
 Separation of alumina 22 
 
 Results of experiments 23 
 
 Discussion of results 26 
 
 Summary 28 
 
 Acknowledgment 28 
 
 Publications on mineral technology 29 
 
 ILLUSTRATIONS. 
 
 PLATE I. A, View of electroscope with interchangeable ionization chambers; 
 B, Ionization chamber detached from instrument and cap in 
 place 
 
 FIGURE 1. Apparatus for determining emanation by sealed-tube method 
 
 2. Apparatus for dissolving carnotite and collecting the emanation 
 
 3. Sulphuric-acid microdrying bulb 
 
 4. Cross section of electroscope with detachable ionization chamber. .. 18
 
 Geology 
 Library 
 
 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 By S. C. LIND and C. F. WHITTEMORE. 
 
 INTRODUCTION . 
 
 One of the recent investigations undertaken by the Bureau of 
 Mines, in pursuance of its endeavors to increase efficiency in the 
 mining and treatment of the mineral resources in the United States, 
 deals with methods of lessening waste in the extraction of radium 
 from the carnotite and other uranium-bearing minerals of Colorado 
 and Utah. In the course of this investigation it has been necessary 
 to study the physical and chemical properties of these ores and to 
 determine the radium and uranium content of many samples. 
 
 The radium-uranium ratio in different uranium minerals has been 
 determined by various investigators, and among such minerals carno- 
 tite has naturally been included, though hi rather surprisingly few 
 instances. The general constancy of the ratios between the quantity 
 of radium and that of uranium hi most uranium minerals may be 
 regarded as definitely established. The bearing of this experiment- 
 ally demonstrated fact on the theory of the source of radium in a 
 series of atomic disintegrations from the parent element uranium 
 needs no comment. 
 
 Although the ratios so determined have been in the main constant 
 and agree well in absolute value with what is to be expected theo- 
 retically from other radioactive measurements, still in some instances 
 there have been rather large deviations and the explanations offered 
 for these must be regarded as only partly satisfactory. The devia- 
 tions have usually been in the direction of low ratios of radium to 
 uranium, though deviations in the opposite direction have also been 
 reported. ; 
 
 In so far as deviations from the normal radium-uranium ratio have 
 been found for carnotite, these hitherto have been invariably low and 
 the impression seems to have become rather general, particularly 
 abroad, that carnotite, as a rule, contains anywhere from a few per 
 cent to 30 per cent less radium than would correspond to its uranium 
 content. It therefore became a matter of some theoretical interest 
 to determine the ratio for a larger number of samples of carnotite 
 than had been investigated. 
 
 1019021
 
 6 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 The determination of the ratio in carnotites has also practical 
 value because of the increasing importance of carnotite as the largest 
 known source of radium. The practice has been and is to buy and 
 sell these ores on the basis of their percentage of uranium oxide 
 (U 3 O 8 ), although European buyers have sometimes insisted on mak- 
 ing allowance for a supposed deficiency in radium. It is evidently of 
 the greatest importance in determining what is the justification for 
 such practice to know within what limits the radium content is fixed 
 by the uranium content. With a view to determining these limits 
 the investigation reported in this paper was undertaken. 
 
 WORK OF OTHER INVESTIGATORS. 
 
 For the first experimental demonstrations of the constancy of the 
 radium-uranium ratio we are indebted to the work of Boltwood/ 1 
 Rutherford, 6 Strutt, c McCoy/ and Eve. 
 
 VARIATIONS OF RATIO IN MINERALS OTHER THAN PITCHBLENDE. 
 
 Later it began to be recognized that certain uranium minerals of 
 secondary origin, of which autunite [Ca(UO 2 ) 2 (PO 4 ) 2 .8H 2 O] is one 
 of the chief representatives, show a radium-uranium ratio below 
 that of pitchblende. In 1909 Mile. Gleditsch-'' announced that she 
 had found a sample of French autunite showing only about 80 per 
 cent of the normal (pitchblende) ratio. A low ratio for autunite was 
 confirmed in 1910 by Russell/ who found, also in a sample of French 
 autunite, a ratio only 27 per cent of the normal; while Soddy and 
 Pirret A about the same time found that the ratio for a sample of 
 Spanish autunite was 44.5 per cent of the pitchblende ratio. 
 
 To account for these low ratios in a sense consistent with the 
 Rutherford and Soddy theory of radioactivity, two different explana- 
 tions have been proposed. One assumes that the secondary minerals 
 are too young for the quantity of radium to have accumulated to the 
 maximum equilibrium value shown hi older minerals such as pitch- 
 blende. The other explanation assumes that the secondary minerals, 
 
 a Boltwood, B. B., The origin of radium: Philos. Mag., vol. 9, 1905, pp. 599-613; On the ratio of radium 
 to uranium in some minerals: Am. Jour. Sci., ser. 4, vol. 18, 1904, pp. 97-103; On the radioactivity of ura- 
 nium minerals: Am. Jour. Sci., ser. 4, vol. 25, 1908, pp. 269-298. 
 
 6 Rutherford, E. E., and Boltwood, B. B., The relative proportion of radium and uranium in radioactive 
 minerals: Am. Jour. Sci., ser. 4, vol. 20, 1905, pp. 55-56; vol. 22, 1906, pp. 1-30. 
 
 cStrutt, R. J., On the radioactive minerals: Proc. Roy. Soc. London, ser. A, vol. 76, 1905, pp. 88-101; 
 Note supplementary to paper, vol. 76, p. 312. 
 
 d McCoy, H. N., Ueber das Entstehen des Radiums: Ber. Deutsch. chem. Gesell., Jahrg. 37, Bd. 4, 
 1904, pp. 2641-2656; Radioactivity as an atomic property: Jour. Am. Chem. Soc., vol. 27, pt. 1, 1905, p. 391. 
 
 e Eve, A. 8., The measurement of radium in minerals by the r-radiation: Am. Jour. Sci., ser. 4, vol. 22, 
 1906, pp. 4-7. 
 
 / Gleditsch, Ellen, Sur le radium et 1'uranium contenus dans les mine'raux radioactifs: Compt. rend., 
 1. 148, 1909, p. 1451; Sur le rapport entre 1'uranium et le radium dans les mhuJraux radioactifs: 1. 149, 
 1909, p. 267. 
 
 e Russell, A. S., The ratio between radium and uranium in minerals: Nature, vol. 84, 1910, pp. 238-239. 
 
 Soddy, Frederick, and Pirret, Ruth, The ratio between radium and uranium in minerals: Philos. Mag., 
 voL 20, 1910, pp. 345-349; vol. 21, 1911, pp. 652-658.
 
 WORK OF OTHER INVESTIGATORS. 7 
 
 because of a looser mechanical structure, are more easily leached by 
 water and that radium is more readily removed than uranium, so that 
 the ratio of radium to uranium is diminished by this process. 
 
 Additional evidence adduced principally by Marckwald and Rus- 
 sell a appears to support the leaching theory, for in autunite the 
 ionium-uranium ratio was found to approach the theoretical value 
 much more nearly than does the radium-uranium ratio, thus indicat- 
 ing a removal of radium, whereas lead, one of the end products of 
 the uranium family, was found to be almost entirely lacking. 
 
 At the same time that Mile. Gleditsch b announced the existence 
 of a low radium-uranium ratio in autunite she reported a high ratio 
 (about 16 per cent high) in thorianite from Ceylon. Explaining a 
 high ratio appeared to present much more formidable difficulties than 
 explaining low ones. Mile. Gleditsch favored the view that either 
 ionium or some unknown member between uranium and radium had 
 a much longer period than was previously supposed, necessitating 
 a greater lapse of time for the attainment of equilibrium. Conse- 
 quently, according to this view, all the uranium minerals would be 
 slowly advancing to an equilibrium content of radium higher than 
 that in most pitchblendes. 
 
 The view held by Mile. Gleditsch did not find general acceptance. 
 Soddy and Pirret c had also examined autunite, pitchblende, and 
 thorianite, and, although confirming a low ratio for autunite, as 
 already stated, they failed to find a difference between the latter 
 two exceeding 3 per cent, which they regarded as within their limits 
 of experimental error. 
 
 In a later investigation extended to a much larger number of 
 uranium minerals Mile. Gleditsch d confirmed her earlier results, find- 
 ing ratios of radium to uranium varying from 1.82 X 10~ 7 for chalcolite 
 from Saxony to 3.74 XlO~ 7 for pitchblende from Cornwall; whereas 
 for two pitchblendes from Norway she reported 3.48 X 10~ 7 and 
 3.64 X 10~ 7 , respectively. 
 
 CONSTANCY OF THE RATIO IN PITCHBLENDES. 
 
 The most recent experimental contribution to the subject is the 
 searching examination by Heimann and Marckwald of the radium- 
 uranium ratio in eight samples of pitchblende from all the principal 
 pitchblende localities of the world, including Joachimsthal, Saxony, 
 
 a Marckwald, W., and Russell, A. S., tJber den Radiumgehalt einiger Uranerze: Her. Deutsch. chem. 
 Gesell., Jahrg. 44, Bd. 1, 1911, pp. 771-775; Uber den Radiumgehalt von Uranerzen: Jahrb. Radtoakt. 
 Elektronik, Bd. 8, 1911, p. 457. 
 
 6 Gleditsch, Ellen, loc.cit. 
 
 c Soddy, Frederic, and Pirret, Ruth, loc. cit. 
 
 d Gleditsch, Ellen, Sur le rapport entre P uranium et le radium dans les mineraux actlB: L Ki ium , 
 
 Vnetaann, Berta, and Marckwald, W., Uber den Radiumgehalt von Pechblenden: Physlk. Ztechr., 
 Jahrg. 14, 1913, pp. 303-305; Jahrb. Radioakt. Elektronik, Bd. 10, 1913, p. 299.
 
 8 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 German East Africa, Norway, Bohemia, Colorado, and Cornwall. 
 Determinations were made by two entirely different methods the 
 emanation method and the gamma-ray method. For all eight sam- 
 ples the ratio was found to be constant within 0.4 per cent. The 
 absolute value of the ratio was determined by comparison with a 
 radium solution having its origin in the Honigschmid atomic- 
 weight radium of the Institute for Kadium Eesearch in Vienna, and 
 was found to be 3.328 X 10~ 7 . The satisfactory agreement of this 
 number with the theoretical value of the ratio as calculated from 
 radiation data 6 lend it additional reliability. 
 
 THE RATIO IN CARNOTITES. 
 
 As already stated, a few investigators have included carnotites 
 among the uranium minerals they examined. The results of Bolt- 
 wood c and of McCoy d show no abnormally low ratio for this mineral. 
 Mile. Gleditsch e reported for a sample of Colorado carnotite a ratio 
 of only 2.34 X 10~ 7 , which corresponds to about 70 per cent of the 
 normal ratio. Marckwald and Russell -^ found that the ratio was 
 91.6 per cent of normal ratio for a carnotite from Colorado and 71.5 
 per cent for one from Florida (?).^ The impression seems to have 
 been general, probably because of these results, that carnotite always 
 has a low ratio. 
 
 By way of anticipation, the authors of this paper state here that 
 with small samples they have sometimes confirmed the low ratios, 
 finding one almost as low as that found by Mile. Gleditsch, which, 
 however, is to be regarded as exceptional. On the other hand, the 
 authors have also found an equal number of high ratios Qikewise 
 in small samples only), some as high as the highest ratios found by 
 Mile. Gleditsch for any of the primary minerals and one considerably 
 higher, 4.6X10" 7 , which is the highest ratio yet reported for any 
 uranium mineral. 
 
 What appears to the authors to be of the greatest significance is 
 the fact that these abnormal ratios, both high and low, occur only in 
 samples representing small quantities (a few pounds) of ore; whereas 
 
 a Honigschmid, O., Revision des Atomgewichtes des Radiums und Herstellung von Radiumstandard- 
 praparaten: Sitzb. K. Akad. Wiss., Abt. 2-a, Bd. 120, 1911, pp. 1617-1652. 
 
 6 See calculation by Meyer, Stefan, liber die Lebensdauer von Uran und Radium: Sitzb. K. Akad 
 Wiss., Abt. 2-a, Bd. 122, June, 1913, p. 1085. 
 
 c Boltwood, B. B., On the ratio of radium to uranium in some minerals: Am. Jour. Sci., ser. 4, vol. 
 18, 1904, pp. 97-103; On the radioactivity of uranium minerals: vol. 25, 1908, pp. 269-298. 
 
 <J McCoy, H. N., Ueber das Entstehen des Radiums: Ber. Deutsch. chem. Gesell., Jahrg. 37, Bd. 3, 
 1904, pp. 2641-2656; Radioactivity as an atomic property: Jour. Am. Chem. Soc., vol. 27, pt. 1, 1905, p. 
 391. 
 
 Gleditsch, Ellen, Sur le rapport entre 1'uranium et le radium dans les mine'raux actifs: Le Radium, 
 t. 8, 1911, pp. 256-273. 
 
 / Marckwald, W., and Russell, A. S., Uber den Radiumgehalt einiger Uranerze: Ber. Deutsch. chem. 
 Gesell., Jahrg. 44, Bd 1, 1911, p. 771; tiber den Radiumgehalt von Uranerzen: Jahrb. Radioakt. Elek- 
 tronik, Bd. 8, 1911, p. 457. 
 
 e The authors of this paper have not been able to verify the occurrence of carnotite in Florida.
 
 DISCUSSION OF METHODS USED. 9 
 
 all samples from large lots (one ton to a carload) invariably show a 
 ratio practically identical with that of pitchblende. This relation 
 seems to suggest strongly a possible transposition of radium within 
 the ore body rather than one of complete removal by leaching. The 
 point is more fully discussed on a later page (pp. 26-27) ; but evidently 
 there is no reason to suppose an abnormal ratio in carnotite provided 
 the determination be made on a sample representative of a consid- 
 erable portion of an ore body, whereas if the quantity of ore repre- 
 sented by the sample be small, the result may be either too high or 
 too low. 
 
 DESCRIPTION OF SAMPLES. 
 
 The samples of carnotite investigated were chosen with the object of 
 their representing the carnotite of all the principal localities in Col- 
 orado and Utah where the mineral has been found in important 
 quantities. All grades of carnotite containing 1.5 to 33 per cent of 
 U 3 O 8 have been included. 
 
 The samples were not collected by the authors, nor were they 
 taken with any reference to geological conditions or position in ore 
 beds ; they simply represent carnotites that come on the market either 
 as specimens or in commercial quantities. As already mentioned, 
 a special significance attaches to the specimens representing large 
 quantities of ore. Owing to the large output of carnotite ore hi 1913 
 the authors fortunately were able to obtain "pulp" samples repre- 
 senting large quantities of carefully sampled ore, which the authors 
 believe to be of the utmost importance in obtaining the true content 
 of radium. The samples analyzed were supplied through the cour- 
 tesy of Messrs. W. L. Cummings, Thomas F. V. Curran, Gordon 
 Kimball, W. L. Meyer, David Taylor, and the National Radium 
 Institute. 
 
 DISCUSSION OF METHODS USED. 
 
 Two distinct determinations enter into the radium-uranium ratio 
 which affect equally the accuracy of the result. The measurement 
 of radium in carnotite, as in other ores, is most readily accomplished 
 by the emanation method, which consists in the liberation by any 
 suitable method of the radium emanation corresponding to the radium 
 in the ore, the quantity of emanation and of radium being ascertained 
 by using an electroscope with a gas-tight ionization chamber. The ema- 
 nation method may be employed after the ore has been prepared by 
 either of two methods: (a) The ore is kept in a closed vessel for a 
 month or more until it has attained its maximum equilibrium quan- 
 tity of emanation; or (&) the emanation is initially reduced to zero 
 and subsequently allowed to accumulate in a closed vessel for a 
 known period (usually several days), the maximum amount and 
 67885 15 2
 
 10 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 hence tne radium content being then calculated by means of the Kolo- 
 wrat tables.* Only the former or "equilibrium" method was em- 
 ployed for final values in the radium determinations reported in 
 this paper. Results obtained by the accumulation method are re- 
 ported on page 17 as being unsatisfactory. 
 
 Aluminum leaf electroscopes of the Wilson type, with ionization 
 chamber and leaf system separate were used. A full description of 
 the electroscopes and the manipulative details will be found on sub- 
 sequent pages. The instruments were calibrated by means of 
 analyzed pitchblende from Colorado, the ratio found by Heimann 
 and Marckwald 6 of 3.328 XlCT 7 being assumed to be correct. 
 
 The determination of uranium in carnotite presents especial diffi- 
 culties because of the presence of vanadium, and many of the earlier 
 proposed methods of separating the two metals have proved un- 
 suitable. A full description of the method used by Ledoux & Co., 
 which the authors of this paper found satisfactory, is given on pages 
 21 and 22, as well as references to other methods that were sometimes 
 employed for control. 
 
 The small quantity of uranium hi most carnotites as compared 
 with that in higher-grade ores renders difficult the attaining of the 
 desired degree of accuracy in determining the uranium, and to a 
 less degree the radium content. The authors sought to overcome 
 this difficulty by repeating determinations frequently and by employ- 
 ing additional methods of control in all cases of doubt. All radium 
 determinations have been checked by at least two independent 
 methods of liberating the emanation. The average results reported 
 on pages 23 to 26 are believed to be accurate within 1 to 2 per cent. 
 
 THE EMANATING POWER OF CARNOTITE. 
 
 The term "emanating power" was first used by Boltwood c to 
 signify the percentage loss of emanation from a radioactive substance, 
 and in the determination of radium it was applied by him as an additive 
 correction to the quantity of emanation liberated by direct solution. 
 Such a correction is of especial importance in determining radium in 
 carnotites in which the authors have found the emanating power to 
 be high, from 16 to 50 per cent (see Table 1). This high emanating 
 power, which is one of the distinguishing characteristics of carnotite, 
 was a controlling factor in the experimental procedure, hence it is 
 discussed somewhat fully here. 
 
 a Kolowrat, Le"on. Le Radium, t. 6, 1909, p. 194. Also given in most treatises on radioactivity. 
 Heimann, Berta, and Markwald, W., Tiber den Radiumgehalt von Pechblenden: Physik. ztschr., 
 Jahrg. 14, 1913, p. 303; Jahrb. Radioakt. Electronik, Bd. 10, 1913, p. 299. 
 
 c Boltwood, B. B., The origin of radium: Philos. Mag., vol. 9, 1905, pp. 599-613.
 
 THE EMANATING POWER OF CAENOTITE. H 
 
 The loss of emanation by the ore is due to diffusion of the gas and 
 is much lower (only 3 to 8 per cent) for dense, compact minerals 
 like pitchblende than for carnotites, which have a looser mechanical 
 structure. For a given sample the loss is doubtless, as suggested by 
 Rutherford, dependent on the degree of fineness to which the ore 
 is pulverized. The authors of this paper have not undertaken any 
 direct investigation of the relation between emanating power and 
 fineness or any other property, but have ascertained that among 
 different specimens fineness can not be the principal controlling 
 factor, for there seems to be no relation whatever between the order 
 of fineness of different samples and their emanating power. 
 
 Evidently a given percentage error in determining the emanating 
 power to be used additively in obtaining the total emanation by 
 Boltwood's method would more seriously affect the final result in 
 the case of a carnotite than in that of an ore for which the relative 
 value of the emanating power is small. 
 
 Repetition by the writers of this paper, of earlier determinations made 
 by them, showed considerable variation in emanating power, which sug- 
 gested that the emanation was not always removed to the same degree 
 from the same sample. This variation is probably caused by dif- 
 ferences in the volume of air passed over the ore, or to differences in 
 pressure or velocity of the air, and the consequent drawing of varying 
 amounts of emanation out of the more or less porous structure. As 
 a remedy the authors used a simple modification of the Boltwood 
 method, namely, making the determination of the emanating power 
 and the emanation liberated by solution strictly " complementary" 
 to each other in the sense that each sample dissolved should repre- 
 sent part or all of the sample from which emanation had just been 
 drawn to determine the emanating power. By this procedure it does 
 not matter whether corresponding determinations of emanating 
 power are concordant or not, so long as the sums obtained by adding 
 corresponding determinations are in agreement. That this assump- 
 tion is correct may be seen from the following table, which shows that 
 for each ore the agreement for the total emanation is better than that 
 of either of the individual values going to make up the sum. Only 
 a few examples illustrative of this point are given because it was 
 found more convenient to determine the total emanation in one 
 operation, as described later. In this and other tables each ore is 
 designated by the same number throughout. 
 
 a Rutherford, E. E., Radioactive substances and their radiations, 1913, p. 364.
 
 12 THE RADIUM-UBANIUM EATIO IN CARNOTITES. 
 
 Table illustrating advantage of "complementary" emanation method. 
 
 
 
 
 Total a 
 
 
 Emana- 
 
 Solution 
 
 emana- 
 
 Number of ore. 
 
 ting 
 power, 
 curiesx 
 
 emana- 
 tion, 
 curies X 
 
 tion per 
 gram of 
 ore, 
 curieslx 
 
 2 
 
 / 15.0 
 \ 17.6 
 
 87.1 
 84.5 
 
 102.1 
 102.1 
 
 4 
 
 / 14.0 
 
 58.6 
 
 72.6 
 
 5 
 
 \ 11.7 
 / 21.8 
 
 27.7 
 
 49.5 
 
 
 \ 23.6 
 
 26.2 
 
 49.8 
 
 
 / 4.38 
 
 8.93 
 
 13.3 
 
 
 ( 4.45 
 
 8.50 
 
 13.0 
 
 a Each value 
 columns. 
 
 this column is the sum of the two values, on the same line, in the two preceding 
 
 IMPRACTICABILITY OF SOLID-ORE RADIATION METHOD FOR CARNOTITE. 
 
 It should also be noted in discussing emanating power that the 
 high and variable values exhibited by carnotite seem to preclude 
 the possibility of employing for accurate determination any radiation 
 method from the solid ore for either the alpha, the beta, or the 
 gamma rays unless, in the employment of the gamma-ray method, a 
 large quantity of ore could be kept for a month, and later measured, 
 in an absolutely tight vessel. 
 
 EMANATION METHOD FOB THE DETERMINATION OF RADIUM. 
 
 For the liberation of emanation from carnotite the authors origi- 
 nally planned to use three methods: (a) Solution method boiling 
 in 1: 1 HNO 3 solution; (6) fusion method fusing with a mixture of 
 and KjCOg; (c) fusion and solution method fusing with 
 and K 2 CO 3 , followed by solution in 5 per cent Na^COg solu- 
 tion, filtration, solution of the residue in 1 : 3 HNO 3 solution, and 
 separate treatment of both solutions. The failure of methods & and 
 c to give satisfactory results (see table on p. 17) led to the use of a 
 fourth, (d) ignition method without flux. A description of the de- 
 tails of these methods is given in the following paragraphs. 
 
 SOLUTION METHOD. 
 
 The solution method may be used as described (p. 11) by adding the 
 "emanating power" to the "solution emanation." In this procedure 
 the authors found it advisable to modify the Boltwood method by 
 making the two determinations, complementary to each other, as 
 already stated. 
 
 SOLUTION EMANATION METHOD IN A SINGLE OPERATION. 
 
 Unless one desires to know the emanating power itself it is simpler 
 to determine the total emanation in one operation by sealing the ore 
 hi a very thin bulb, of the type shown in figure 1, for a month or 
 more before breaking under acid to liberate the total emanation.
 
 fTO GAS 
 1 BURETTE 
 
 EMANATION METHOD FOR DETERMINATION OF RADIUM. 13 
 
 The bulb a, of 4 to 10 mm. diameter, according to the quantity of 
 ore to be used, is blown very thin so as to break without endangering 
 the outer flask /, contain- 
 ing .HNO 3 . The ore is 
 weighed into the bulb 
 through I and then the 
 glass stem c is sealed on 
 and is constricted to make 
 a complete seal at d, the 
 upper end e being also 
 sealed for convenience. 
 The whole is introduced 
 
 through a double - bored 
 rubber stopper to a point 
 just off the bottom of the 
 flask / and may be broken 
 by a slight downward rap 
 on e. By boiling the acid, 
 the ore is -readily attacked 
 and all of the emanation 
 is boiled over into a gas 
 burette (see fig. 2). 
 
 The results obtained with this method check excellently with the 
 results of the "complementary" modified Boltwood method as can 
 be seen from the following table: 
 
 Results of sealed bulb method for total emanation in one operation, compared with com- 
 plementary method. 
 
 CARNOTITE 
 
 FIQTJBE 1. Apparatus for determining emanation by sealed- 
 tube method. 
 
 Number 
 of ore. 
 
 Method used. 
 
 Emanating 
 power, 
 curiesX10. 
 
 Solution 
 emanation, 
 ciiriesXlO". 
 
 Total ema- 
 nation per 
 gram of ore, 
 curiesXlO*. 
 
 
 [Sealed bulb 
 
 
 
 11.09 
 
 
 \Complementary 
 
 / Sealed bulb 
 
 3.906 
 
 7.188 
 
 11.09 
 8.08 
 
 
 \Complementafy 
 /Sealed bulb 
 
 3.488 
 
 4.467 
 
 "7.96 
 7 08 
 
 16 
 
 
 3.191 
 
 3.916 
 
 o7.ll 
 
 
 /Sealed bulb 
 
 
 
 7.34 
 
 18 
 
 
 1.224 
 
 6.156 
 
 o7.38 
 
 
 /Sealed bulb 
 
 
 
 a 54 
 
 
 \Complementary 
 
 2.993 
 
 5.606 
 
 08.60 
 
 
 /Sealed bulb 
 
 
 
 29.91 
 
 20 
 
 
 9.847 
 
 19.77 
 
 a29.62 
 
 
 /Sealed bulb 
 
 
 
 23.61 
 
 21 
 
 
 10.72 
 
 13.12 
 
 * 
 
 
 /Sealed bulb 
 
 
 
 21.21 
 
 22 
 
 
 3.445 
 
 17.64 
 
 021.09 
 
 
 P 7 
 
 
 
 
 i Sum of results given, on same line, in the two preceding columns.
 
 14 
 
 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 k 
 
 SOLUTION AND BOILING OFF EMANATION. 
 
 The method of solution and boiling off the emanation requires no 
 especial explanation. The apparatus is shown in figure 2. 
 
 Hot water containing some NaOH is used in the gas burette Tc; 
 1 :1 HNO 3 solution is used as a solvent of the carnotite. A glass stop- 
 cock at s is more convenient than rubber tubing and a clamp. All 
 possibility of loss of emanation by the passage of water into the side 
 arm t is avoided by allowing all air to pass up into Tc before the bulb a 
 is broken. In case an ore is not sealed in glass, the same result may 
 be accomplished by placing the ore in a 
 filter paper and folding the paper so that 
 it remains in the neck of the flask / until 
 all air is expelled and the steam softens 
 the paper, allowing it and its contents to 
 drop into the acid. The stopcock should 
 be closed at this time (or on breaking the 
 glass bulb) and then gradually opened to 
 prevent a sudden rush of gas from carry- 
 ing undissolved ore up into the alkaline 
 solution. 
 
 Pitchblende used for standardization 
 purposes was treated in the same way as 
 carnotite, either directly with correction 
 for emanating power, or from a glass tube 
 that had been sealed for one month. 
 
 FUSION METHOD. 
 
 The great advantage of ' ' accumulation " 
 over "equilibrium" emanation methods 
 requiring a month, led the authors to 
 attempt to employ a fusion method, since 
 accumulation in solution is well known to 
 give low results because of the removal of 
 radium by precipitation or by adsorption. The method employed is 
 as follows: 
 
 'A quantity of ore sufficient to furnish enough emanation to produce 
 a discharge of about one scale division per second, is thoroughly fused 
 over a Meker burner in a platinum boat or dish with five or more 
 times its weight of a mixture of one part Na 2 CO 3 to one part K 2 CO 3 , 
 enough tune being allowed during fusion for all emanation to be 
 driven off from the fused mass. The tune of solidification is noted 
 as the zero point for the accumulation of emanation and the fusion 
 is set aside in a desiccator for three or four days; it is not necessary 
 to keep the fused mass in a sealed vessel during accumulation, as a 
 special experiment showed that there is no emanation loss from the 
 
 FIGURE 2. Apparatus for dissolving 
 carnotite and collecting the emana- 
 tion.
 
 EMANATION METHOD FOR DETERMINATION OF RADIUM. 15 
 
 cold fusion. The second fusion to liberate emanation may be made 
 either in the platinum boat in which the first was made by inserting 
 the boat into a silica tube with ground glass joints as proposed by 
 Ebler, a or better still, to attain a higher temperature the fusion is 
 removed from the boat or dish and inserted into Jena combustion 
 tubing of suitable diameter, in which it is held in place by glass wool 
 plugs that, reacting with the flux, furnish a vigorous evolution of car- 
 bon dioxide to assist in the removal of emanation. The heating is 
 accomplished by means of a Meker burner and is continued until the 
 Jena glass completely collapses. A higher temperature is obtained 
 in the bare Jena glass than in a platinum boat inside a silica tube, 
 but on the other hand one loses the advantage of being able to repeat 
 the fusion any number of tunes after renewed accumulation. 
 
 In spite of its great promise and actual success hi experiments with 
 pitchblende and crude sulphates, the fusion method has proved a 
 failure for carnotite, even for high-grade ore requiring only a small 
 quantity of flux, as will be seen in the table on page 17. If a 
 higher temperature, by electric heating, were used the method 
 might yield correct results, but such heating was not tried because 
 of the same end being attained more readily by the method of igni- 
 tion without flux. Two general precautions should be mentioned 
 here: (1) The gases, should be allowed to stand in a gas burette for 
 about 10 minutes to permit the decay of thorium emanation before 
 they pass into the emanation chamber. As no evidence has 
 been obtained of the presence of thorium in carnotite this precaution 
 may be omitted. (2) In case of a large evolution of carbon dioxide 
 from the fusion in glass, a potash bulb should be inserted in front of 
 the drying bulb to prevent carbon dioxide from entering the ioniza- 
 tion chamber; otherwise, the fact that the "specific ionization" of 
 carbon dioxide is greater than that of air makes the results obtained 
 too high. 
 
 FUSION-AND-SOLUTION METHOD. 
 
 Fuse the ore with a mixture of Na 2 CO 3 and K 2 CO 8 as described 
 for the fusion method, dissolve in a 5 per cent Na-jCOg solution, filter, 
 dissolve the residue in 1 : 3 HNO 3 solution, and remove the emanation 
 from both the acid and alkaline solutions by passage of air for at 
 least 10 minutes. Place each solution in a Jena flask and seal with 
 a rubber stopper fitted with a glass tube having the upper end drawn 
 out to a capillary point. After an accumulation period of several 
 days the glass tube is connected with the collector by a piece of 
 rubber tubing, and the point of the glass tube is broken inside the 
 rubber tubing before boiling off the emanation, as described for solu- 
 tion method. 
 
 a Ebler, Erich, ttber die Bestimmung dos Radiums in Mineralien und Gestelnen: Ztachr. Elektro- 
 chem., Bd. 18, 1912, p. 532.
 
 16 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 As shown by the table on page 17, the fusion-and-solution method 
 gives results 10 to 20 per cent low, doubtless because of the adsorp- 
 tion of radium or radium emanation in the colloidal silica which almost 
 invariably appears in the carbonate and sometimes in the acid solution 
 also, even after refiltering once or twice. The method appears to 
 give better results with substances containing little or no silica, but 
 for those the simple direct-fusion method is also applicable. The 
 carbonate solution usually filters very slowly, and on the whole the 
 authors do not recommend the fusion-and solution method as being 
 either accurate or convenient for carnotites. 
 
 IGNITION METHOD. 
 
 The application of the ignition method to carnQtite was suggested 
 by the ease with which the ore itself liberates its emanation even in 
 the cold, whereas the cold fusion loses none. 
 Should such a difference persist at higher tem- 
 peratures, ignition without flux would appear 
 preferable. In fact, this method has been found 
 entirely satisfactory. 
 
 To hold the ore, straight pieces of Jena combus- 
 tion tubing, about 4 to 10 mm. internal diameter, 
 depending on the volume of the sample, and about 
 15 to 20 cm. long, were used. One end of a tube 
 was drawn to a point and the weighed ore was 
 introduced through the open end, which was then 
 drawn out and sealed. Glass wool plugs were used 
 to hold the ore in place in the middle of the tube. 
 After standing one month or more the tube was 
 connected by means of sulphuric-acid microdrying 
 bulbs (fig. 3) to the exhausted electroscope on one 
 FIGUBE 3 sulphuric- s ^ e an( ^ ^ ^ ne outside air on the other side. After 
 acid microdrying buib. the capillary ends inside the rubber connections 
 were broken air was allowed to pass over the ore into the electroscope, 
 the tube being heated over a Meker burner 1J inches in diameter 
 until the Jena glass completely collapsed. This treatment, as the 
 following table shows, gives complete de-emanation. 
 
 Air was passed directly over the ore through a drying bulb into the 
 electroscope a procedure that is justified only when thorium is ab- 
 sent. That the ore contained no thorium is supported by two experi- 
 mental observations first, that the electroscope, after the radium 
 emanation is pumped out, returns in a few hours to its normal natural 
 leak, whereas it would not do so if contaminated by active deposit of 
 thorium emanation; and, second, the results obtained by the ignition 
 method agree well with those obtained by the solution method, in
 
 ELECTEOSCOPIC DETERMINATION OP RADIUM. 
 
 17 
 
 which the emanation was always permitted to stand in a gas burette 
 for 10 minutes before being passed into the emanation chamber. It 
 seems certain, then, that there is little or no thorium in carnotites. 
 In the following table is a comparison of results obtained for a 
 number of carnotite ores by using the four methods just described. 
 Examination of these results shows that the solution method and the 
 ignition method give concordant results, whereas the fusion method 
 and the fusion-and-solution method give low results. For this reason 
 the two latter methods were not employed in obtaining any of the 
 data reported in Table I. 
 
 Comparison of results of different methods for de-emanating carnotites. 
 
 Number 
 of ore. 
 
 Total emanation in curies X 10 by method of 
 
 Solution in 
 1:1HNO 8 . 
 
 Fusion 
 with 
 NauCOa 
 andKjCO 8 . 
 
 Ignition. 
 
 Fusion 
 and 
 solution. 
 
 2 
 
 4 
 
 101.4 
 72.6 
 7.83 
 11.09 
 8.08 
 7.11 
 8.66 
 
 63.5 
 
 98.0 
 73.3 
 7.89 
 11.63 
 
 83.0 
 53.8 
 6.20 
 8.92 
 6.98 
 
 13 
 
 2.62 
 
 14 
 15 
 
 16 
 17 
 
 
 7.17 
 8.65 
 
 7.38 
 
 ELECTROSCOPIC DETERMINATION OP RADIUM. 
 
 Two electroscopes were employed in making determinations, both 
 being of the Wilson type, with sulphur insulation in the neck sepa- 
 rating the ionization chamber from the leaf system. One of the 
 electroscopes a had a chamber of 1 liter capacity. The other electro- 
 scope differed only in having a cylindrical ionization chamber of 
 about i-Hter capacity. 
 
 This type of instrument has several advantages over that with the 
 leaf system contained in the ionization chamber. The charging 
 device is simpler and can always be brought back to a definite 
 position, thus avoiding the danger of a variable electrical capacity. 
 A charge can also be easily maintained for any desired time during the 
 formation of induced activity, something that can not be conveniently 
 done with instruments having a suspended charging rod controlled by 
 a magnet. 
 
 ELECTROSCOPE WITH DETACHABLE IONIZATION CHAMBER. 
 
 A new type of electroscope has recently been devised by one of 
 the authors to facilitate making a large number of radium deter- 
 minations daily at a minimum expense for instruments. 
 
 For a description and view of this electroscope see Moore, R. B., and Kithil, K. L., A preliminary 
 report on uranium, radium, and vanadium: Bull. 70, Bureau of Mines, 1914, p. 66.
 
 18 
 
 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 The new electroscope (fig. 4 and PI. I, A and B) has an ionization 
 chamber a (fig. 4), detachable from an upper cage 6, containing the 
 leaf system and microscope. By this device any number of ioniza- 
 tion chambers may be used with one electroscope, thus avoiding 
 duplication of the more expensive and delicate parts of the instru- 
 ment. The advantages are obvious if one considers that in an ordi- 
 nary emanation electroscope only one determination can be made 
 daily, whereas in the detachable form as many may be made as one 
 has ionization chambers. An ionization chamber costs about one- 
 tenth as much as the complete instrument, hence an equipment 
 
 equivalent in use to 10 electroscopes 
 may be had for the cost of two. 
 
 The ionization chamber may be of 
 any form or size. For emanation 
 determinations a cylinder of the type 
 shown in figure 4 is recommended. 
 A cylindrical electrode e is insulated 
 from the chamber by means of the 
 best quality of "bankers' " or " spe- 
 cie" sealing wax d, which also serves 
 to make the vessel gas tight. The 
 sealing wax is set in a brass collar 
 that screws into the top of the ioni- 
 zation chamber onto a lead washer 
 and can be readily removed when 
 one desires to renew the insulation 
 or examine its tightness. The elec- 
 trode terminates outside the cham- 
 ber in a small conical brass tip c, 
 serving to make electrical contact 
 with a spring s. When the upper 
 part of the instrument is removed it 
 is replaced with a friction cap of 
 brass (PI. I, B) to protect the electrode tip and sealing wax insula- 
 tion from contamination. To the brass outlet tubes o o (fig. 4) 
 glass stopcocks are attached by means of heavy rubber tubing 
 securely wired on to insure a gas-tight joint. In all other respects the 
 ionization chamber is similar to the older forms. 
 
 The upper part of the instrument consists of a cage 6 (fig. 4), of 
 the usual form, housing the leaf system and, in this case, also acting 
 as a support for the microscope. The leaf system/ is suspended from 
 the top of the cage instead of projecting up from the bottom. The 
 rod to which the leaf is attached is set by means of sealing wax 
 insulation into a brass cap g, which screws into the top of the cage 
 from the outside and can be readily removed for the replacement of the 
 
 FIGURE 4. Cross section of electroscope with 
 detachable ionization chamber (one- third size) .
 
 BUREAU OF MINES 
 
 TECHNICAL PAPER 88 PLATE I 
 
 A. ELECTROSCOPE WITH INTERCHANGEABLE IONIZA- 
 TION CHAMBERS. THE ELECTRIC-LIGHT SOCKET AND 
 WIRE ABOVE THE INSTRUMENT ARE NOT PART OF IT. 
 
 IONIZATION CHAMBER DETACHED FROM INSTRU- 
 MENT AND CAP IN PLACE.
 
 ELECTROSCOPIC DETERMINATION OF RADIUM. 19 
 
 aluminum leaf. If the cap shows any tendency to change position 
 it should be set with a drop of solder to prevent disturbance of the 
 calibration. At the bottom of the leaf support is a light brass 
 spring s, serving to make electrical contact with the conical point c 
 of the electrode of the ionization chamber. The spring should press 
 lightly against the tip, enough to insure firm contact, but not so hard 
 as to displace the leaf system from its normal position when the cage 
 & is set down >n the ionization chamber a. 
 
 One of the advantages of this electroscope is that the microscope, 
 being attached directly and firmly to the leaf chamber (see PI. I, A), 
 can not become displaced relative to the leaf. The miscroscope is 
 held in position by a heavy brass collar set in a vertical plate which 
 is parallel to the front of the leaf chamber and is supported at a dis- 
 tance of about 1 inch from it by three supports screwed into the 
 outside of the cage & (fig. 4). 
 
 The charging device fc, of a simple and efficient type, is insulated 
 from the cage by an ebonite plug n, which screws into the wall of 
 the cage. The core of the plug is also threaded to accommodate 
 the charging rod and to hold it firmly. 
 
 Other types of discharge chambers besides that for emanation 
 may be employed, for example, an open chamber for solids, such as is 
 used in the cursory examination of radioactive ores, or a large water 
 chamber of the fontactometer type as used in determining the radio- 
 activity of waters. 
 
 The purpose in designing this electroscope was to furnish a simple 
 and inexpensive type of instrument, all the parts of which, except the 
 microscope, can be made by any instrument maker or good mechanic. 
 The design also permits of the replacement of any part without dis- 
 turbing the rest of the electroscope. A detailed description of the 
 instrument will be found in the May, 1915, issue of the Journal of 
 Industrial and Engineering Chemistry. 
 
 STANDARDIZATION OF ELECTROSCOPES. 
 
 Standardization of electroscopes was carried out by dissolving about 
 40 milligrams of carefully analyzed pitchblende (see ore No. 12, p. 24) 
 from Colorado in boiling 1 : 1 HNO 3 solution according to the procedure 
 described for carnotites on page 14. The radium content was 
 assumed to be that corresponding to Heimann and Marckwald's 
 ratio of 3.328 XlCT 7 . The pitchblende was analyzed by the method 
 given for carnotite on page 21, omitting the procedure for the separa- 
 tion of vanadium. A number of shorter methods for determining 
 uranium in pitchblende were found unreliable. 
 
 a Heimann, Berta, and Marckwald, W., Uber den Radiumgehalt von Pechblenden: Jahrb. Radioakt 
 Electronik, Bd. 10, 1913, p. 299; Physik. Ztschr., Bd. 14, 1913, p. 303.
 
 20 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 DATA FOR STANDARD PITCHBLENDE. 
 
 One gram of standard pitchblende contains 0.765 gram U 3 O 8 or 
 0.649 gram U, and 2.16X10" 7 gram of radium. The emanating 
 power is 2.7 per cent. Therefore, 1 milligram dissolved directly gives 
 2.10X" 10 curies of radium emanation. 
 
 CONTROL OF STANDARDIZATION. 
 
 A convenient and time-saving procedure for control of the stand- 
 ardization of electroscopes, after careful determinations and checking, 
 was to measure the discharge produced by the penetrating radiation 
 from about 1 milligram of radium, the element being in the form of 
 bromide, in a small sealed glass tube. Another glass tube, large enough 
 to accommodate the radium tube, was fixed in a vertical position in 
 the wooden base of the electroscope at a distance such as to produce 
 a discharge at the rate of about 1 division per second. This measure- 
 ment was repeated every day, as was measurement of natural leak, 
 before using the instrument. For variations of a few per cent 
 attributable to fluctuations of temperature and atmospheric pressure, 
 a correction was made. Greater variations were ascribed to changes 
 in the leaf system necessitating recalibration, but recalibrating was 
 not found necessary oftener than once in one to two months. 
 
 PROCEDURE IN USING THE ELECTROSCOPE. 
 
 After the natural leak had been determined and also the pene- 
 trating ray discharge as control of the calibration, the electroscope was 
 evacuated to the desired degree, as determined by a mercury manome- 
 ter attached to one of the stopcocks. After such evacuation either 
 with an aspirator or a hand pump, the manometer was left connected 
 with the electroscope for a few minutes to make sure that the electro- 
 scope was air-tight. A microdrying tube was then connected to one 
 stopcock and the air containing emanation passed into the ionization 
 chamber from the gas burette, the ignition tube, or the ' ' emanating 
 tube," as the case might be. 
 
 After standing about three hours the instrument was charged for 
 about 10 to 15 minutes to the voltage used during measurement. 
 It appeared to make little difference, probably because of the sym- 
 metrical form of the ionization chambers, whether induced activity 
 was allowed to accumulate during the whole three hours in a chamber 
 with or without charge. Therefore, the authors employed the method 
 of charging for a short time immediately before measurement. Ten 
 duplicate measurements were then made over a range of 40 scale 
 divisions, from which the average rate of discharge was determined 
 before correcting for the natural leak. The corrected rate of discharge
 
 THE DETERMINATION OF URANIUM. 21 
 
 can be readily computed into terms of grams of radium by means of 
 a standardization with pitchblende carried out in exactly the same 
 manner as the measurement of the unknown sample of carnotite. 
 
 THE DETERMINATION OP URANIUM. 
 
 The method which proved most satisfactory for the determination 
 of uranium in carnotite is the gravimetric one of Ledoux & Co., 
 described by Moore and Kithil a and given below in full detail, includ- 
 ing the volumetric determination of vanadium. 
 
 GRAVIMETRIC METHOD FOR VANADIUM AND URANIUM IN CARNOTITE. 
 
 Treat from 2 to 5 grams of ore, according to the proportion of vanadium, iron, 
 and uranium present, in a covered beaker, with 10 c. c. of HC1 and let it stand 15 
 minutes, shaking it occasionally. Add 5 c. c. of HNO 3 and heat on a steam bath. 
 When quiet remove the cover and evaporate to dryness. Add 3 c. c. of HC1 and 5 
 c. c. of water to the residue and let it stand on the steam bath for a few minutes, stirring 
 occasionally. Dilute with 25 c. c. of hot water, filter into a small beaker, and wash the 
 residue with warm water. 
 
 Some ores do not yield all the vanadium to this treatment; a little of it may remain 
 with the insoluble residue. To make sure that all vanadium is in solution, ignite the 
 residue in a platinum dish, treat it with 5 c. c. of HF and evaporate to dryness on a 
 steam bath. Do not bake the residue. It is not necessary to expel all SiO 2 . Add 
 3 c. c. of HC1 to the residue from the HF treatment, and evaporate to dryness. Repeat 
 this treatment to insure expulsion of HF. Treat residue with 2 c. c. of HC1 and 2 
 c. c. of water and manipulate until any red crust is dissolved, then dilute the solution 
 with water and filter it into the main liquid. 
 
 Pass H 2 S into the liquid to separate copper, lead, and other metals of this group, 
 filter and boil the liquid to expel the H 2 S. Concentrate the liquid to 100 c. c., if nec- 
 essary, and oxidize it with an excess of H 2 2 and then neutralize with dry Na-jCC^, 
 adding 2 or 3 grams in excess. Boil the liquid for about 15 minutes until the yellowish 
 uranium precipitate dissolves, leaving a brown precipitate which is principally iron. 
 Filter and wash the iron precipitate with water, reserving the filtrate. Dissolve the 
 iron precipitate in the least possible amount of HN0 3 (1:1) and add 10 c. c. of H 2 a , 
 neutralize with Na^CC^, add an excess of 2 grams of Na^COj, and boil as before. Filter 
 into the beaker containing the first filtrate. The iron precipitate may contain a little 
 vanadium reserve it for further treatment. 
 
 Evaporate the united filtrates from the iron precipitation to a volume of about 200 
 c. c., add 10 c. c. of strong HNO 3 and boil until all C0 2 is expelled. Neutralize the 
 free acid with ammonia (until a slight permanent precipitate appears), then add 4 
 c. c. of HNO 3 for each 100 c. c. of liquid. Now add 10 c. c. of a 20 per cent lead acetate 
 solution, and [enough (about 20 c. c.) of a strong solution of ammonium acetate to 
 reduce the hydrogen ion concentration approximately to that of acetic acid.] The 
 object is to precipitate the vanadium as lead vanadate in an acetic acid solution. 
 The ammonium acetate solution may be made by mixing 80 c. c. of strong ammonia, 
 100 c. c. of water, and 70 c. c. of acetic acid 99 per cent pure. 
 
 Heat the liquid containing the lead-vanadate precipitate on the steam bath for one 
 hour or more, filter on a tight filter, and wash with warm water. Dissolve the pre- 
 cipitate in the least possible quantity of hot, dilute [not stronger than 1:5] nitric acid, 
 
 a Moore, R. B., and Kithil, K. L., A preliminary report on uranium, radium, and vanadium: BulL 70^ 
 Bureau of Mines, 1913, pp. 88-90.
 
 22 THE KADIUM-URANIUM EATIO IN CARNOTITES. 
 
 neutralize as before, add 3 c. c. of HNO 3 in excess, add 2 c. c. of lead acetate solution, 
 and repeat the precipitation of lead vanadate by adding ammonium acetate in excess, 
 filter and add the filtrate to the one from the first precipitation of lead vanadate. 
 Reserve the precipitate of lead vanadate for treatment as described below. Evaporate 
 the united filtrates from the lead vanadate to about 400 c. c., add 10 c. c. of strong 
 H 2 S0 4 to separate the bulk of the lead (derived from the excess of lead acetate) as 
 PbS0 4 , filter, and wash the precipitate with cold water. Neutralize the filtrate from 
 the PbSO 4 with ammonia and add freshly prepared (NH 4 )HS until the solution is 
 yellow and the uranium and what little lead is present are precipitated as sulphides. 
 Warm the mixture on a steam bath until the sulphides settle well. Filter and wash 
 slightly with warm water. 
 
 Dissolve the precipitate in a No. 2 beaker with hot dilute (1:2) HNO 3 , add 5 c. c. 
 of H 2 S0 4 and evaporate till fumes of H 2 SO 4 appear, cool and take up with water, boil, 
 and let the small precipitate of PbS0 4 settle until the solution is cold; filter, and wash 
 the precipitate with [a little very] dilute H 2 SO 4 . 
 
 SEPARATION OP ALUMINA. 
 
 Nearly neutralize the filtrate with ammonia; have the solutions cool (not warmer 
 than 30 C.), and add powdered carbonate of ammonia in about 2 grams excess to 
 precipitate the aluminum, let the precipitate settle, filter, and wash with warm water. 
 If the precipitate is bulky or is at all yellow, dissolve it in a little dilute H 2 SO 4 and 
 reprecipitate with ammonium carbonate as described above. Acidulate the filtrate 
 from the alumina with H 2 SO 4 and boil thoroughly to expel CO^ Make the liquid 
 slightly alkaline with NH 4 OH while it is hot, and heat on the water bath until the 
 ammonium uranate collects and settles. Filter and wash with very dilute (2 per 
 cent) solution of NH 4 NO 3 . Do not allow the precipitate to run dry on the filter after 
 the first washing. Dry the precipitate, ignite it in a porcelain crucible, and weigh 
 as U 3 O 8 . Dissolve the precipitate in HNO 3 and test it with H 2 O 2 for vanadium and 
 with (NH 4 ) 2 CO 3 for aluminum. 
 
 Dissolve the lead vanadate in dilute HNO 3 , add 10 c. c. of H 2 S0 4 , and evaporate the 
 mixture to fumes. Cool, take up with water [add fusion solution], add 10 c. c. of a 
 concentrated solution of S0 2 to the mixture, boil until the excess of S0 2 is expelled 
 and titrate the hot solution with a standard solution of potassium permanganate. 
 The S0 2 reduces the vanadium in solution from V 2 5 to V 2 4 . It is not necessary to 
 filter out the lead sulphate before boiling to expel S0 2 . The boiling is best done in a 
 large flask. In expelling the excess of SO 2 it is necessary to boil the liquid for at least 
 10 minutes after the smell of SO 2 can no longer be detected. 
 
 The iron precipitate that was produced by the addition of Na 2 C0 3 and H 2 2 to the 
 original acid solution may contain vanadium. Ignite the precipitate in a platinum 
 crucible and fuse the residue with Na 2 CO 3 , leach the fusion with water, filter, and 
 acidulate the filtrate with H 2 S0 4 . The filtrate may be addded to the main solution 
 before reducing with S0 2 , or reduced and titrated separately, as preferred. 
 
 For the details of other methods of control the reader is referred to 
 Bulletin 70 . 
 
 In general it may be stated that the most prevalent errors in the 
 determination of uranium result in the precipitation of some other 
 oxide, such as SiO 2 , A1 2 O 3 , or V 2 O 3 , along with uranium, which would 
 produce a low radium-uranium ratio. To guard against errors from 
 the presence of SiO 2 or A1 2 O 3 , the authors usually redissolved the U 3 O 8 
 
 a Moore, R. B., and Kithil, K. L., A preliminary report on uranium, radium, and vanadium: Bull. 70, 
 Bureau of Mines, 1914, pp. 82-91.
 
 RESULTS OF EXPERIMENTS. 23 
 
 precipitate, passed the solution through a Jones's reductor, and 
 determined the uranium volumetrically by titration with KMnO 4 
 solution. 
 
 RESULTS OF EXPERIMENTS. 
 
 The principal data in regard to the samples tested and the results 
 obtained are given below. For convenience of reference each ore is 
 designated by number, and the order of numbering is the same 
 throughout this paper. Radium values representing the sum of two 
 determinations were determined by the complementary method; 
 those determined by the ignition method are so designated; all others 
 were determined by the method of total emanation by solution hi a 
 single operation. 
 
 1. Sample of 65 pounds from Cripple Creek claim, Long Park, Paradox Valley, Colo. 
 U 3 O 8 content: 2.10; 2.08, and 2.12 per cent; average, 2.095 per cent; average U content, 
 1.78 per cent; average V 2 5 content, 2.53 per cent. Ra per gram X10 9 : 5.94, 6.11, 
 and 5.99 (ignition method); average, 6.02X10" 9 gram. Emanating power, 29.6 per 
 cent. Ra/U=3.38X10- 7 . 
 
 2. Small sample from the Rajah claim, Roc Creek, Paradox Valley, Colo. U 8 8 
 content: 33.19 and 33.24 per cent; average, 33.22 per cent. Average U content, 
 28.18 per cent; average V 2 5 content, 14.05 per cent. Ra per gram X10 8 : 1.50+ 
 8.71=10.21,1.67+8.34=10.01, 1.76+8.44=10.20; average, 10.14X10- 8 gram. Eman- 
 ating power, 16.2 per cent. Ra/U=3.59X10~ 7 . 
 
 3. Small sample from Black Fox claim, Bull Canon, south of Paradox Valley, Colo. 
 U 3 O 8 content: 1.63, 1.57, 1.60, and 1.58 per cent; average, 1.595 per cent. Average 
 U content, 1.35 per cent; average V 2 5 content, 5.22 per cent. Ra per gram X 10*: 
 2.15+2.06=4.21, 4.29, 4.30, 4.23 (ignition method); average, 4.26X10^ gram. 
 Emanating power, 50.5 per cent. Ra/U=3.16X10~ 7 . 
 
 4. Small sample from Florence claim, Long Park, Paradox Valley, Colo. U,0 8 
 content: 23.54 and 23.42 per cent; average, 23.48 per cent. Average U content, 
 19.92 per cent; average V 2 O 5 content, 10.63 per cent. Ra per gram X 10*: 
 1.404+5.861=7.27; 1.166+6.082=7.25; 7.33 (ignition method); average, 7.28X10"" 8 
 gram. Emanating power, 17.7 per cent. Ra/U=3.66X10~ 7 . 
 
 5. Small sample from a Curran claim, Long Park, Paradox Valley, Colo. U 3 O 8 
 content: 24.03, 23.43, 24.75, and 24.37 per cent; average, 24.25 per cent. Average 
 U content, 20.60 per cent; average V 2 O 5 content, 13.51 per cent. Ra per gramXIO 8 : 
 
 '2.18+2.77=4.95; 2.36+2.62=4.98; 4.95; 4.97 (ignition method); average, 4.96X10- 8 
 gram. Emanating power, 45. 8 per cent. Ra/U=2.4lXlO~ 7 . 
 
 6. Small sample of a concentrate prepared by a method which may possibly have 
 affected the Ra/U ratio. Hence the data for this sample are not included in Table I. 
 U 3 O 8 content: 9.20 and 9.05 per cent; average, 9.125 per cent. Average U content, 
 7.74 per cent; average V 2 5 content, 10.08 per cent. Ra per gramXIO 8 : 2.166; 
 2.167; 2.184 (ignition method); average, 2.17X10" 8 gram. Emanating power, 30.4 per 
 cent. Ra/U=2.80XlO- 7 . 
 
 7. Small sample from Florence claim, Long Park, Paradox Valley, Colo. U 3 O 8 con- 
 tent: 3.16, 3.17, 3.23, and 3.19 per cent; average, 3.185 per cent. Average U content, 
 2.70 per cent; average V 2 O 5 content, 4.82 per cent. Ra per gramXIO 9 : 4.26+6.35= 
 10.61; 10.86; 10.58; 10.60; 10.94 (ignition method); average, 10.72X10~ 9 gram. 
 Emanating power, 39.7 percent. Ra/U=3.97X10- ? . 
 
 8. Sample of 3,016 pounds from a Cummings claim, Bull Canyon, south of Paradox 
 Valley, Colo. U 3 8 content: 4.78, 4.72, 4.62, and 4.61 per cent; average, 4.68 per cent.
 
 24 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 Average U content, 3.97 per cent; average V 2 O 5 content, 4.10 per cent. Ra per gram 
 X10 9 : 4.38+8.93=13.31; 4.45+8.50=12.95; 12.42; 12.90 (ignition method); 13.67; 
 average 13.05 XlO" 9 gram. Emanating power, 33.9 per cent. Ra/U=3.29XlO~ 7 . 
 
 9. Sample of 29,118 pounds from same locality as No. 8. U 3 O 8 content: 1.52, 1.57, 
 and 1.48 per cent; average, 1.523 per cent. Average U content, 1.29 per cent; 
 average V 2 S content, 4.00 per cent. Ra per gramXlO 9 : 1.052+3.294=4.35; 0.719+ 
 3.500=4.22; 4.43; 4.41 (ignition method); average, 4.35X10" 9 gram. Emanating 
 power, 20.4 per cent. Ra/U=3.42XlO~ 7 . 
 
 10. Sample of about 4,000 pounds from same place as No. 5. U 3 O 8 content: 2.31, 
 2.45, 2.35, and 2.48 per cent; average, 2.40 per cent. Average U content, 2.04 per 
 cent; average V 2 O 5 content, 5.27 per cent. Ra per gramXlO 9 : 7.23; 7.40; 7.30 
 (ignition method); average, 7.31X10"* gram. Emanating power, 29.0 per cent. 
 Ra/U=3.58X10- 7 . 
 
 ' 11. Small sample from Melrose claim, Green River district, Utah. U 3 8 content: 
 4.14, 4.11, 4.12, and 4.16 per cent; average, 4.13 per cent. Average U content, 3.50 
 per cent; average V 2 O 5 content, 5.07 per cent. Ra per gramXlO 9 : 4.83+5.74=10.57; 
 5.05+5.73=10.78; 11.12; 10.87; 11.41 (ignition method); average* 10.95 X10" 9 gram. 
 Emanating power, 45.1 per cent. Ra/U=3.13X10~ 7 . 
 
 [12. (Standard) pitchblende from Kirk mine, Gilpin County, Colo. U 3 8 content: 
 76.40 and 76.58 per cent; average, 76.50 per cent. Average U content, 64.9 per cent. 
 Ra per gram: 2.16X10" 7 (calculated from Heimann and Marckwald'so Ra/U ratio of 
 3.328X10" 7 ). Emanating power 2.7 per cent, by two determinations of 5.98X10" 9 
 and 5.73X10" 9 curies, respectively.] 
 
 13. Sample of a carload lot (about 30 tons) from the claims of the Crucible Steel 
 Co., Paradox Valley, Colo. U 3 8 content: 2.74 and 2.82 per cent; average, 2.78 per 
 cent. Average U content, 2.36 per cent; average V 2 6 content, 4.67 per cent. Ra per 
 gramXlO 9 : 3.51+4.32=7.83; 7.89 (ignition method); average, 7.86X10"-* gram. 
 Emanating power, 44.7 per cent. Ra/U=3.34XlO~ 7 . 
 
 14. Sample of a carload lot (about 25 tons) from the same locality as No. 13. 
 U 3 O 8 content: 3.91 and 3.95 per cent; average, 3.93 per cent. Average U content, 
 3.33 per cent; average V 2 5 content, 5.12 per cent. Ra per gramXlO 9 : 3.90+7.19= 
 11.09; 11.09; average, 11.09X10" 9 gram. Emanating power, 35.2 per cent. Ra/U= 
 3.33X10~ 7 . 
 
 15. Sample of a carload lot (about 20 tons) from same locality as No. 13. U 3 O 8 
 content: 2.85 and 2.82 per cent; average, 2.835 per cent. Average U content, 2.41 per 
 cent; average V 2 5 content, 4.72 per cent. Ra per gramXlO 9 : 3.488+4.467= 
 7.955; 8.076; average, 8.02X10" 9 gram. Emanating power, 43.4 per cent. Ra/U= 
 3.33 X10~ 7 . 
 
 16. Sample of a carload lot (about 22 tons) from same locality as No. 13. U 3 8 
 content: 2.52 and 2.54 per cent; average, 2.53 per cent. Average U content, 2.16 per 
 cent; average V 2 O 5 content, 3.75 per cent. Ra per gramXlO 9 : 3.191+3.916=7.107; 
 7.077; 7.219 (ignition method); 7.174; average, 7.14X10~ 9 gram. Emanating power, 
 44.9 per cent. Ra/U=3.32x'lO~ 7 . 
 
 17. Sample of a carload lot (about 19 tons) from same locality as No. 13. U 3 0s 
 content: 3.05, 3.03, and 3.06 per cent; average, 3.05 per cent. Average U content, 
 2.59 per cent; average V 2 5 content, 4.66 per cent. Ra per gramXlO 9 : 8.66; 8.65 
 (ignition method); average, 8.66X10" 9 gram. Emanating power, 47.7 per cent. 
 Ra/U=3.34X10~ 7 . 
 
 18. Small sample from Kelly No. 3 lode, west of Mclntyre district, Colorado, near 
 Utah-Colorado boundary. U 3 8 content: 25.63 and 25.71 per cent; average, 25.67 per 
 cent. Average U content, 21.77 per cent; average V 2 O 5 content, 22.3 per cent. Ra 
 
 a Heimann, Berta, and Marckwald, W., tiber den Radiumgehalt von Pechblenden: Jahrb. Radioakt. 
 Elektronik, Bd. 10, 1913, p. 299; Physik. Ztschr., Bd. 14, 1913, p. 303.
 
 BESULTS OF EXPERIMENTS. 25 
 
 per gramXIO 8 : 1.224+6.156=7.38; 7.34; 7.37 (ignition method); average, 7.36X10-* 
 gram. Emanating power, 16.6 per cent. Ra/U=3.38X10~ 7 . 
 
 19. About 60 pounds of a composite sample of several ores. U 3 8 content: 3.18, 
 3.26, 3.17, and 3.10 per cent; average, 3.18 per cent. Average U content, 2.70 per cent- 
 average V 2 5 content, 4.03 per cent. Ra per gramXIO 9 : 8.902 (ignition method); 
 8.935; average, 8.92X10" 9 gram. Emanating power, 33.5 per cent. Ra/U= 
 3.30X10" 7 . 
 
 20. Small sample from Horse Mountain, Eagle County, Colo. U 3 8 content: 7.81 
 and 7.75 per cent; average, 7.78 per cent.' Average U content, 6.60 per cent; average 
 V 2 5 content, 8.80 per cent. Ra per gramXIO 9 : 9.85+19.77=29.62; 29.91; 30.62; 
 30.98 (ignition method); average, 30.3 X10" 9 gram. Emanating power, 29.6 per cent 
 Ra/U=4.59X10- 7 . 
 
 21. Small sample from a Meyer claim, South Park, Colo. U 3 8 content: 9.52 and 
 9.20 per cent; average, 9.36 per cent. Average U content, 7.94 per cent; average 
 V 2 O 5 content, 3.85 per cent. Ra pergramXIO 8 : 1.07+1.31=2.38; 2.36; 2.37 (ignition 
 method); average, 2.37X10" 8 gram. Emanating power, 45.2 per cent. Ra/U= 
 2.99X10" 7 . 
 
 22. A lot of several hundred pounds from the Wade and Taylor claims, Pac Creek, 
 near Moab, Utah. U 3 O 8 content, 7.52 per cent; U content, 6.38 per cent; average 
 V 2 O 5 content, 11.23 per cent. Ra per gramXIO 8 : 0.344+1.764=2.11; 2.12; 2.15 
 (ignition method); average, 2.13X10" 8 . Emanating power, 16.2 per cent. Ra/U= 
 3.34X10- 7 . 
 
 23. Sample of 1,120 pounds from the same locality as No. 22. U 3 O 8 content, 11.62 
 per cent; U content, 9.86 per cent. Ra per gramXIO 8 : 3.29; 3.26 (ignition method); 
 average, 3.28X10" 8 gram. Emanating power, 25.1 per cent. Ra/U=3.33X10~ 7 . 
 
 24. Sample of about 1 ton of ore of unknown origin, very finely ground, possibly a 
 mill product that had been mixed with a low-grade carnotite after the radium had 
 been largely removed. U 3 8 content: 8.83 and 8.85 per cent; average, 8.84 per cent. 
 Average U content, 7 .50 per cent; average V 2 5 content, 6.87 per cent. Ra per gramX 
 10 9 : 3.99; 3.88; 4.24 (ignition method); average, 4.04X10^ gram. Ra/U=0.54X10- 7 . 
 
 The reasons for doubting this sample to be a natural carnotite ore are rather numer- 
 ous. Its Ra/TJ ratio is abnormally low, and its origin could not be ascertained. 
 Under the microscope it shows a network of crystalline needles partly soluble in 
 water (apparently CaS0 4 ), such as could not have existed in the original ore, but must 
 have formed after the ore was ground, because their length is several times the average 
 diameter of other particles. On ignition considerable sulphur is distilled off, probably 
 owing to reduction of sulphates by organic matter. For these reasons the authors do 
 not believe it to be a natural carnotite, and have presented the data for whatever 
 general interest they may have, without including them in Table 1.
 
 THE RADIUM-URANIUM RATIO IN CARNOTITES. 
 
 A summary of the results obtained in the experiments with car- 
 no tite ores is presented in Table 1 following: 
 
 TABLE I. Results of experiments with carnotites. 
 
 
 
 
 
 
 
 
 Percent- 
 
 
 
 
 
 Grams of 
 
 
 Radium- 
 
 age of 
 normal 
 
 No. of 
 
 Locality. 
 
 U,0 8 . 
 
 U. 
 
 radium 
 X10 9 per 
 
 Emanat- 
 ing 
 
 uranium 
 ratio. 
 
 ratio 
 (pitch- 
 
 ore. 
 
 
 
 
 gram of 
 
 power. 
 
 Ra 
 
 blende 
 
 
 
 
 
 ore. 
 
 
 TJ X10 . 
 
 ratio= 
 
 
 
 
 
 
 
 
 100 per 
 cent).o 
 
 
 
 Perct. 
 
 Perct. 
 
 
 Per cent. 
 
 
 
 5 
 
 Long Park, Colo 
 
 24.25 
 
 20.6 
 
 49.6 
 
 45.8 
 
 2.41 
 
 72.4 
 
 21 
 
 South Park, Colo 
 
 9.36 
 
 7.94 
 
 23.7 
 
 45.2 
 
 2.99 
 
 89.8 
 
 11 
 
 Green River, Utah 
 
 4.13 
 
 3.50 
 
 10.95 
 
 45.1 
 
 3.13 
 
 94.0 
 
 3 
 
 8 
 
 Bull Canyon, Colo 
 Do 
 
 1.60 
 4 68 
 
 1.35 
 3 97 
 
 4.26 
 13 05 
 
 50.5 
 33 9 
 
 3.16 
 3.29 
 
 94.9 
 
 *98 8 
 
 19 
 
 
 3.18 
 
 2.70 
 
 8.92 
 
 33.5 
 
 3.30 
 
 99.1 
 
 16 
 
 Long Park, Colo 
 
 2.53 
 
 2.16 
 
 7.14 
 
 44.9 
 
 3.32 
 
 *99.7 
 
 14 
 
 
 3.93 
 
 3.33 
 
 11.09 
 
 35.2 
 
 3.33 
 
 *100.0 
 
 15 
 
 Do 
 
 2.84 
 
 2.41 
 
 8.02 
 
 43.4 
 
 3.33 
 
 *100 
 
 23 
 
 Moab Utah 
 
 11 62 
 
 9 86 
 
 32 8 
 
 25 1 
 
 3 33 
 
 *100 
 
 13 
 
 Long Park, Colo 
 
 2.78 
 
 2.36 
 
 7.86 
 
 44.7 
 
 3.34 
 
 *100.3 
 
 17 
 
 Do 
 
 3.05 
 
 2.59 
 
 8.66 
 
 47.7 
 
 3.34 
 
 *100.3 
 
 22 
 
 Moab Utah 
 
 7 52 
 
 6 38 
 
 21 3 
 
 16 2 
 
 3 34 
 
 *100 3 
 
 18 
 1 
 
 Mclntyre district, Colo 
 Long Park Colo 
 
 25.67 
 2 10 
 
 21.77 
 1 78 
 
 73.6 
 6 02 
 
 16.6 
 29 6 
 
 3.38 
 3 38 
 
 101.5 
 101 5 
 
 9 
 
 Bull Canyon, Colo 
 
 1.52 
 
 1.29 
 
 4.35 
 
 20.4 
 
 3.42 
 
 *102. 7 
 
 10 
 
 Long Park, Colo 
 
 2.40 
 
 2.04 
 
 7.31 
 
 29.0 
 
 3.58 
 
 *107. 5 
 
 2 
 
 Paradox Valley Colo 
 
 33 22 
 
 28 18 
 
 101 4 
 
 16 2 
 
 3 59 
 
 107 8 
 
 4 
 
 Long Park, Colo 
 
 23.48 
 
 19.92 
 
 72.8 
 
 17.7 
 
 3.66 
 
 109.9 
 
 7 
 
 Do.... 
 
 3.19 
 
 2.70 
 
 10.72 
 
 39.7 
 
 3.97 
 
 119.2 
 
 20 
 
 Eagle County, Colo 
 
 7.78 
 
 6.60 
 
 30.3 
 
 29.6 
 
 4.59 
 
 137.8 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 101 8 
 
 
 
 
 
 
 
 
 
 a In results preceded by an asterisk the sample represents a large quantity of ore (from several hundred 
 pounds to 25 tons). 
 6 Composite of several ores. 
 
 DISCUSSION OF RESULTS. 
 
 On inspecting the last two columns of Table I there appears to be 
 only one possible conclusion as to the radium-uranium ratio of car- 
 notite; namely, that it is identical with that of pitchblende in all 
 large quantities of well-sampled ore. This appears to be true regard- 
 less of the locality of the deposit or the composition of the ore. The 
 low and high ratios are found only in samples representing small 
 quantities of ore, and the variations are apparently due to local 
 transposition of radium within the ore bed; they are completely 
 equalized on sampling sufficient quantities of ore. The authors are 
 not prepared to go further into the nature of this transposition at the 
 present time, because, as already stated, the samples were not col- 
 lected with this object in view. 
 
 Of course, the fact that the average of all ratios in Table I should be 
 within 2 per cent of the normal ratio is somewhat accidental; but 
 that the average for all the large samples is within 1 per cent of the 
 normal ratio appears by no means accidental, and seems to represent 
 about the average of the limits of experimental error.
 
 RESULTS OF EXPERIMENTS. 27 
 
 The question naturally presents itself as to whether high and low 
 ratios for other minerals can be explained in the same way as for car- 
 notite. As far as we are aware it is true that determinations of the 
 radium-uranium ratio have been made, in all the minerals examined, 
 on small samples only. On the other hand, it is to be recalled that 
 high ratios had not been hitherto reported except for primary min- 
 erals, which are not affected as much by the action of water as sec- 
 ondary minerals are. 
 
 Furthermore, in the case of autunite, in which leaching certainly 
 does produce very low ratios, no high ratios have ever been found to 
 support the transposition theory as put forward for carnotite. In 
 such instances it has been found that the leaching process removes the 
 radium completely from association with the original uranium parent, 
 disseminating it widely or, in exceptional cases, forming deposits con- 
 taming considerable radium with no uranium, as found by Danne hi 
 a specimen of pyromorphite from Issy L'Eveque. 
 
 The difference in the completeness of the removal of radium by 
 leaching exhibited by autunite and carnotite may be due to the fact 
 that the latter occurs hi a region of very low rainfall; in fact, aridity 
 seems to be a necessary condition for the existence of carnotite. 
 Under such conditions and in view of the fact that the extent of 
 many carnotite deposits is large, a transposition of radium might be 
 expected rather than a complete removal. 
 
 The high degree to which carnotite gives up its emanation by 
 diffusion as shown in Table 1 and discussed on pages 10 to 12, appears 
 rather remarkable. The property does not seem to be connected 
 with any other known properties of the ores and the authors are not 
 able at present to do more than call attention to the fact, and also 
 to note that carnotite appears to furnish in the solid state a more 
 abundant source of radium emanation than any other mineral with 
 the same radium content. 
 
 In conclusion it may be stated that from this investigation there 
 seems to be no justification for regarding the radium-uranium ratio 
 in commercial quantities of carnotite as being low or in any way ab- 
 normal. The practice of evaluating the ore from its uranium content 
 appears to be correct within the limits of reliability of uranium de- 
 terminations. In a later paper the authors expect to show that it 
 will be more convenient as well as accurate to determine radium 
 directly than to use the indirect method of a uranium analysis. It 
 is, of course, needless to say that the latter procedure must always be 
 the recourse when the genuineness of the product is uncertain or any 
 other abnormality is suspected. However, in the case of a com- 
 mercial quantity of correctly sampled carnotite, the uranium content 
 
 o Danne, Jacques, Sur un nouveau mineral radifere: Compt. rend., t. 140, 1905, p. 241.
 
 28 THE RADIUM-UEANIUM BATIO IN CAENOTITES. 
 
 of which is accurately known, there remain no grounds whatsoever 
 to suspect the radium content as being any less than in the proportion 
 of 1 part of radium to 3,000,000 parts of metallic uranium. 
 
 SUMMARY. 
 
 1. Samples of carnotite representing large quantities of ore (a 
 few hundred pounds to several tons) show a radium-uranium ratio 
 identical with that of pitchblende (3.33X10" 7 ); this ratio is also in 
 accord with the value calculated from radiation data. 
 
 2. Samples from small quantities of ore (hand specimens up -to a 
 few pounds) tend to exhibit abnormal ratios. In one instance the 
 ratio was as low as 2.48X1 0~ 7 , and in another as high as4.6xlO~ 7 . 
 
 3. The most plausible explanation for these abnormal ratios seems 
 to be that of transposition of radium within the ore bed, producing 
 local differences which are equalized in large samples. 
 
 4. The "emanating power" of carnotite is high, and varies from 16 
 to 50 per cent. 
 
 5. In order to obtain concordant results by the Boltwood emana- 
 tion method it was found desirable to determine the emanation 
 liberated by solution in the same sample from which the emanating 
 power had just been determined, thus making the two determina- 
 tions strictly "complementary." 
 
 6. Radium may be easily determined in one operation by the ema- 
 nation method, either by solution or by ignition from tubes in which 
 it has been sealed for one month to reach equilibrium. 
 
 7. In contrast with the success of the solution and the ignition 
 methods for de-emanating carnotite, the method of fusion with 
 sodium and potassium carbonates and the fusion-and-solution 
 method both gave low results and were abandoned. 
 
 ACKNOWLEDGMENT. 
 
 The authors take pleasure in acknowledging their indebtedness to 
 Prof. R. B. Moore, physical chemist of the Bureau of Mines, for his 
 helpful advice during this investigation.
 
 PUBLICATIONS ON MINERAL TECHNOLOGY. 
 
 A limited supply of the following publications of the Bureau of 
 Mines is temporarily available for free distribution. Requests for all 
 publications can not be granted, and to insure equitable distribution 
 applicants are requested to limit their selection to publications that 
 may be of especial interest to them. Requests for publications should 
 be addressed to the Director, Bureau of Mines. 
 
 BULLETIN 3. The coke industry of the United States as related to the foundry, by 
 Richard Moldenke. 1910. 32 pp. 
 
 BULLETIN 12. Apparatus and methods for the sampling and analysis of furnace 
 gases, by J. C. W. Frazer and E. J. Hoffman. 1911. 22 pp., 6 figs. 
 
 BULLETIN 47. Notes on mineral wastes, by C. L. Parsons. 1912. 44 pp. 
 
 BULLETIN 53. Mining and treatment of feldspar and kaolin in the southern Appa- 
 lachian region, by A. S. Watts. 1913. 170 pp., 16 pis., 12 figs. 
 
 BULLETIN 64. The titaniferous iron ores in the United States, their composition 
 and economic value, by J. T. Singewald, jr. 1913. 145 pp., 16 pis., 3 figs. 
 
 BULLETIN 67. Electric furnaces for making iron and steel, by D. A. Lyon and R. 
 M. Keeney. 1913. 142 pp., 36 figs. 
 
 BULLETIN 70. A preliminary report on uranium, radium, and vanadium, by R. B. 
 Moore and K. L. Kithil. 1913. 100 pp., 2 pis., 2 figs. 
 
 BULLETIN 71. Fuller's earth, by C. L. Parsons. 1913. 38 pp. 
 
 BULLETIN 77. The electric furnace in metallurgical work, by D, A. Lyon, R. M. 
 Keeney, and J. F. Cullen. 1914. 216 pp., 56 figs. 
 
 BULLETIN 81. The smelting of copper ores in the electric furnace, by D. A. Lyon 
 and R. M. Keeney. 1914. 
 
 BULLETIN 84. Metallurgical smoke, by C. H. Fulton. 1914. 90 pp., 5 pis., 15 figs. 
 
 TECHNICAL PAPER 15. An electrolytic method of preventing corrosion of iron or 
 steel, by J. K. Clement and L. V. Walker. 1913. 19 pp., 10 figs. 
 
 TECHNICAL PAPER 31. Apparatus for thexact analysis of flue gas, by G. A. Burrell 
 and F. M. Seibert. 1913. 12 pp., 1 fig. 
 
 TECHNICAL PAPER 36. The preparation of specifications for petroleum products, 
 by I. C. Allen. 1913. 12 pp. 
 
 TECHNICAL PAPER 41. The mining and treatment of lead and zinc ores in the 
 Joplin district, Missouri; a preliminary report, by C. A. Wright. 1913. 43 pp., 5 figs. 
 
 TECHNICAL PAPER 50. Metallurgical coke, by A. W. Belden. 1913. 48 pp., 
 Ipl., 23 figs. 
 
 TECHNICAL PAPER 60. The approximate melting points of some commercial cop- 
 per alloys, by H. W. Gillete and A. B. Norton. 1913. 10 pp., 1 fig. 
 
 TECHNICAL PAPER 81. The vapor pressure of arsenic trioxide, by H. V. Welch and 
 L. H. Duchak. 1915. 22 pp., 2 figs.
 
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