EXCHANGE TELLURIUM Jl Spectrographic Study Ernest Victor Jones, M.A. PRESENTED TO THE FACULTY OF VANDERBILT UNIVERSITY AS A THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY TELLURIUM JI Spectrographic Study Ernest Victor Jones, M.A. PRESENTED TO THE FACULTY OF VANDERBILT UNIVERSITY AS A THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY A: :>':"'::' : -V- . / ACKNOWLEDGMENT. I WISH to express my sincere gratitude and thanks to Dr. William L. Dudley, of this University, and his able corps of assistants for their cooperation and support in this work. I am especially indebted to Dr. Dudley for his enthusiastic interest in and careful direction of my work, and to Mr. Paul C. Bowers for his valuable aid in manipulating apparatus and in other ways. 4693 VI MY BELOVED WIFE EUNICE BETH VAUGHAN WHOSE ENTHUSIASTIC CO-OPERATION AND SYMPATHETIC HELPFULNESS HAVE BEEN MY CHIEF IN- SPIRATION TO GRADUATE STUDIES CONTENTS. PAGH. Introduction 9 The Object of This Study 13 Materials Used 13 The Apparatus 14 The Comparator 15 The Electrodes 15 Plan of Investigation 17 The Comparator Method 17 Methods of Procedure 18 Results and Conclusions 24 The Spark Spectrum of Tellurium 27 Summary 32 INTRODUCTION. IN 1869 Mendeleeff, 1 in announcing the periodic law, pointed out that the atomic weight of an element can sometimes be cor- rected as soon as its properties' are known, and he said that the atomic weight of tellurium must be not 128, as it was then given, but 123 to 126. This statement at once suggested a problem which challenged the attention of a number of chemists, and has since been the subject of many researches. Various theories have been advanced to explain the anomalous position of tellurium in the periodic system. Tellurium, from a consideration of its general properties, falls into Group VI., Series VII.', of the periodic table. Its atomic weight, however, now given as 127.5, * s higher than that of iodine, which is found in Group VII. , Series VII., with an atomic weight of 126.92, which fact is out of harmony with the principles upon which the periodic table was constructed. With few exceptions, 2 the solution of this problem has been sought in the direction indicated by Mendeleeff namely, the lowering of the atomic weight of tellurium. After an investigation extending over a period of six years, Brauner 3 first reported his conclusions in 1889. He held that tel- lurium is undoubtedly a complex substance, probably a mixture of three elements, as is the case with gadolinium. The same year that Brauner's report appeared, a theory was advanced by Griinwald, 4 who argued that the coincidence in certain lines in the ultra-violet spectra of tellurium, copper, and antimony pointed to a common impurity in these three elements. This impurity he thought to be an unknown element of the tellurium group, with an atomic weight of about 212. This view was strengthened by Mendeleeff, 5 who in 1889, in illustrating the prediction of new elements through the periodic law, outlined briefly the properties of an unknown element which he called dvitellurium. He as- signed to it an atomic weight of 212 and placed it in the tellurium 'Ber, 13, 1799- 2 Zeit. Anorg. Chem. 12, 98. 3 Jour. Chem. Soc. 55, 382. 4 Monatsh. 10, 829; Abs. Jour. Chem. Soc. 58, 434. 6 Jour. Chem. Soc. 55, 649. [10] group. In 1895 Brauner, 1 who had continued the work previously cited, using larger amounts of tellurium and better methods of purification, said : "I conclude that it is very improbable that the abnormally high atomic weight of tellurium is due to an admix- ture of a higher homologue of tellurium having the atomic weight of 214." He suggested as a more probable theory that the ordi- nary tellurium (like didymium) consisted of "equal parts (atoms) of true telkirium and tetrargon, for ^=127.7." He pointed out as a significant fact that a contemporary 2 had arrived at identically the same conclusion from an entirely different view- point by a process of reasoning based on certain laws of harmony of spectral lines. Standenmeyer 8 reported during the same year (1895) that fractional crystallization of telluric acid gave no evi- dence of breaking down the tellurium. A similar conclusion was reached by Norris, Fay, and Edgerly 4 in 1899 through fractional crystallization of potassium brom-tellurate. Later and more ex- tensive work by Norris 5 confirmed this conclusion. Koethner 6 in 1901 departed somewhat from the ordinary methods of procedure in applying the spectrograph as a test of the purity of the tellurium compounds prepared by the methods previously used, and declared that probably no investigator had yet succeeded in getting absolutely pure tellurium. He found characteristic lines in the spectra of the preparations by BraunerV and Staudenmeyer's 7 methods, indicating traces of copper, anti- mony, silver, arsenic, and gold. In a like manner the prepara- tions by Norris, Fay, and Edgerly's 7 method showed traces of sil- ver and copper even after numerous recrystallizations. Koeth- ner succeeded in separating all traces of known elements from tellurium and recommended as a very satisfactory process the redistillation under 9-12""" pressure of the product obtained by reducing with sulphur dioxide the recrystallized basic nitrate of tellurium. This tellurium, however, which was probably of the highest degree of purity yet attained, he found to exhibit in its ultra-violet spectrum a number of lines coincident with lines in the spectra of copper, antimony, thallium, and indium. These 1 Jour. Chem. Soc. 67, 549. 5 Jour. Amer. Chem. Soc. 28, 1675. 2 Compt. rend. 120, 361. "Ann. 319, I, 3 Zeit. Anorg. Chem. 10, 189. 7 Loc. cit. *Amer. Chem. Jour. 23, 105. [11] coincident lines were shown also by tellurium obtained from SteinerV diphenyl telluride of constant boiling point, which was free from all known impurities, as shown by the spectrograph. These were not characteristic lines, but they did not change in appearance in the least throughout the various processes of puri- fication. No record is given of their wave length determinations. Koethner did not agree with Griinwald 2 in attributing these co- incident lines to a common impurity in these elements. His con- clusions were that these elements must be regarded as having certain properties in common, and that he had obtained tellurium free from all impurity. Gutbier 3 in 1905 tried a new method similar to Koethner's, but concluded that no change ffad been produced in the atomic weight of tellurium. Two years later Baker and Bennett, 4 after extensive investigations of tellurium covering thirteen years, declared in favor of elementary tellurium with an atomic weight of 127.6. In the same year (1907) Marck- wald, 5 by several hundred recrystallizations of telluric acid, ob- tained 20 fractions which agreed perfectly in properties, thus in- dicating uniform composition for tellurium. However, his value for atomic weight 126.85 was lower than that usually given. He repeated his atomic weight determinations by a volumetric method, 6 which he considered more accurate, and got a mean value 'of 127.61. Browning and Flint 7 in 1909, using hydrolysis of a hydrochloric acid solution of tellurium tetrachloride, got some very interesting results. Two fractions were obtained which were designated as alpha (the more easily hydrolyzed part) and beta (the part remaining in the solution). The alpha fraction gave an atomic weight of 126.53, an d the beta fraction an atomic weight of 128.97. These results were confirmed by three methods of atomic weight determinations. Viewed in the light of Brauner's conclusions and Mendeleefs predictions, these results are exceedingly interesting. Flint 8 continued this work, making ten fractionations by hydrolysis of the tetrachloride solu- tion, and got fractions of the more easily hydrolyzed tellurium, which exhibited a progressive diminution of the atomic weight. The last fraction, of more than 20 grams, gave by the basic ni- a Ber. 34, 570. 5 Ber. 40, 4730. 2 Loc. cit. 6 Ber. 43, 1710. 3 Ann. 342, 266. 7 Amer. Jour. Sci. 28, 347. *Jour. Chem. Soc. 91, 1849. 8 Amer. Jour. Sci. 30, 209. [12] trate method, as a mean of seven determinations, an atomic weight of 124.3. The final residue from the less easily hydrolyzed portions was reported as containing a small amount of an un- identified substance very similar to tellurium, though not identical with it in its properties. The preceding pages give a brief survey of the more important investigations of the abnormalities of tellurium that had been made up to the time of beginning the investigation herein described. 1 The general consensus of opinion favored the elementary state of tellurium with 127.5 as the accepted figure for its atomic weight. However, the work of Marckwald 2 in 1907, of Browning and Flint 2 in 1909, and especially of Flint 8 in 1910, indicated that the question of the homogeneity of tellurium was not as yet finally settled. The success of Koethner 2 with the spectrograph made it seem worth while to again, in the light of recent developments, make use of the spectrograph in an investigation of the complexity of tellurium. 1 While this work was in progress Harcourt and Baker (Chem. News, 104, 260) reported some recent work on tellurium. They repeated Flint's method of fractionation by hydrolysis, which gave him tellurium with a low atomic weight, 124.32, as determined by the basic nitrate method. They, however, used the tetra-bromide method for determining the atomic weight, and got the usual value, 127.54. They discussed Flint's work and attributed his low atomic weight to the presence of tellurium trioxide in his tellurium dioxide, the weight of which was used in calculating the atomic weight. 2 Loc. cit. - THE OBJECT OF THIS STUDY. 1. To test some tellurium purified in this laboratory. 2. To make a comparative study of the products of fractional precipitation of tellurium from a hydrochloric acid solution of tellurium tetrachloride by hydrazine hydrochloride. 3. To investigate very carefully the final residues. 4. To study minutely the ultra-violet spectrum of tellurium. MATERIALS USED. The tellurium which formed the basis of this investigation was obtained as crude tellurium dioxide from the Baltimore Copper Smelting and Refining Company and purified in this laboratory by Dr. Dudley and Mr. Bowers in the following manner : The silica present was dehydrated and removed by repeated evaporation to dryness of a hydrochloric acid solution of the crude material and the tellurium dioxide finally dissolved in hydro- chloric acid. The selenium was removed by fractional precipita- tion with sodium sulphite in a cold acid solution. The selenium came down first and was filtered off. The tellurium was thrown out of a hot acid solution by adding sodium sulphite until most of the acid had been neutralized and passing sulphur dioxide into the hot solution. The precipitated tellurium was oxidized with nitric acid and evaporated to dryness twice with hydrochloric acid and taken up in the least possible excess of hydrochloric acid and filtered. Any silver present was left on the filter as the chlo- ride. The tellurium was precipitated again, as above, with sodium sulphite and sulphur dioxide, filtered by inverse filtration, digested with hydrochloric acid (i to i), and washed by inverse filtra- tion with ammonia-free water until all the acid was removed. It was then converted into basic nitrate by treating it with nitric acid (sp. gr. 1.25) and crystallized out by evaporation at 70 degrees centigrade. Part of the nitrate was recrystallized from nitric acid ; but owing to great difficulty in getting it all to dissolve in nitric acid this process was abandoned and the nitrate was heat- ed carefully in a porcelain crucible to convert it into the dioxide. . The dioxide was reduced and the tellurium distilled and redistilled by heating to dull redness in a porcelain boat within a silica tube while a current of dry hydrogen gas was passing through the tube. [14] The hydrazine hydrochloride was prepared from hydrazine sul- phate by adding a very slight excess of barium chloride and pre- cipitating the excess of barium by carefully adding dilute sulphuric acid. Only Kahlbaum chemicals and ammonia-free water were used. THE APPARATUS. The spectrograph used in this study is an excellent Style C quartz spectrograph, made by the A. Hilgar (Limited) Optical Works at London. It consists of two quartz, lenses of 24-inch focus and a dispersion system of one Cornu quartz prism. This gives a spectrum of wave lengths from 8,000 to 1,900 tenth- meters, which is recorded on a photographic plate 4x10 inches in size, carried in a plate holder which can be shifted by means of a thumbscrew so that one plate may be exposed in a dozen different positions. A section of a quartz cylinder is used to focus the light in a sharp line on a vertical slit regulated by a microm- eter screw. By modifying the slide for the slit, as indicated in A r % Figures I and 2, it was made possible to photograph seven spectra in each position so that as many as 84 spectra may be photo- graphed on a single plate. By shifting the old form of slide from position A to position B the slit at ^ would be shortened from a a to b b'. By shifting the new form of slide we expose different parts of the slit at openings a, b, c, d, e, f, and g, and thus make seven exposures, one above the other, without moving the plate. This proved very useful in comparing the spectra of [15] the different elements and of the different fractions of tellurium, since it made the spectra so narrow that four could be brought at the same time into the field of the comparator microscope. The photographic plates used were Cramer's Special Spectrum Plates, sensitive throughout the entire spectrum, and Cramer's Crown Plates, specially sensitive in the ultra-violet region. About seven hundred photographs of spectra were examined in this in- vestigation. THE COMPARATOR. The instrument used is of the usual type. It consists of two low-power microscopes firmly mounted six inches apart. Be- neath these is a movable stage which carries under the right-hand miscroscope a scale graduated in tenths of a millimeter, and under the microscope on the left a table for holding the plates. The plates were cut in four parts and the pieces placed, one at a time, on the table under the left-hand microscope, and the relative positions of the spectral lines read off on the scale under the right-hand microscope as the stage was moved along. These scale readings were used in determining the wave lengths, as ex- plained later in this paper. THE ELECTRODES. Since tellurium, especially in a finely divided state, is very easily oxidized, the making of the electrodes becomes somewhat difficult. The following method, suggested by Dr. Dudley, works very successfully : A piece of glass tubing (a, Fig. 3) about 35 centimeters long and of ynm bore was plugged with loosely packed asbestos (b) about 5 centimeters from one end. The precipitated or powdered tellurium (c) was placed in this tube, and the tube was then clamped in a vertical position and the lower end connected with a hydrogen generator. After all the air had been expelled, the tellurium was fused by carefully heating the tube up to a temper- ature just below dull redness. It was found that the tellurium did not stick to the glass tube if the fusion began at the bottom. When the tellurium had cooled just below the fusion point, the glass tube was shattered by throwing a fine stream of water on it so that the glass could be picked off without breaking the tel- lurium rod. Sometimes the tellurium could be pushed out of the tube without picking the glass to pieces. [16] A special electrode (Fig. 4) was used for sparking ammonium nitrate to get standard lines and also for making comparisons of tellurium with various solutions where solid electrodes could not be obtained. The electrode consisted of a glass tube (a) through which a platinum wire (b) with a gold tip (c). was passed. An- other gold rod (d) was brought into position above the gold tip, and the spark passed between the rod and the tip. Solutions of nitrates of substances whose spectra were desired were placed in the cup O), and they were drawn up the gold tip (c) and got into the spark so that their lines appeared in the spectra, in addi- tion to gold and air lines. Fig. 4. The spark was furnished by a condenser consisting of four plates prepared especially for this work by Dr. Dudley, using bakelite as the dielectric. The plates are about 40 centimeters square and 4.5 millimeters thick. The condenser was charged by an induction coil carrying a current of 2.5 amperes under a pressure of about 20 volts supplied by nine storage cells in series. [17] PLAN OF INVESTIGATION. 1. Since Koethner 1 found traces of copper, antimony, silver, gold, and arsenic in so-called chemically pure tellurium, it was determined to make a very careful study of the spectrum, in- cluding wave length determinations, of the tellurium purified in this laboratory to see if it was free from these elements. 2. The extraordinary results of Flint 1 by a process of fraction- ation led to the adoption of the following plan : The tellurium was to be fractionally precipitated from hydrochloric acid solution of tellurium tetrachloride by using hydrazine hydrochloride. The spectra of the several fractions were to be compared in order to note any changes in the spectra as a higher degree of purity was attained. A second investigation of these fractions not embraced in this paper, but carried on in this laboratory by Mr. Bowers under the direction of Dr. Dudley was to be made by determining the atomic weight of tellurium from the different fractions. The re- sults of the two methods, if harmonious, should afford a good basis for judging the merits of Flint's work and furnish additional evidence on the character of tellurium. 3. It was noted in reviewing Flint's work that he reported a small, amount of an unidentified substance in the final residues. The amount was too small to admit of thorough chemical investi- gation. It was our plan to' make a careful chemical study of the final residues and apply the spectrograph for the purpose of iden- tifying any unidentified residues or precipitates which might ap- pear. 4. The coincident lines in the spectra of tellurium, copper, and antimony, and of tellurium, thallium, and indium, were to be iden- tified by photographing their spectra one above the other. The wave lengths of these lines were to be determined by the com- parator method described below. THE COMPARATOR METHOD. The comparator is used to get the relative positions of the lines. In order to do this some line or series of lines must be chosen as a standard. For example, in the spectrum of gold there are three easily recognized lines, which read as follows: 66.000, 71.270, and ^oc. cit. [18] 73-6io. Having "set" the comparator by these three standards, the other lines are read in either direction. These comparator readings must now be converted into wave lengths. This is done by plotting a curve on coordinate paper in the following manner : The comparator readings of the easily recognizable lines in the copper spectrum are carefully noted and recorded. Their wave lengths are then taken from a table of wave lengths. The lines whose comparator readings are 32.080, 33.060, and 37.275 have the wave lengths 4062.9, 4022.9, and 3860.6, respectively. The comparator readings are now measured along the horizontal co- ordinate and wave lengths along the vertical coordinate. (See Fig. 5.) Then using as coordinates the comparator reading and wave length of each line e. g., 32.080, 4062.9 ; 33.060, 4022.9, etc. we locate a series of points through which the curve is drawn. To find the wave length of an unknown line, take its comparator reading and locate the point corresponding to this reading on the horizontal coordinate and there erect a perpendicu- lar, and from the point at which it cuts the curve drop another perpendicular to the vertical coordinate, and read off the wave length on the vertical coordinate. The error of this ^method is about 0.5 Angstrom unit for sharply defined lines. METHODS OF PROCEDURE. 1. A large number of spectra of the tellurium purified in this laboratory were photographed, and the wave lengths of the lines present were determined by the comparator method. Tables of wave lengths were then consulted to discover any lines indicating the presence of an impurity. The spectra of tellurium, copper, antimony, and gold were compared by photographing them one above the other. At first no impurities were detected. But by using heavy voltage on the induction coil and reducing the re- sistance in the spark circuit to a minimum a much fatter spark was obtained which brought out the two copper lines mentioned by Koethner 1 A3273-4 and A3246.8. In this connection it was noted that Watt's table of wave lengths gives these lines as 10 tellurium lines. They are not present in the spectrum of pure tellurium. 2. Approximately 135 grams of tellurium twice distilled in ^oc. cit. [19] 3BOO 4000 4100 33. 33 37 5- [20] hydrogen were dissolved in nitric acid and evaporated to dryness twice with concentrated hydrochloric acid to remove the excess of nitric acid. The tellurium tetrachloride which formed was dissolved in the least possible excess of hydrochloric acid. Twenty fractions of tellurium, approximating 6.25 grams each, were pre- cipitated from this solution by adding hydrazine hydrochloride. The general method of procedure was as follows: A solution of the hydrazine hydrochloride was added to the tetrachloride solu- tion ; and after standing overnight at a temperature of about 50 degrees centigrade, it was heated to boiling to complete the re- action. The precipitated tellurium was collected on a hardened filter paper (which had been previously treated with hydrochloric acid) and washed thoroughly, first with hydrochloric acid ( I to 2), then with ammonia-free water, and finally with absolute alcohol followed by concentrated ether. After the ether was removed by suction, the tellurium was carefully dried in an oven at about 75 degrees centigrade. The various fractions were preserved in glass-stoppered bottles. The temperature at which the reduction took place was varied somewhat. But so long as it was allowed to finish at boiling temperature it seemed to make no difference whether the hydrazine was added to a cold or hot solution except that the reduction proceeded more rapidly in a hot solution. There are at least two possible reactions when tellurium tetra- chloride is reduced by hydrazine hydrochloride. Their equations are: Te C1 4 +(NH 2 ) 2 2HCl = Te+N 2 +6HCl and Te Cl 4 +4 [(NH 2 ) 2 2HCl] = Te+2N 2 + 4 NH 4 C1+SHC1. The yield of reduced tellurium indicated that the reaction took place almost wholly according to the first equation. This reaction tended to increase the excess of hydrochloric acid present in the solution. But this tendency was overcome by the water intro- duced with the hydrazine, and in making the fourth reduction several grams of tellurium dioxide, resulting from hydrolysis of the tetrachloride, came down with the metallic tellurium. Each succeeding fraction was likewise accompanied by a considerable amount of the dioxide. This dioxide was washed into the filtrate with hot hydrochloric acid ( I to 2). Electrodes were made by the method previously indicated from the different fractions of tel- lurium and the spectra of the various fractions compared. Ex- [21] ceedingly careful comparisons of the first, middle, and last frac- tions were made. Two series were chosen i. c., fractions i, n, and 19 in the first series and 2, 12, and 20 in the second series. After several trials, almost perfect photographs were obtained of these spectra one above the other. There was no difference be- tween these spectra except that the two copper lines mentioned above came out in the last fractions. 3. The filtrate from the twentieth fraction was reduced to less than 3OOCC by evaporation, and the usual amount of hydrazine added, and fraction 21 was thrown down. It weighed 2.22 gr. The filtrate was then further reduced in volume and fraction 22, of 0.5 gr., was precipitated from the boiling solution by adding hydrazine. A twenty-third fraction consisted of a very slight precipitate, which was lighter in color and more finely divided than the preceding fractions. Fractions 21 and 22 were very difficult to fuse. Thinking that they might be mixed with the dioxide, frac- tion 21 was washed thoroughly in warm hydrochloric acid ( i to 2) , in which the dioxide is soluble. A very little was dissolved, but the remainder seemed as difficultly fusible as ever. It was kept at red heat for twenty-five or thirty minutes, while hydrogen passed through it, and it was finally partly fused. Fraction 22 was mixed with a part of fraction 20 and heated as was fraction 21. After long-continued heating, it was partially fused. The spectra of fractions 21 and 22 were compared with the redistilled tel- lurium and with the middle fractions i. c., 9 and 12. There was no difference except the copper lines in fractions 21 and 22. Fractions 21, 22, and 23 were then treated with nitric acid (sp. gr. 1.25). A brownish white residue remained, which was found to be barium sulphate with a trace of tellurium. The nitric acid solution was evaporated to dryness three times with concentrated hydrochloric acid, and a second residue (barium sul- phate) remained insoluble in hydrochloric acid. The hydrochloric acid solution of tellurium tetrachloride was treated with hydrogen sulphide. A reddish brown color resulted, and a brownish black precipitate formed. When the action seemed complete, ammonia was added to excess. At. first the mixture became milky, and a curdy white precipitate formed which completely hid the brownish black precipitate. This white precipitate was probably tellurium dioxide. The mixture then darkened and the precipitates went into solution. (There remained undissolved a small finely divided [22] black residue residue A). The solution was evaporated nearly to dryness and all the tellurium was precipitated as a mixture of metallic tellurium and tellurous sulphide, and some ammonium salts crystallized out. The ammonium salts were extracted with water, the tellurium mixture was then boiled with concentrated hydrochloric acid, and hydrogen sulphide was evolved. Tke me- tallic tellurium was then dissolved in warm nitric acid and the insoluble residue filtered out, dried, and treated with carbon bi- sulphide, which dissolved the sulphur. The remaining residue was soluble in nitric acid and was added to the above nitric acid solu- tion. This nitric acid solution was evaporated to dryness twice with concentrated hydrochloric acid and taken up in hydrochloric acid and precipitated with hydrazine as usual. The tellurium thus precipitated was very difficultly fusible* but electrodes were finally secured tellurium Z. The spectrum of tellurium Z was compared with 'that of pure tellurium i. c., fraction 8 and a number of barium lines were found in spectrum of tel- lurium Z. The two copper lines still persisted also. Tellurium Z was dissolved in nitric acid. A white residue remained which proved to be barium sulphate. The solution of tellurium Z was evaporated to dryness twice with concentrated hydrochloric acid and taken up in slight excess of the acid. The tellurium was precipitated by passing sulphur dioxide into the hot solution, and was washed, dried, and fused as usual. It was perhaps a little more difficultly fusible than the fractions 8, 9, 10, etc. The new electrodes, tellurium Y, were compared with the pure tellurium of fraction 8. The two copper lines A32734 and A3246.8 were found in tellurium Y. Otherwise the spectra were identical. The final filtrate (from fraction 23) was evaporated almost to dryness. It yielded several grams of a white crystalline substance which proved to be hydrazine hydrochloride. The crystals were removed and purified by recrystallization, and the mother liquors returned to the filtrate, which was then evaporated to dryness on a steam bath. A brownish residue remained which seemed to lack definite crystalline form, and had an odor suggesting organic mat- ter. It was digested thoroughly with concentrated nitric acid and evaporated to dryness three times over a low flame. The color of the residue was changed to a yellowish brown, and small bunches of octahedra crystals were present in it. The residue was digested [23] with hot water and the insoluble matter filtered out and dissolved in nitric acid (sp. gr. 1.25). It was found to contain considerable barium and traces of iron aluminum and tellurium. The water solution gave a greenish yellow crystalline residue rhombohedra and hexagonal pyramids. Hydrogen sulphide in an acid solution of these crystals gave a brownish color and finally a brownish black precipitate which responded to the tests for tellurium. It- was tested carefully for copper with negative results. The filtrate also gave doubtful indications of iron. A trace of barium was found to be present. The barium was removed from the entire residue and the solution evaporated to dryness. A greenish yellow crystalline residue remained behind which was very hygroscopic. It was dissolved in water and a few drops of hydrochloric acid and treated with ammonia in the presence of ammonium chloride. A white flocky, semitransparent precipitate formed which ag- gregated on boiling. On standing overnight the precipitate changed to a light brownish yellow color. The filtrate was evap- orated to dryness and heated till ammonium salts were driven off and a very slight brownish residue remained, tinged in two spots with green. The precipitate was thoroughly washed and dissolved in nitric acid, resulting in a slightly yellowish solution. This solu- tion unknown number i was concentrated and its spectrum photographed. It gave a number of calcium and copper lines and several faint lines which were not identified at this time, but later proved to be iron and silver lines. The solution was evap- orated to dryness, the residue converted into a chloride, and the presence of copper was indicated by the ordinary qualitative tests. The calcium was removed as oxalate in the presence of acetic acid. Ammonium chloride and an excess of ammonia were added until a blue color indicated that the copper had gone into solution. There was a slight precipitate similar to the precipitate whose spectrum we had just examined. This precipitate was thoroughly washed and dissolved in nitric acid and included in solution (un- known number 2) described below. Residue A (page 22) was dissolved by boiling with dilute nitric acid and treated with ammonia in the presence of an ammonium salt. A white flocky, semitransparent precipitate formed. It changed in color to a light yellowish brown on standing. This precipitate was thoroughly washed and dissolved in nitric acid and included in solution, unknown number 2. [24] The filtrate from residue A was treated with sodium hydroxide and the ammonia boiled off. A heavy white precipitate formed, which was filtered off and washed thoroughly. It dissolved in hydrochloric acid with effervescence. A portion of the. hydro- chloric acid solution gave a slight muddy color with hydrogen sulphide, and on adding ammonia to the solution saturated with hydrogen sulphide a slight blackish flocky precipitate appeared. Further examination showed that the heavy white precipitate was chiefly calcium, and that the black flocky precipitate contained a trace of copper. The calcium was thrown out, as the oxalate, from the entire hydrochloric acid solution, an excess of ammonia added, and the solution boiled. A slight white semitransparent precipitate formed which changed in color to a light yellowish brown. It was washed, dissolved in dilute nitric acid, and included in solution, unknown number 2. The spectrum of the solution of unknown number 2 was com- pared with that of ammonium nitrate and the wave lengths of the extra lines determined. These lines indicated positively the pres- ence of calcium, iron, copper, and silver. 4. The spectra of copper, tellurium, and antimony and of tel- lurium, thallium, and indium were carefully compared. Since we had only salts of the two last-named elements, and their lines did not come out well, their study was discontinued. RESULTS AND CONCLUSIONS. The spectrograph has fully justified the claims made for it by Koethner as a means of detecting faint traces of impurities in chemical substances. It has also proved very effective in identi- fying slight residues and precipitates. In Koethner's report of his spectrographic work he called attention to a "shift" in the extreme ultra-violet lines when the same spectrum was photo- graphed twice in succession, one above the other, on the same plate. This "shift" was investigated and found to be only an apparent shift due to an improper manipulation of the apparatus. Such a shift does not occur and is impossible with our new form of slit cover slide. The tellurium purified in this laboratory and testing C. P. by chemical methods was found to contain traces of copper, iron, and silver. Kahlbaum tellurium was also found to contain a trace of copper. And although we have been able to get tellurium free [25:J from all known impurities by fractional precipitation with hydra- zine hydrochloride, the evidence of the spectrograph indicates that we have not brought about any breaking down or separation of the tellurium into parts differing in properties. The. twenty fractions showed no variations in their spectra except the appear- ance of the copper lines in the last fractions. The study of the final residues has not developed any new evi- dence on the tellurium problem. In Flint's discussions of his final residues he mentioned a yellow and a green residue which he said suggested a possible contamination with iron and copper, but he could not find even the slightest trace of either by the usual tests. It was noted above that the residue from the final filtrate had a greenish yellow color, and, again, that the filtrate from which am- monia had thrown out a flocky, semitransparent precipitate left a slight brownish residue tinged with green. This greenish yellow residue was also carefully tested by the usual tests for iron and copper, and gave negative results for copper and doubtful indi- cations of iron. The spectrograph, however, showed the presence of both these impurities. Flint says further : "When an excess of ammonia is added to a solution of the green substance in hydro- chloric acid, the precipitate obtained by neutralization of the acid is not completely dissolved by the excess of the alkali. The liquid filtered from this throws out a black substance (apparently tel- lurium) when acidified and treated with stannous chloride. The precipitate which did not dissolve in trre excess of ammonia, when dissolved, after thorough washing, in hydrochloric acid, gives also a black precipitate with the same reagent." 1 The semitransparent precipitate which was thrown down from our final filtrate was also insoluble in an excess of ammonia; and when dissolved in hydrochloric acid, after thorough washing, threw out a black sub- stance when treated with stannous chloride. The filtrate from the ammonia precipitate, after acidifying with hydrochloric acid, was slightly darkened when treated with stannous chloride. From a consideration of these facts it seems possible and even probable that Flint's residues did contain iron and copper, but in such slight traces as to escape detection by a means less delicate than the spectrograph. Since the results of Flint were not confirmed b his method in . cit. [26] the hands of Harcourt and Baker, there is no keen disappointment that the results of the method set forth in this paper likewise do not harmonize with his results. The fact that the copper which came down in the last fractions was not removed by two subsequent precipitations one by hydra- zine hydrochloride, and the other by sulphur dioxide seems to argue for a large number of fractions as against single complete precipitations or a smaller number of fractions as in the processes of Gutbier 1 and Koethner. 1 The presence of barium and calcium in the residues is not re- garded as significant. The barium was from the hydrazine hydro- chloride, and the calcium was probably an accidental impurity or from the same source. After a preliminary comparison of the ultra-violet spectra of tellurium, copper, and antimony, it was decided that the coincident lines were not of sufficient importance to study them further. A careful study of the extreme ultra-violet spectrum of tellurium resulted in the discovery of a group of six lines of shorter wave length than any tellurium lines found in -Watt's tables, and no record of their previous measurement has been found. They are A2002.6, A200I.8, A2000.4, AI997.6, XI994.8, and AI993.8. It was also found that a number of strong lines given in Watt's tables as tellurium lines do not appear in the spectrum of our purified tel- lurium. These lines belong to silver, copper, and gold. In conclusion, the tellurium problem remains unsolved. We have mentioned three possible solutions namely: (i) Tellurium is an element, though abnormal; (2) tellurium is contaminated by an admixture of a higher homologue of tellurium having an atom- ic weight of about 214; (3) tellurium is, like didymium, a mixture of two substances differing but little in atomic weight and remark- ably similar in properties. We have only added another link to the chain of evidence reach- ing back over forty years of research and pointing almost uniform- ly toward the elementary nature of tellurium. However, the writer is prone to believe that a different answer will be forthcoming sooner or later. The higher homologue admixture does not seem feasible for the following reasons : If this higher homologue dvitellurium, has an atomic weight of 214 and the correct atomic ^oc. cit. [27] weight of pure tellurium is, let us say, 125.5, there would be pres- ent only about two and one-fourth per cent of the dvitellurium. It is believed that the above-described rigorous treatment of 135 grams of material containing only two and one-fourth per cent of a substance as different from true tellurium as dvitellurium must be from its position in the periodic table would have brought about sufficient separation to have enabled us to detect it by means of the spectrograph. On the other hand, if tellurium is, like didymium, a mixture of nearly equal parts of substances differing but little in atomic weight and remarkably similar in other properties, we should not expect the spectrograph to reveal this fact to us without more complete fractionation. And the writer believes, though the be- lief may not be well founded, that this third "possible solution" suggests the direction which the future investigations of the tel- lurium problem should take. THE SPARK SPECTRUM OF TELLURIUM. We give below the wave lengths of the lines of the spark spec- trum of tellurium as we have found them ; also previous measure- ments by Huggins 1 and by Hartley and Adeney. 1 It was stated above that a number of lines belonging to copper, silver, and gold were given by Hartley and Adeney as tellurium lines. The wave lengths of these lines, with the elements to which they belong, will be given opposite the corresponding lines in Hartley and Adeney's 1 table. The intensities range from i, for lines easily visible, to 10, for the strongest lines in the tellurium spectrum, o is used for lines just visible. An n denotes nebulous, a line not sharply defined; s denotes sharp; b denotes broad, the reading of the heaviest part being given ; sn denotes a nebulous line which is rather sharply defined. After some of the lines an A will be seen followed by a question mark, indicating that it is possible that this line is an air line. 1 Watt's "Index of Spectra," p. 136. [28] Other Elements Other Elements HUGGINS* & HAHT- OUR Present in Hart- HARTLBY & OUR Present in Hart- Tellurium. ADBNBY. MEASUREMENTS. ley & Adeney's Tellurium. || If Ijj Is Wave *> Wave Wave t Wave Wave *.. 2 Wave Length. S i Length. " r: Length. 1 Length. ~ Length. * Length. S 1 S IS 1 Is I - Bt a a a Hugging. 4547-4 3 n 6600.0 i n 4544.0 i b 6645.0 6431.0 6366.0 4 IOS I S 6641.5 66045 6481.6 6433-4 6363-5 2 n i n i n 4 sn 2 n 4487.0 44So.o 4436.0 4400.0 2sd 2sd 2Sd 2sd 4489-4 4481. S 4436.2 4102.4 43900 3" 4 n 3" 2 S A? 6347.0 6290.0 I n 28 6289.5 2 n 4378.0 4364.5 2sd 2sd 4377-4 4363 s 5 s 6243.0 6228.0 3" 38 6242.4 6227.6 2 n 2 n 4353-0 4324-6 2Sd 4356.2 4326.8 6160.4 i n 4301-5 6 sd 4302.6 5 s 6042.0 6010.0 5995-0 6sd 6sd i n toS^.o 6043.0 6010.0 5993-6 i n 3 n 2 n i n 4292.7 4287.3 4274.4 4*59-8 4 sd eld 6sd 4294.6 42890 4276.0 4261.8 3" 3" 4sn 7 sn 59700 IO SC 5970-4 5sn 4222.1 6sd 422 r.o 58 59340 Ssc 5932-0 4190.2 3 s 5854-0 *-sf 4 sc 4 sd 5850.0 3" 4180.7 4170.3 2Sd 4 sd 4181.4 4172.0 Snb 2 nb *5Sol6 4 no 4 nd 5825.2 5804-4 2 n t n 4162.5 4I25-5 3" 3" 57400 10 SC 28d S76I.5 5753.8 5742.2 6 sn 2 n 4119.7 4073.7 4061.3 4 sd -s.l 6sd 4119.8 4073.8 4061.5 7sn 4 s A? 57o8.o 10 SC 6s 4 sn A? 4054-2 4048.3 6sd 4 sd 4053-4 4048.6 4 sn 3" 5646.0 IOSC 5650 5 7sn 4011.6 i n 56180 4Sd 5618.8 2 sn 4006.0 Ssd 4006.5 4 8 5575-0 Ssc 5575-0 6 sn 3985.2 3 n 54S6.0 6sd 5486.2 5 sn 3983.8 6sd 3982.2 2 n 5476-0 6sd 5476.0 4sn 3976.8 2 n 5447-0 Ssc 5449.4 6 sn 3970.2 > n 5409.0 5366.0 48d " SC 54io.5 5369.5 4 sn 3968.6 394S.O 6sd 6sd 3947-5 3n 396S.3 Ag 5309.0 6sd 5310.8 3 3932.5 2sd 3932-0 3" 5298-0 2sd 5299-0 2 S 390S.7 3nd 3907-8 i n 5252.4 3" 3870.0 i n 524L5 2 n 3841.3 2sd 3842-5 6 sn 5222.0 Snc 5230.0 i n 3805.5 i n *5l/2.2 2sd 5174.5 4 n 3803.0 4 sd 3801.5 i n *5I52.2 6sd 5I5I-4 i n i79X9 2sd 3797-4 3" 5038.0 2nd 4 sd 5 '33-6 5062.0 5038.0 2 n I n A? 377^0 3771.0 4 sd 4sd 4 sd 3789-0 3776-4 2 n 2 n 377'. i Au 4922.2 i n 3765.0 4 sd 3765-0 2 n * 4 8 9S . I 2nd 2 n 4" 3759-0 3754-0 4 sd 4sd 3S 3759-0 3754-8 Au Au 4$S6.o 3 n 3750.0 3 n 4866.0 4 nd 4868.0 Ssn 3737-2 4n 4842.8 3 n 3735.5 Ssd 4832.0 4785-0 2nd 2nd 4835-0 4785.5 4sn 3736.2 3716.0 Ssd 4 sd 3726.0 2 n 4769.0 4 n 3713.5 i n 4737.1 i n 3709.6 i n 4731.6 4 n 3708.8 o n Hartley & 3698.7 4 sd Adeoey. 3683-3 4sd 4707.5 4693-0 4 sd 4sd 4706.8 4sn 5" A? 3676-7 4 sd 3679.0 o n 4664.0 i n 4665 o 3 n 3670.4 4 sd 3671.2 o n 4652.0 i n 4656 2 3 n 3656.4 4 sd 4602.0 2 S.I 46042 5s 36500 3 s 4599-0 i n 4S70-I 3649.2 / 3644-3 f 6sd 3 Wave . Wave 1? 8 Wave i S Wave Leugth. a <5 Length. f| Length. I Ltngth. | Length. % a Length. 1 ij |g S > g IS a K I = -H 36450 3 s 3168.5 4 sd 3636.3 4 sd 3160.4 3 n 3626.7 3617.0 6sd - 3627.0 3617.4 i n 4 sn 3I5S.4 3154.1 2sd 4 sd 3I53-4 2 n 3611.0 4 sd 3611.2 2 n 3'45-7 4 sd 3601.7 4 sd 45 3601.1 Au 2Sd 3132.4 45 3599-6 4 sd 3129.0 i n 3594-5 3589.4 4 sd 4 sd 3593-0 3584.0 3" 2 n 3124.7 3"9.5 3107-5 2Sd 4 nd 6sd 3119.6 3107 8 3" 355 J -6 Ssd 3S5I.8 6 sn 3098.7 4 sd 3098.2 2 n 3541.8 4 sd 3s 3541-7 Au 4 sd 3096.4 4 n 3533-1 4 sd 5 sd 3533-7 Sb 3088.0 4 sd 3090.0 3 n 3522.0 4sn 3072.7 6sd 3073-0 5". 3520.3 Ssd 3520.3 Sb 3063-2 2Sd 3063.0 8 2sd 3052.8 2Sd "3052.9 411 j Ssd 34968 6 sn 3050.5 3 n 7 2sd 3484.0 3sn 3046.0 Snc 3047-4 8 n 3480.8 4 sd 3480.0 2 n 3022.1 2 SC 3023.2 4 n 3474-4 2sd 3475-0 3sn 3016.6 Ssd 3018.0 6n 3465-5 4 sd 3466.0 i n 3012.1 4 sd 3012.0 4n 3457-6 1 4 n 30055 4 n 3456.0 Ssd 3456.0 j 4 n 3004.1 4 sd 3004.2 3 n 3450-4 26d 3 s 3450.4 Cu 2996.4 4 sd 2997-0 3" 3442.8 5sn 2988.8 4 sd 2989.0 2 n 3441.2 Ssd 2976.2 4 sd 2977-4 2 n 3423-5 o n 2975-5 4 sd 2976.0 3 s 3422.2 4 sd 2973-1 2sd 2973.8 3s 4sd 2sd 34H-7 Sb 2966.1 Ssd 2967.4 6 n 3407-5 Ssd 3407.8 6 nb 2960.3 2 SC 2960.4 2 n 3382. 4 IO SC IO SC 3382.9 Ag 2956-3 2sd 2957.0 3 n 3374-1 3362.4 4 sd Ssd 3374-5 3362.8 3" 6n 2950.6 2948.8 2sd 2Sd 2950.8 2948.8 2 n 2 n 3352-1 6sd 3352-0 3" 2945-3 2sd 2946.0 i n 3340.8 i n 2940.8 Ssd 2941.4 6sn 3329.0 6sd 3329-I 4 sn 2937-7 4 sd 33227 4 sd 3322.8 2 n 2932.5 4 sd 2932 s 2 n 33'5-S 4 sd 3316.0 2 n 2928.1 2sd 2929.8 2 n 3307-I Ssc 3308.0 2 n 2923.4 4 sd 3302.2 2 n 2918.9 2sd 2919.4 5" 2 n 2905-9 2 sd 2906.8 3289.6 2 SC 2901.9 4sd 4 s 2002. p Ag 3283-0 5sn 8nd 2895-4 9 sn 1 3280.0 ) 10 SC 3281.2 5sn 10 SC 3280.8 Ag 2893-3 2877.4) 2873.6 ; 6sd 2sd 2sd 2893.8 4 n 7sc 5 s 2877.1 2873.6 Sb Ag '. 3278.4 3 n 2867.7' 8nd 2868.8 8 sh 3269.5 3 n 2859:9 6sd 2860.6 4 n 3266.8- 5" 2857-0 8nd 2857.9 8 sn 3264*6 j 2sd 2844.9 28400 6sd 6 sd 2846.4 2841.0 4 n 6n 3261.5 3 n 2836.9 2Sd 3256-3 Ssd 3257.4 5sn 2834.4 2sd 2835.0 3sn 3252.4 5 sn 2823.2 6 sc 3250.8 4sd 2818.8 4 n ; 3246.8 IO SC TO S 3247.6 Cu 2815-3 28d 3242. i 4 sd 2813.0 2Sd 2812.0 2 S 3234-2 1 4 sd 3232-8 4 nb 2799.1 4 sd 3229.4 f 2sd 2795-5 4sd 27970 4 n 3221.8 3217.6 4 sd 4sd 3aao.o 3" 2791.9 Snd 2793.2 2778.0 8n o n 3213-3 4 sd 3214.2 3 n 2776.8 o n A? 3210.4 2 sd 3211.6 3 n! 2768.6 6sc 2769-5 8s 3192.2 4sc 2766.5 6sd 2767.0 2 n 3188.1 4sc 3188.3 3 n 2766.0 4sc 3-85-0 4 n 2758.8 On 3183-7 2sd 2756.0 2 SC 3174-4 4 sc 3I7C.2 5s 275 '-5 2 nd 2751-8 o n [30] HARTLEY & ADENEY. OUR MEASUREMENTS Other Element* Present in Hart- ley ft Adcney's Tellurium. HABTLI ADEN Other Elements Present in Hart- ley ft Adeney's Tellurium. tY. Wave e . Wave Is Wave Ware 1| Wave 1| Waqe Length. jl Length. f 1 Length I I Length. P Length. }1 Length. j 2745.0 4 sd 2745-5 Sn 2490.8 2 nd 2 S 3490.4 Au 2743.0 4 8d 2488.7 2sd 2 S 3488.' Au 2739-5 2738.0 4 sd 4 sd 2740.0 27370 i n 2485.3 2480.9 2 nd 2sd 2480.6 3S 2 n 2485.7 Ag 2733.2 o n 2479.6 2 nd 2724.5 Ssn 2476.7 2 nd 2477.8 i n 2723.2 2 nd 2473.2 6sc 2474.3 i n 2720.7 2Sd Ss 2473.7 A ~ 2718.0 2713.0 ) 2710.2 f 2702.3 2sd 2sd 8nd 2sd 2711.4 2703.2 6sc Sn 2717.9 Sb 2469.0 2462.0 2460.2 2452.8 2 nd 4 nd 4 nd 2 nd 2469.8 24S3.S Ss 4s i n 2462.6 2460.0 5! 2700.3 f 2696.6 2 sd 6nd 2697.5 10 Sn 2701.3 Cu 2447.8 3444-3 6sd 2 nd 2445-0 8s 2 n 2447.7 Ag 2694.1 6nd 2695.4 2441.7 2 SC 6s 2441.9 Cu 2690.2 2sd 2691.8 3 n 343S.O Ssc 2438.6 4 n 3688.2 2sd 2689.0 o n 2433.5 i n 2683.2 2nd 2683.8 4 n 24320 2 nc 2431.8 6 sn 2679.8 2 nd 2680.0 2676.8 4n i n 2428.2 2 nd 28C 7s IOS 2430.3 2428.1 Ag Au 2674.6 2 SC 2sd 2674.0 Sb 2426.7 2 nd 2426.4 4 n 2666.0 4 sd 2666.0 i n 2425.0 4 nd 2424.7 Cu 2661.6 3 n 3423.8 i n 2659.4 2bd 2660.0 4n 2420.3 2 nd 2420.0 4 s 3657.1 4 nd 3656.5 2 n 2418.5 2 nd 2418.? 3" 2653.2 i n 2415.8 i n 2648.7 2647.0 2 nd 2 nd 2649-5 2647.6 4n 24J3.3 2411.4 Ssc 6sc 2411.8 IO S 4 n 34133 Ag 2642.3 2637.0 3634.7 2 nd 2sd 6nd 2642.5 2637.5 2635.4 i n 4n Sn 2403.7 2400.0 6nd "SC 2403.7 2397.0 i: i n 2400.5 Cu 2630.5 2 nd 2631.3 5 n 3393.0 i n 2627.8 4 sd 2628.2 2 n 3392.8 4 nd 2392.6 i n 2624.3 2621.4 4 sd 4sd 2635.0 2622.5 3n i n 2390.7 3386.3 4 nd 10 nc Ss IO S 2391.0 Ag 2617-4 2 SC 2S 2617.6 Au 33S3.8 10 nc 2383.8 10 s 2613.7 4 sd 6s 2614.3 A* 2377-0 3 nd 5 s 2377-1 Cu 2611.3 4 sd 2612.3 i n 2375.3 3 nd 2375.0 3 n 2604.4 2 nd 2605.4 4 n 2370.3 Ssc IO S 23/0.6 Cu 2599.4 2sd 2599.0 4n 2367.S 2 n 2598.1 2sd 9sc 2597.5 Sb 3364.7 4 nd IOS 2364.8 Au 25940 2sd 3362.8 4 nd 4 2362.8 Ag 2590.1 2585.0 2 nd 3 nd aSSS.I 3 n 2359.8 4 nd 10 j 2359-9 1 2359.7 Fe? 2580.1 2578.0 2 nd 2 nd 2578.6 2580.6 Ag 2358.6 2357-0 6sd 4 nd 2358.6 23574 2 n 2577.0 3 n 2352.0 7 gf| 2574.8 4 sd 2575-0 i n 235'- 7 2 nd 235I-I 3sn 2572.4 4 nd 2572.4 2 n 23443 2 nd 2344.5 2564*1 2 nd 3 n 2567.2 2564.6 on on 2340.3 3336.8 2 nd 2 nd 3$ 3" 2558.7 2 nd 3559.5 2 n 2332.0 Ssd S s 2332.1 Ag 2549.7 2 nd 2550.2 3 n 2327.6 3 n 2543.7 2536.8 3533.8 6sd 2 nd 2sd 2543.5 i n 2 S 6 2536.7 2533.6 Ag Au 3325-5 2321.0 Ssd Ssc 2320.4 Ss Ss i n 2325.8 3321.1 A| 2528.3 Ssc 3 nd 2530.7 8s 2526.9 Cu 2317.8 Ssc 2316.8 Ss i n 23I7.9 Ag 2525.6 2 sd 3s 2525.2 Cu 23:0.1 2 nd 2310.2 2 n 2523.1 i n 2308.8 2 n 2517.8 i n 2303-7 2 nd 2303.1 Cu 3511.7 i n 2301.1 2 nd 2300.8 i n 2505.2 6sd IO S 95 2506.6 25064 Cu 2297-5 2nd 2299.8 2297.3 i n 2 n 2502.7 2Sd 3* 2503.4 Au 3295.0 6nc 6s 2295.3 3u 2500.0 Ssn 2291.8 2 nd 4 s 2291.7 Cu 2498.6 6nd 2497.8 Cu 2288.6 2 nd 2288.5 2 n 2491.3 2 SC 2492.0 3sc 22806 6r.d Ss 2281.3 Ag [31] Other Elements Other Element* HAHTLJEY & OUR MEASUREMENTS. Preient in Hart- HAKTLBY & OUR MEASUREMENTS. Present in Hart- AliEMY. ley & Adeney's ADNY. ley & Adeney'B Tellurium. Tellurium. 1 i w . 3 9 . 1-1 Wave Length. fl Wave Length. g Wave Length. i Wave Length. Jf Wave Length. II Ware Length. i IS a JJ 1 N | S 1 s I 2277.2 2275.7 6nd 6nd 6s Ss 2277.3 2275.8 Ag Ag 2159-7 2149-7 2 nd 2 nd 2160.0 6 sn 45 2149.1 Cu 2272.5 5" 2147.8 2 nc 2147.6 7 n 2266.2 6nc 2266.0 7sn 2146.7 2 nd 2264.2 2 nc 2264.2 Cu 2143-3 6 sn 22604 6nc 2259-5 S sn 21427 2 nd 2142.6 3sn 2256.6 6nc 2256.2 7sn 2136.5 2 nd 3s 2136 I Cu 2250.0 2248.0 6nd 6sc 2251.0 2 n 6s 7s 2250.2 2248.0 Ag Cu 2135-0 2125.5 2nd 2 nd 2 S Ss 2134-5 2125.3 2125.3 Cu Au Cu 2247.3 2243-3 6nc 6 be 7s 2247.6 2243.8 Ag Cu 2122.5 2 nd 2121.4 3s 3" 2122.4 Cu 2240.7 2nd 2240.2 3" 2119.8 3" 2238.2 3" 2119.0 2 nd 4s 2II9.3 Ag 2231.3 2nc 2230.9 Ag 21I6.S 2 n 2230.3 2 nc 3 D 2230.5 Cu 2116.3 2 nd 2 S 2116.3 Cu 2229.0 2 nc 3s 2228.7 Ag 2113.3 2 nd 3 s 2112.3 Ag 2226.8 2 nd 2227.4 2 n 2 S 2II2.C Cu 2223.2 2 nd 2223.2 i n 2110.5 2 nd 9s 2IIO.8 Au 2219.3 6 be 6 s f 2219.6 \22l8.8 Cu Cu 2108.4 2103.6 2 nd 2 nd 2109.2 2 n 2 S 2103.3 Cu 2216.0 2 nc 2216.3 3" 2100.2 2 n 2IOO.8 i n 2215.0 2 n 20822 7n 22II.2 6nd 5 s 22II.I Cu 20SI.2 2 n 2209.5 6nd 22O9.O 6 sn 2078.5 2 nd 2 S 2079.0 Cu 2207.4 2 n 2O72.O 2 n 2202.8 2 nd 3" 2202.3 Ag 2050.8 2 nd 22OO.I 2 nd 3 s 22OO.I Cu 2039.2 2 nd 2196.5 2192.2 2189.7 2 nd 6nc 6nd S.s 2196.8 2192.4 2189.9 Cu Cu Cu 2032.7 2 nd j 2OO2.O 2 S 2b 3 sn 2037.3 2031.3 Cu Cu 2l86.9 2 nd 2186.8 4sn (2001.3 4sn 2lS2.O 2 nd I S 2l8l.3 Cu 2OOO.O 2 sn 2179.2 6 nc 5s 2179-3 Cu I997.S i sn 2175-3 2 nd 3I7S-Q J '994-5 3sn 2167.2 2 nd 2167.4 75 1 1993-7 i sn 2165.7 2 nd 4s 2I66.I Ag 1321 SUMMARY. 1. The quartz prism spectrograph has proven a very efficient instrument both for detecting traces of impurities and for wave length determinations. Its efficiency was greatly increased by our modification of the slit cover slide. 2. The occasional shift of some of the ultra-violet lines in Koethner's work has been accounted for, and it has been elimi- nated by the use of our new slit cover slide. 3. The entire spark spectrum of tellurium has been measured. 4. The tellurium purified in this laboratory by fractional precipi- tation with sulphur dioxide, by fractional crystallization of the basic nitrate, and by twice distilling in an atmosphere of hydrogen has been found to contain silver, iron, and copper. 5. It has been shown that Khalbaum tellurium contained a trace of copper. 6. Six new tellurium lines have been found having wave lengths shorter than any tellurium lines recorded in Watt's tables. 7. It has been shown that the tellurium of Hartley and Acleney contained copper, silver, gold, and probably antimony. 8. It seems very probable that Flint's colored residues contained copper and iron. 9. Fractional precipitation of tellurium from a hydrochloric acid solution of tellurium tetrachloride with hydrazine hydrochloride has not resulted in any decomposition or breaking -down of the tellurium. 10. We have obtained more than one hundred grams of tellurium free from all known impurities. PAT. JAN. 21 ,1908 69SV1 UNIVERSITY OF CALIFORNIA LIBRARY