ANALYTICAL EDITION
JULY 15, 1939
TABLE11. FRACTIONATION OF MIXTURERICH IN YTTRIUM GROUP Weight
Mean Atomic Weight
Grams
Original Insoluble fraction Soluble fraction
100 55.1 35.2
117.1 132.4 104.4
Furthermore, in the classical double sulfate method, a larger amount of sodium sulfate is present in the insoluble fraction and, therefore, this fraction requires more treatment than is necessary when the sulfamate method of separation is used. These are important factors where large quantities of rare earth materials are to be separated into lanthanum and yttrium groups. This new procedure is also of distinct technical interest because of the availability of sulfamic acid (1) as a new industrial chemical a t a moderate cost. PREPARATION OF SOME RAREEARTH SULFA MATE^. I n view of the fact that the method of fractionation described above involves the use of rare earth sulfamates in solution, it was considered desirable to isolate the sulfamates of several typical rare earth metals. The following procedure was used.
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Sulfamic acid solution was added t o an excess of the rare earth oxide. The mixture was stirred for approximately 0.5 hour and then heated on a steam bath for 1 hour. The reaction mixture was then filtered and concentrated to a small volume on a steam bath. Crystallization of the sulfamates from aqueous solution was ineffective because of their abnormally high solubility in water. Consequently, the concentrated aqueous solutions were gradually dehydrated by shaking with absolute ethanol. Continued treatment of the alcohol-insoluble solution (gummy mass, or solid) with fresh alcohol eventually yielded a powdery material. The sulfamates of lanthanum, neodymium, samarium, and yttrium were prepared in this manner. Obviously, the amount of water of crystallization in the compounds could have varied considerably. Consequently,
the products were analyzed for their sulfur and rare earth metal content and the ratio of per cent of rare earths to per cent of sulfur was calculated in each case and compared with the theoretical ratio, assuming the starting materials to be 100 per cent pure. The analytical data given in Table I11 indicate satisfactory concordance between found and calculated values. The rare earth sulfamates listed in Table I11 are insoluble in absolute ethyl alcohol, methyl alcohol, acetone, dioxane, pyridine, and liquid ammonia. They decompose slowly a t 100" C. to give the corresponding sulfates. In hot aqueous solution the rare earth sulfamates seem to undergo slow hydrolysis. TABLE 111. SULFAMATE VALUES Per Cent SUIFormula fur Found La(S0aNHz)a.XHzO 20.26, 2 0 . 1 4 Nd(SOaNH*)3.XHzO 20.14, 2 0 . 0 4 Sm(S03NHz)a.XHzO 19.71, 1 9 . 7 6 23.49, 2 3 . 5 4 Y(80&"1)9.XHzO
Rare Earthper c e n t Sulfur Ratio x = Rare Earth Ob- Calcu- Moles Metal Found tained lated H20 2 9 . 1 4 , 2 9 . 3 2 1 . 4 4 1 . 4 4 2-3 3 1 . 0 5 , 3 0 . 9 6 1 . 5 4 1 . 5 0 1-3 3 1 . 4 9 , 3 1 . 6 6 1 . 5 9 1 . 5 6 2-3 21.21, 2 1 . 1 6 0 . 9 0 0 . 9 2 1-3
Acknowledgment The authors wish to acknowledge their indebtedness to the Grasselli Chemicals Department of E. I. d u Pont de Nemours & Company, Inc., for technical sulfamic acid and to B. S. Hopkins for use of the rare earth materials.
Literature Cited (1) Cupery, IND. ESG.CHEX.,30, 627 (1938). ( 2 ) Gahn and Berzelius, Schweigger's J . , 16, 250 (1816). (3) Gibbs, Am. Chrm. J . , 15, 546 (1893). (4) Urbain, Bull. SOC. chim., 15, 347 (1896).
A Continuous Extraction DiEusion Device MARTIN MEYER Brooklyn College, Brooklyn, N. Y.
A
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S I M P L E and continuous diffusion extraction apparatus, for use where complete extraction is unimportant, is shown in the diagram. It requires a 12-inch section of 3- or 4-inch glass tubing, a Gooch crucible or similar device, a test tube equipped with an internal siphon (which leads into the outside solution, not into the Gooch crucible), a calcium chloride tube packed with cotton, glass tubing, stoppers, a test tube, connectors, and stopcocks as shown. The solvent is placed in the suction flask and the material to be extracted in the crucible. The apparatus is then closed and the vacuum from an ordinary aspirator is turned on. Operation is controlled and may be adjusted by changing the level of the right-hand tube a t A . The effectiveness depends upon the difference in levels a t this point. This device may be made to operate a t any desired temperature by removing the vacuum and heating the suction flask. It will then work on pressure instead of vacuum and breathing can be obtained a t the top. The water test tube is designed to compensate for evaporation where the solvent is aqueous, and the cotton removes dirt from the air. The test tube with the siphon in the glass column prevents splashing as the liquid sucks up.
VACULIM f-
