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tion should be conducted iii cold dilute solution in the presence of a quailtity of a strong acid considerably more than equivalent to t h e oxalate added. We are greatly indebted to t h e M'elsbach Light Company for some of the rare earth material. C A M B R I D G E ,MASS January 20, 1 y 8 .
YTTRIUM EARTHS. [FIRST PAPER.] HY V I C T O R L E N H E R .
Received December 28, 190;.
The methods which we have a t our disposal for the separation of the earths of the yttrium group ma\- be classified under the following heads: ( I ) Fractional precipitation ; ( 2 ) Fractional crystallization ; (3) Fractional decomposition of such yaks a s the nitrates by heat. Under fractional precipitation, we have methods which depend largely on the differences in basic properties. such a s the fractional precipitation by ammonia, magnesia, ctc. 'I'hc speed by which separations are cffected by use of this principle depends largely on how quickly the system can be brought into equilibrium. In the methods of fractional crystallization we must depend necessarily on the differences in solubility of various salts and a s a rule with the mixtures which are found in the rare earth minerals; the solubilities of a given salt of the \.arious metals are not widely different. On this account separation by the crystallization of the nitrates or double nitrates is not rapid, while with the chroniates accurate conditions must be ohserved, in which case this method gives splendid results. The decomposition of tht. nitrates 1)y heat is slow, but can, by patience, be carried out with success. 'l'he basic nitrate method of Welsbach' which can be applied to the yttrium group is a combination of this method and that of fractional precipitation. I t is inore rapid and successful than either method alone. The successful usc oi any of the methods for separating the metals of the !ttriurn group depends largely on the ratios of the various constituents present in t h e mixtures, as well a s on the character of the elements to be separated. We note, for example, that Dennis and Dales? in their study of the yttrium earths from sipylite find that magnesia, as a precipitating agent, causes little change in the atomic weights and absorption spectra, while James8 was more successful in using this method Monatshefte, 5 , 508. a
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a
Ibid., 29, 49 j.
428.
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573
on gadolinite earths. James used the nitrate solution while Dennis and Dales used a chloride solution. The author in working in a nitrate solution with yttrium earths from monazite has found t h a t various fractions acted quite differently toward magnesia, some showed marked differences in atomic weight and absorption spectra after treatment with magnesia, while others showed little change. I t has been observed, moreover, that in order to work this method with a n y appreciable degree of success the magnesia must be freshly ignited. The various degrees of success with different methods can also be illustrated by the Welsbach method’ of crystallizing the oxalates from an ammoniacal solution or b y the James method* in which the “oxalate-carbonates” are crystallized from an ammonium carbonate solution of the oxalates. This method with gadolinite earths in the hands of James yielded first yttrium and successively fractions with higher atomic weight t o ytterbium. I n the author’s hands, it has worked similarly with the yttrium earths from samarskite but on applying the same method t o certain oxalates from monazite, atomic weight determinations showed t h a t the elements with heavier atomic weight appeared first while the more soluble portion yielded fractions whose atomic weight was far below the more insoluble portions. In other words, we here have the same method producing opposite results with different mixtures of earths. From time t o time, it has been proposed t o use salts of organic acids. The oxalates can be crystallized from either ammoniacal or ammonium carbonate solution, yielding a fairly rapid method of fractionation, or the oxalates can be crystallized from nitric acid solution yielding fractions of different atomic weights. The ethyl sulphates and the acetyl acetonates have been used by Urbain and others a s means of separation in this group. The formates have been repeatedly used for fractionations. Salts of a number of organic acids have been prepared, but little has been done in the application of the derivatives a s means of separation. Such salts a s the tartrates, citrates and succinates have been prepared, but little has been attempted in the way of separation. The tartrates and citrates of the yttrium earths appear a s white gelatinous precipitates when a neutral salt of potassium, sodium or ammonium is added t o a solution of the yttrium salt. In a similar manner, insoluble derivatives are formed with neutral salts of fumaric, maleic, tartronic, malic and malonic acids. The neutral succinates of the alkalis or ammonium deport themselves in a very interesting manner with the neutral nitrates of the yttrium earths. When neutral ammonium or sodium succinate is added to a neutral nitrate solution of the yttrium earths and the solution allowed t o stand, Monatshefte, 27, 935. 1
THISJOURNAL,
29,495.
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I,ESHE:K
divided cr!.stallinv prvcipitatc of t h e succinates appears. 'Chis insoluble precipitate forms slowl!.. in fact, in the cold a few hours are a r y to insurc complete precipitation. On tlie other hand, when the solution is liot or boiling, coiiiplctc precipitation is effected in niuch less t i m e , from ten minutes to half an hour k i n g sufficient time for complete forniatioii of tlic insolulile succinates. 'rhe ready formation or this finely divided precipitatv and the fact that the reaction is f a r iron1 instantaneous appears to 11s as proniising t o lie a satisfactory method for fractionation. 'l'he fact that it forms ;is slowl~-as it does, \yould indicate that there sliould lie plent?. of tinie l o r equilibrium to ] ; e estalilishcd a n d the physicxl c1iaractc.r of the salt and its insolubilit!. vllablcs it to lir. yuickl?. filtered a n d rcadil!. w~islied, 'l'liat the yttrium earths lorn1 succiriatcs was shown by Herlin in 1835. I lie shon-cd that with sodium succinate tile !.ttrium earths I'orni a fine crystalline powder. 1;keberg in r 8 m 2 tliought that the J t t r i u m earths \yere not precipitated I)! thc alkaline succinatcs while beryllium ivxs, jvhich was contrary to the i-estih found b>- Herlin and to the work oC C l ~ v ca n d I-10glund3 who showed that arnmoniuni succinate precipitates \.ttriuiii hut not crbiuiii fro111 tiitrate solution, but out of a iriisture precipitates both. 111 tht, thorium ceriuni group, 13erzelius showed in 1 8 2 9 ~the forniation of aii insoluble succinate of thorium. This reaction has been later studied by E;aufniann5 and Schilling.6 The use of a n alkaline succinate 1135 l ~ c e nrecoiiinic~ndcda s a nieans of scqaration of iron from the gadolinite earths b y Cadolin. I-auquelin, 13erzelius, Berlin, and Hermann, after I
