1060
l',C. VOSRURCHAND RUTHSTOCKDALE McC~u~rr
Vol. 65
Summary of SiOz (or other oxides) in Bi203. However, the lattice constant of -y-Biz03(10.245 A.) was found 1. Pure Bid& has been found to crystallize in to be larger than that of the impure phase (10.090 a t least three forms. k . ) formed by fusing mixtures of Bi20aand SiOz. 2. The tetragonal, fi, form has been found to Hence, the latter phase would have to represent represent a high temperature modification with rea substitutional type of solid solution--if i t were a spect to the monoclinic, a,variety, and the transisolid solution a t all- -inasmuch as in an interstitial tion temperature has been determined as 710". type of solid solution "solute atoms are crammed 3 . A new form of Bi203(Y-BizOa) has been disin between the solvent atoms and as a result al- covered and found to be body-centered cubic ; ( t o ways cause an enlargement of the unit cell re- 10.243 A. No region of stability between SS* a r i d gardless of the size of solute atoms." Moreover, the melting point has been found for this phase. the possibility oi this phase reprcselltirlg a sub4. A new method of preparing P-Bi203and it stitutional soiid solution is rendered unlikely by method of preparing r-Bi20shave been described. the very unfavorable size factor for the replace3 . Evidence has been cited to indicate that it ment of Bi by Si atoms arid by the lack of varia- is hardly to be expected that the cooling curve tion in lattice coilstant with composition exhibited technique applied to molten Biz03 could furnish by the Bi203-Si02 fusion products. The possi- any indication of a transition occurring in the solid bility that this phase represents a compound be- state. =Z more likely interpretation of Guertler's tween Bi203aiid Si02 (or other oxides) seems more cooling curve evidence for the existence of two favorable aiid a. likely composition of such a com- polymorphic forms of Biz03with a transition tempound, Rle"'2Biz4Ci3s or ;1Lile'v?Bi~40~0, has been perature a t i04' has been proposed, namely, that advanced by Si!16n,'i based mainly upon struc- contamination of the molten oxide by the contural considerations. The most direct attack taiiiing vessel led to a two-component system. upon the problem would be a determination of the 6. The impure "body-centered cubic'' and "simequilibrium tenipernture-co~llpositioll diagram for ple cubic" phases previously reported have been the Biz0,-Si02 system, but this awaits the avail- indicated to be of substantially differeiit composiability- ol a crucible material which will not bc tion from that represented by the formula RizOa. a t.t:icked by niolteli Ri20a a t tcinlwratures abovc 7 . 'rhe solubility of BizOein Na0I.I has been S(IO0. fouiid to be proportional to the NaOH concentraThe "simple cubic form" is probably ;ti1 iriter- tion up to 2.46 N , from which the molecular incdiatc phase i r i the multi-comyollcllt system species present in the solution has beeii shown to formed by bismuth oxide a i d porcelaiii. ht NaBiOp. i1!135:l.
CAMBRIIXI;, MASSACIIUSIXTS K r i c ~ ~ SEPTEMBER v~u 17, 1942
111 the determination of the instability coristaiit of the diaiiimine silver ion Randall aiid Halford' atid Derr, Stockdale and Vosburgh2 assumed that the diamniine ion is the only complex ion formed when silver chloride and silvei iodate, respectively, are dissolved in ammonia solutions. The constants found in the two investigations agreed well and were consistelit with the assumption.
Bjerrum:' has found evidence that a monarniniiie exists. Bjerruin's method involved a fairly large uncertainty in the determination of the stability constants of the silver-ammonia ions. I t was thought desirable, therefore, to check his results for the monammine ion by a different method, and some solubility determinations have been made
( 1 3 ) I. h3. Kolthoff and 1). I
