630 abstracts: analytical chemistry 



Experiments were made on the tridymite-cristobalite inversion tem- 

 perature, which was found for this system to be below i500°C., in ap- 

 proximate agreement with Fenner's original value of 1470°. 



J. B. F. 



INORGANIC CHEMISTRY.— Wollastonite {CaOSiO^) and related 

 solid solutions in the ternary system lime^nagnesia-silica. J. B. 

 Ferguson and H. B. Merwin. Amer. Journ. vSci. 48: 165-189. 

 September, 19 19. 



The study of the ternary system CaO-MgO-SiOo brought to light 

 many perplexing liquidus relations for which there was no adequate ex- 

 planation. An investigation of the solidus relations was therefore 

 started in order to clear up the doubtful points, and the results of this 

 investigation are given in this paper. The salient features of these 

 results are: (i) A confirmation of the earlier work in regard to the 

 wollastoni-te-diopside solid solutions, wollastonite taking up a maximum 

 of 17 per cent of diopside. (2) The existence of solid solutions of pseudo- 

 wollastonite and diopside containing as a maximum about 16 percent 

 of diopside. (3) The finding of the new compound, 5Ca0.2Mg0.6Si02. 

 (4) The existence of solid solutions of akermanite (or perhaps of an 

 unstable compound, 3CaO.Mg0.3Si02) in wollastonite and pseudo- 

 wollastonite. The wollastonite solutions extend to a composition con- 

 taining between 60 and 70 per cent of akermanite, while the pseudo- 

 wollastonite solutions extend to a composition containing about 23 per 

 cent of the same compound. (5) The presence of an area of solid solu- 

 tion which includes the wollastonite-diopside, the wollastonite-aker- 

 manite, and the wollastonite-5Ca0.2Mg0.6Si02 solid solutions. 



In addition to the results just mentioned, which suffice to clear up the 

 liquidus relations in question, as thorough an investigation as the nature 

 of the problem and the available methods of attack would permit was 

 carried out upon the solid solutions of silica and 3Ca0.2Si02 in calcium 

 metasilicate and upon the inversion and decomposition temperatures 

 of all the various solid solutions. A general discussion of these results 

 with diagram and models, is given. J. B. F. 



ANALYTICAL CYLUMISTRY .—Electrometric titrations, with special 



reference to the determination of ferrous and ferric iron. J. C. Hos- 



tetter and H. S. Roberts. Journ. Amer. Chem. Soc. 41: 1337- 



1357. September, 1919. 



The advantages of the electrometric method for titrating, oxidizing, 



and reducing reactions may be summarized as follows: (i) This 



