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 VIII. Intelligence and Miscellaneous Articles. 



CHEMICAL ANALYSIS OF TWO MINERAL PRODUCTS FORMED BY 

 SUBLIMATION IN THE ERUPTION OF VESUVIUS IN 1858. BY 

 M. CAPPA. 



HPHESE two products, which by their physical properties appear to 

 ■*■ be cotannite, are of a yellow colour and not lustrous. The two 

 specimens were marked A and B, and the results obtained were : — 



A . Chlorine ; sulphuric, and traces of silicic acids ; lead in large 

 quantity ; copper, and a small quantity of sodium. 



B. Chlorine, copper, and lead. 



A, from its physical and chemical properties, might be considered 

 as oxychloride of lead mixed with small quantities of chlorides of 

 copper and sodium, along with traces of sulphates and silicates. The 

 compounds PbO, Pb CI, and '2 PbO, PbCl are well known. A seems 

 to belong to the former species, — a supposition which appears more 

 probable when it is remembered that oxychloride of lead is commer- 

 cially obtained by treating oxide of lead with chloride of sodium and 

 water. The hydrated body thus obtained becomes yellow by calci- 

 nation. Probably the lead placed under the same circumstances in 

 the presence of chloride of sodium and aqueous vapour, has given 

 rise to the above compound. 



B appears to be oxychloride of lead with a small quantity of chlo- 

 ride of copper. — Comptes Rendus, May 21, 1860. 



ON THE FLUOZIRCONATES, AND ON THE FORMULA OF ZIRCONIA. 

 BY C. MARIGNAC. 



The formula for zirconia generally adopted, Zr a 3 , was proposed 

 by Berzelius, who was led to it by a comparison of the composition 

 of two compounds which fluoride of zirconium forms with fluoride 

 of potassium. The formula ZrO, assumed by some chemists, is quite 

 indefensible. Neither it nor the formula Zr Q s are in harmony 

 with the properties of the body. 



Recently Deville and Troost's researches* on the vapour-density 

 of chloride of zirconium have led to the formula Zr CI" 2 . Zirconia, 

 on this hypothesis, would be a binoxide allied to titanic, stannic, 

 and silicic acids. The similarity of zirconium to silicium was pointed 

 out by Berzelius, and he was only prevented from placing them 

 together by the necessity of classifying the elements into metals and 

 metalloids. The resemblance, too, of titanic acid and zirconia is so 

 great, that it is almost impossible to separate them by analysis. 



Marignac has undertaken a comparative study of the fluozirconates 

 with a view of throwing light on the question. The material for 

 the research was obtained by treating zirconia with hydrofluorate of 

 fluoride of potassium at a red heat. A mixture of fluosilicate and 

 fluozirconate of potash is obtained, from which the latter salt is 

 readily obtained pure. 



Fluoride of zirconium forms double salts with a great number of 

 t Phil. Mag. vol. xv. p. 459. 



