GICBS, — COMPLEX INORGANIC ACIDS. 277 



The same chemist has also described a very interesting series of 

 salts, which he terms molybdo-sulphites, embraced under the general 

 formula, 



4H2O . 3SO2. IOM0O3. 



Telluroso-Mulyhdates and Tungstates. 



Klein * many years since also observed the existence of complex 

 acids containing tellurous and telluric oxides and tungstic oxide. So 

 far as I am aware, no analyses have been published. A preliminary 

 notice of my own work was communicated to the Harvard Chemical 

 Club, February 12, 1884.t 



When a solution of TeBrgKo is formed with a large excess of 

 water, the salt is completely decomposed into bromhydric and tellu- 

 rous acid TeO,H,. A solution of 14: 6 acid molvbdate of ammonium 

 readily dissolves this last on boiling, and the clear filtered solution 

 soon deposits beautiful granular colorless crystals in quantity. It is 

 best to use an excess of tellurous acid. The telluroso-molybdate is 

 much less soluble than the acid molybdate of ammonium, and may be 

 redissolved and recry stall ized without apparent decomposition. When 

 a solution of the TeBr6K2 is mixed with one of the acid molybdate, • 

 a very pale yellow precipitate is formed. After standing, small bright 

 yellow crystals also appear. The white precipitate is probably only 

 tellurous acid. When freshly precipitated tellurous acid is boiled with 

 a strong solution of an acid potassic tungstate, it does not dissolve, but 

 changes character and becomes more distinctly crystalline. A solu- 

 tion of TeBrcKa gives with one of 24 : 1 : 2 phospho-tungstate of 

 sodium a very white granular precipitate, which is insoluble, and may 

 be washed with boiling, but then settles slowly. The tellurium em- 

 ployed was the best commercial product, and doubtless not absolutely 

 pure. If, as has been supposed, two different metals are embraced 

 under the name, it is possible that the compounds of the two oxides 

 with molybdic and tungstic oxides may afford means of separation in 

 consequence of differences in composition and properties. Should 

 tellurium be hereafter found to possess a technical value or interest, an 

 abundant supply can be furnished by the mines of Colorado. The 

 very high cost of the metal at present has prevented further study on 

 my part. 



* Bull, de la Societe Chimique, [2.], XLII. 169. 



t See also Berichte der deutschen chem. Gesellschaft, XVIII. 1089. August, 

 1884. 



