EXPERIMENTS ON MOLYBDENA. 



IdS 



boiling foV half an hour the solution was found to be much 

 stronger than in any of the preceding trials ; and on boil- 

 ing it a second time the whole of the acid and metal had 

 disappeared, except two or three grains, being converted:, 

 into blue oxide. 



I was now desirous of trying, whether I could not obtain 

 the blue oxide in a still simpler and cheaper manner, by 

 employing the brown oxide obtained from the decomposi- 

 tion of molybddte of ammonia instead of metallic molyb- 

 deoa. 



Exp. 26. A hundred grains of molybdic acid and eighty 100 grs. of acid 

 of brown oxide were triturated together, and reduced to a ^"own c!xide 

 very fine powder. This powder being wetted, after some di'^ the same, 

 time a blue colour appeared, but much more tardily than j^ "^°^ * ^'^ 

 when metallic molybdena was employed. After triturating 

 this mass however for a quarter of an hour, the magma 

 was very blue. It was then boiled four times, with four 

 ounces of water each time, and the whole was dissolved ex- 

 cept a few grains. The solutions were blue. 



Several other trials convinced me, that molybdena in 

 the metallic state acts more powerfully than the brown ox* 

 ide in converting molybdic acid into blue oxide. I found Molybdens 

 too, that by long triturating a mixture of metallic molyb- b^ownoxide 

 dena and brown oxide, and adding water from time to time, into blue by 

 so as to keep the mixture of the consistence of pap, the great- *'^'*"''^^''^" ^^ 

 er part of the mass might be converted into blue oxide. 



When the mixture was dry, I poured extremely pure Extraordinary 

 water on it, when a smell nearly resembling that of oil of ^"^^^^ ^**°* '*' 

 rosemary, faintly inclining to that of camphor, was very 

 sensibly emitted. This is a very extraordinary circumstance ; 

 but if any one should doubt the fact, I can appeal to the 

 testimony of Messrs. Trommsdorif and Haberle, who were 

 ■with me when I made the experiment. Perhaps the cause 

 of this might be discovered by operating with a lai'ger quan- 

 tity of materials. 



Exp. 27« I took all the solutions of blue oxide in pure The blue solp- 

 water produced in the preceding experiments, poured them ^"f"* evapowt- 

 into a porcelain capsule, and boiled them down to the con- 

 sistence of a sirup. As the liquor boiled it grew lighter 

 coloured, till at length it appeared of a deep steel gray ; 



Vol. :K:X— July, 1808. O and 



