Prof. Berzelius's Researches on Molybdcena. 135 



In order to form the protoxide of molybdaena, we may 

 make use of zinc in place of the amalgam of potassium, "but 

 the protoxide then retains the oxide of zinc in a very obstinate 

 manner. 



What is called molybdous acid, that is to say, the blue ox- 

 ide of molybdaena, is not a particular acid. It cannot be 

 combined with alkalis, which, on the contrary, decompose it, 

 by precipitating the hydrate of the yellow oxide, and combin- 

 ing with the molybdic acid. It may be produced most readi- 

 ly in dissolving the bimolybdate of ammonia, and adding to 

 it a solution of a salt with a base of the deutoxide. It pro- 

 duces a precipitate of a fine deep blue, which is very solu- 

 ble in water, and is only deposited because the water contains 

 salts. We may wash it with a solution of sal ammoniac, after- 

 wards removing the salt by a little cold water. It gives with 

 warm water a blue solution, highly saturated, which may be 

 easily preserved at the ordinary temperature of the atmo- 

 sphere. In the dry form it resembles indigo, and retains its 

 solubility in water. 



Professor Berzelius has found, that the deutoxide of molyb- 

 daena is composed of one atom of molybdaena, and two atoms 

 of oxygen. The molybdic acid contains three atoms. The blue 

 oxide is a bi-molybdate of the deutoxide of molybdaena, that is 



Mo -f 4 Mo. There is still another combination between the 

 oxide and the acid which is produced when the blue liquid is 

 digested with metallic molybdaena. It is green, equally solu- 

 ble in water, and precipitable in sal ammoniac. M. Berzelius 



supposes its composition to be Mo + 2 Mo. Tungstic acid 

 likewise combines with the deutoxide of molybdaena, and the 

 combination is very soluble in water, and of a superb pur- 

 ple colour. It is also precipitated by sal ammoniac. 



The molybdic acid performs the part of a base towards the 

 stronger acids. M. Berzelius has examined them in this point 

 of view, and has described some of the salts which it forms. 



M. Berzelius has discovered a new sulphuret of molyb- 

 daena, proportional to the molybdic acid. It is of a ruby 

 colour, transparent and crystallized. It combines with the 

 metallic protosulphurets, and forms with them particular salts, 

 of which a great number are soluble in water. 



