90-0 



90-0 



1-49 



1-5 





(8-5) 



1 12 MLrt, i- — Heat of Formation of the 



out. An intimate mixture of 23 grams of vanadium pentoxide 

 and 19 grams of magnesium powder was heated in a heavy 

 brass bomh. At a temperature below redness the reaction 

 occurred and the bomb became red hot. The porous brown 

 product was digested with a solution of ammonium chloride 

 which dissolved the metallic magnesium present but not 

 the vanadate or vanadite. The product was next washed, 

 dried, pulverized and then repeatedly digested with very dilute 

 hydrochloric acid and finally with acid diluted with two 

 volumes of water. The product at this stage consisted of 

 grains having a metallic luster and a brown powder. The 

 latter was floated off and the residue was washed and then 

 dried in a partial vacuum over sulphuric acid. It was a mix- 

 ture of bright metallic-like particles and a grey powder. It 

 was slowly acted on by hot concentrated hydrochloric acid 

 with evolution of gas, but was not completely dissolved. It 

 was marked "A" and analyzed with the following results : 



I II Mean. 



Vanadium ; 90' 1 



Magnesium oxide .. 1*44 



Oxygen by difference 



The atomic ratio of the vanadium to the oxygen is 3 - 3 to 1. 



Next a mixture of 38 grams of vanadium trioxide and 22 

 grams of magnesium was heated in a steel bomb and kept at a 

 cherry red heat for some time. Then the bomb was cooled 

 under water to prevent oxidation of its contents. The pro- 

 duct was digested with hot concentrated hydrochloric acid, 

 washed once and then left for a day in dilute acid. It was 

 finally washed and dried as usual. The product was 18 grams 

 and it was found to contain 85 - 2 per cent of vanadium. It 

 was treated again with hot concentrated hydrochloric acid and 

 considerable hydrogen was' evolved. The residue was finally 

 washed with alcohol and dried in a partial vacuum. It 

 weighed 12 grams and was marked "B". An analysis gave 

 84*5 per cent of vanadium and 0*2 per cent of magnesium 

 oxide. After standing two weeks the vanadium was found to 

 be 83'1. Vanadium monoxide, V 2 0, contains 86 - 4 per cent of 

 the metal. 



Another preparation, marked " C," was made in the same 

 way as the 18 grams above described, and contained 89 - 7 per 

 cent of vanadium. It was a dark gray powder showing no 

 metallic particles under a magnifying glass. The metal 

 reduced by magnesium is in an exceedingly fine powder which 

 settles slowly in water and in the best condition to oxidize. 

 The oxidized product, however, appears to be a mixture, for it 



