144 



Mixter — Heat of Formation of the 



interstices are invisible. The preparation designated as "D" 

 was fairly pure as shown by the following : 10-413 grams lost 

 on heating to faint redness in hydrogen 1*8300 gram or 17'61 

 per cent, the calculated loss being 17*58 per cent when V 2 6 is 

 changed to V,0 3 . The vanadium trioxide obtained in the 

 experiment is designated as " F ". A portion of " D " was 

 fused in a platinum dish and the red crystalline sample 

 obtained was marked " E ". 



The calorimetric experiments 3 and 1 were made with the 

 yellowish-brown so-called amorphous sample " D ", and 5 and 

 6 with red crystalline portion " E ". The following are the 

 data and results : 



3 4 5 6 



Vanadate pentoxide .. 5-201 5-062 5-T73 5-090 grs. 



Sulphur 1-000 1-000 1-000 1-000 " 



Sodium peroxide 16- 16* 16- 16- " 



Water equivalent of system 3075 3118 3087 3118 " 



Temperature interval 3-190° 3-104° 3-185° 3-116° 



Heateffect 9809° 9678° 9832 c 9716° 



" " ofsulphur —5270 —5270 —5290 —5270 



" " of oxygen evolved +176 +176 +175 +177 



4715 4584 4737 4623 

 « « of 1 gram of V 3 6 907° 906° 911° 908 c 



It was found in Exp. 4 that the connections for collecting 

 the oxygen evolved leaked, hence the same correction is made 

 in 3 and 4 as for 4 and 5, as the conditions were essentially 

 alike in all of the experiments. It appears from the results 

 that the so-called amorphous form of vanadium pentoxide is 

 crystalline, for if it is amorphous the heat effect should be 

 higher than that of the red crystalline form. The average of 

 the last two experiments is 910°. For 1 gram molecule of 

 vanadium pentoxide combining with sodium oxide it is 

 165,000°. 



Vanadium Trioxide. 



Vanadium trioxide, preparation " F ", was used in the fol- 

 lowing experiments : 



7 8 



Vanadium trioxide 3-121 . 3-325 grams. 



Sulphur '.._ 1-000 1-000 " 



Sodium peroxide 16* 19- " 



Water equivalent of system 3056 3134 " 



Temperature interval 3-225° 3-197° 



Heateffect 9856° 10019° 



" " ofsulphur —5270 —5270 



" " " oxygen absorbed . . — 51 — 59 



4535 4690 



" " " 1 gram of V a O s .. 1453° 1411° 



