1894.] Oob [Pennington and Smith. 



which these oxidations were performed. All draughts were avoided. 

 The crucibles were handled with nickel crucible tongs. They were al- 

 lowed to cool in vacuum desiccators over sulphuric acid. Calcium chlo- 

 ride cannot apparently be used for this purpose, at least a superficial 

 greenish tinge was always noticed on the oxide cooled in this way. Di- 

 rect sunlight also causes a reduction of the trioxide, therefore the desicca- 

 tors were kept covered with a black cloth. 



At the beginning of each oxidation the flame applied was quite small. 

 The metal increased in bulk as it oxidized, and in five minutes had assumed 

 a light yellowishgreeu color. At the expiration of half an hour the heat 

 was increased. Later a stronger heat was allovv'ed to act and continued 

 until the oxidation was finished. The first period of each oxidation con- 

 tinued through five hours. The crucible and contents were cooled and 

 weighed. The second period lasted three hours additional, after whicli 

 tlie crucible was allowed to cool. It was again weighed, and even if there 

 was no change in weiglit from that first recorded, the ignition was con- 

 tinued for two hours more. The third weight, if constant, was taken as 

 final. Each oxidation, therefore, was not considered finished until it had 

 been continued through a period of at least ten hours. 



The weighings were made upon a Becker balance with weights, which 

 had been adjusted for this work. The vacuum standard was observed, 

 and oxygen taken equal to sixteen in all the calculations. The results 

 were as follows : 



WEIGHT OP WEIGHT OF ATOMIC 



TUNGSTEN OXYGEN MASS 



IN IN OP 



GRAMS. GRAMS. W. 



1.— 0.86-2871— 0.323952— 184.942 

 2._0.650700— 0.168900— 184.933 

 3._0..597654— 0.155143— 184.909 

 4._0.666830— 0.173103— 184.903 

 5 . _0. 428338— 0. 1 111 68— 1 84. 900 

 6. —0. 67 1 930— 0. 1 74406— 1 84.925 

 7._0.590230— 0.153193— 184.933 

 8.— 0.568654— 0.147588— 184 943 

 9._1.080973—0.380600— 184.913 



Mean 1 84.921 



Maximum 184.943 



Minimum 184.900 



.043 



Clarke (Recalculation of the Atomic Weights, 1882, "Washington) and 

 Becker {Atomic Weight Determinations, 1880, Washington) in their recal- 

 culations of this constant of tungsten both arrive at the figures 184.02 



