Pennington and Smith.] do^ | Nov 2, 



12 And moreover by tbem my son, be warned: 

 Of making many books tbere is no end : 

 And much anxious thought 



Is a weariness of the fliesh. 



The end of the discourse, the whole, listen to : 



13 Fear God : 



And keep His commandments : 

 For that is the whole (of) man. 



14 For God will bring every deed into judgment : 

 With every hidden thing, 



Whether it be good 

 Or whether it be evil. 



l^ie Atomic Mass of Tungsten. 



By Mary E. Pennington and Edgar F. Smith. 



{Read before the American Philosophical Society, November 2, 1S94.. ) 



A study of the literature relating to this subject discloses the fact that 

 while, in most instances, every effort was made to eliminate foreign mat- 

 ter from the material employed in the numerous investigations which 

 have been conducted at various times, several doubtful points continue. 

 The object of this communication is to direct attention to one of these pos- 

 sible sources of error, viz., the presence of traces of molybdenum, and 

 to present results obtained after its evident removal. 



The earlier investigations relating to the atomic mass of tungsten are 

 rather numerous ; bitt of these that of Schneider is without doubt de- 

 serving of the most confidence, chiefly for the pains taken in preparing 

 pure material for the later experiments. The author offers sati?factory 

 evidence of the absence of possible contaminating substances, and in writ- 

 ing of the presence of molybdenum employs these words : " Molybdan 

 endlich nicht, well die Molybdansiiure in heftiger Gliihhitze fliichtig ist " 

 {Journ. prakt. Chemie, 50, p. 158). The experience of chemists generally 

 is that a complete separation of tungsten trioxide from molybdenum triox- 

 ide cannot be attained in this way. Indeed, an examination of the exper- 

 iments recorded by Schneider discloses the fact that he, while engaged in 

 reducing strongly ignited tungsten trioxide, several times discovered on 

 the anterior portion of the reduction or combustion tube " ein weiss- 

 liches Sublimat." This sublimate Schneider attributes to tungsten chlo- 

 ride, but the question may well be asked, Was it not molybdic acid? 



Waddell has made the most recent contribution to our knowledge upon 

 the atomic mass of tungsten {Amer. CJiem. Journ., S, 280). He experi- 



