TUNGSTEN. 69 



either of oxide of lead or of tungstic acid. The 

 tungstate of lead that had been precipitated, 

 being collected, washed, dried, and exposed to 

 a red heat, was found to weigh 32'75 grains ; but 

 it contained just the quantity of protoxide of 

 lead in 2O75 grains of nitrate : which has been 

 shown before to amount to 14 grains. Hence, 

 it follows, that tungstate of lead is composed of 



Tungstic acid 18*75 



Protoxide oflead 1* 



32-75 



14 being the equivalent for an atom of protoxide Atom of 

 of lead, and the salt being neutral, 18-J5 mustard, 

 represent the atomic weight of tungstic acid. 



4. 29 %5 grains of crystallized tungstate of 

 soda being heated on the sand bath, gave out a 

 quantity of water, and fell into a white powder. 

 This white powder being heated to redness, 

 melted, and formed a kind of enamel, which it 

 was very difficult afterwards to separate from 

 the inside of the platinum crucible, to which it 

 had attached itself. The loss of weight amount- 

 ed to 6*75 grains. Now, 6'75 is the equivalent for 

 6 atoms of water. 



Thus, we learn that 29*5 grains of crystallized 

 tungstate of soda contain 18 '75 of tungstic acid, 

 and 6*75 of water. The remaining 4 grains 

 must be soda, and the constitution of the salt 

 may be stated as follows : 



E3 



