CHEMICAL ANALYSIS 



15 



at rest , before any further manipulations are tried. There- 

 after more of the substance is added, and the same tech- 

 nique carefully observed. 



To obtain the weight of a substance or dish, or both, these 

 are placed in the left-hand pan, and a trial weight is put 

 on the right pan. If this is too much, the next lower 

 weight is tried, and so on, being careful to observe the 

 technique outlined above. The weight is read from the 

 vacant spaces in the case, and checked on removing the 

 weights. Always use a watch-glass in weighing a salt or 

 substance not contained in a vessel of some kind. 



Atomic Weights 



of the elements the 

 recently assigned. 



Aluminium 



Arsenic 



Barium 



Boron 



Bromine 



Calcium 



Carbon 



Chlorine 



Copper 



Hydrogen . . 



Iodine 



Iron 



Lead 



Magnesium . 



Manganese. . 



Mercury 



Nitrogen . . 



Oxygen 



Phosphorus 



Potassium 



Silver 



Sodium 



Sulphur 



Tin 



Zinc 



The following table gives for some 

 older atomic weight, and that more 



