4 Preparation of Substances 



treated similarly it will be seen that only an 

 inappreciable amount of phosphate dissolvs 

 in water. 



Test for Lime. — Dissolv some of the 

 superphosphate in water and filter as before. 

 To the clear filtrate add a solution of oxalic 

 acid or ammonium oxalate. The white 

 precipitate that forms is calcium oxalate 

 which shows the presence of calcium com- 

 pounds in solution. 



NOTES 



The Beaum^ hydrometer is an instrument 

 for determining density that has wide indus- 

 trial use. It is, however, unscientific as it has 



Sulfuric Acid. 



Specific Gravity of Aqueous Solu- 

 tions 



two separate scales, one for liquids heavier 

 than water and rre for liquids lighter than 

 water, the two having no relation. Further, 



