# Density Method

Density of crystalline region remains always greater than amorphous region,A density gradient column is normally made in a glass tube between 750mm and 1500 mm long and 35 to 60mm diameter .It is mounted vertically in a water bath and held at a constant temperature.The column is filled with partially miscible liquid in proportion varying gradually up the column.In this way column shows gradual variation of density from bottom top in decreasing order.requirement for the density gradient column

1. Required two types of chemicals (E& D)of different density.
2. The chemicals should not reactable with each other.
3. They should partially miscible with each other.
4. Four balls
5. Sliding telescope
6. Meter scale

The specific volume of the material (volume per unit mass) is the sum of volume of crystalline and volume of amorphous region ,hence the specific volume of any crystalline material can be expressed by the rule of additivity-

V = XVc+(1-X)Va

Where X is the mass fraction of the crystalline phase and Vc and Va are the specific volume of the crystalline and amorphous phase.
m=1  ,              V=1/e
specific volume is the volume of the unit mass.
1/e=X(1/ec+1/ea)
After calculation,
X=ec/e*(e-ec)/(ec-ea)