Trial No.

Reagent used

Reagent volume (ml)

Temperature

(˚C)

Digestion

time (h)

Observation

1

HNO₃:HClO₄

5:1

150

1:30

Light yellow

2

HNO₃:HClO₄

4:2

180

1:50

Deep yellow

3

HNO₃:HClO₄

3:3

180

2:10

Clear yellow

4

HNO₃:HClO₄

4:1

210

2:30

Pale yellow

5

HNO₃:HClO₄*

3:2*

240*

2:50*

Clear colorless

6

HNO₃:HClO₄

4:2

270

3:10

Almost clear