(I) Carius method

• Procedure: A known mass of the organic compound is taken in a clean carius tube and few mL of fuming HNO₃ is added and then the tube is sealed. It is then placed in an iron tube and heated for 5 hours. The tube is allowed to cool and a hole is made to allow gases to escape. 
• The carius tube is broken and the content collected in a beaker. Excess of BaCl₂ is added to the beaker. H₂SO₄ formed is converted to BaSO₄ (white ppt.) The precipitate is filtered, washed, dried and weight. From the mass of BaSO₄ , percentage of S is calculated.

(II) Calculation: 

Mass of organic compound = Wg 

233 g of BaSO₄ contains 32 g of sulphur 

Percentage of sulphur =\((\frac{32}{233} \times \frac{x}{ω} \times 100)\)%

(II) Distillation is used in case of volatile liquid mixed with a non-volatile impurities. 

Distillation under reduced pressure: 

This method is used to purify such liquids which have very high boiling points and which decompose at or below their boiling points. Steam distillation is used to purify steam volatile liquids associated with water immiscible impurities.