Discard the water layer, which contains the aspirin or acetominophen) and evaporate the chloroform layer to dryness under gentle heat. The result is codeine base, a white crystalline powder. Combine 20 mL pyridine and 25 mL conc. HCl in a beaker and heat strongly to 190C to drive off any water.
A simple sentence usually consists of a single finite clause with a finite verb that is independent. More complex sentences may contain multiple clauses. Main clauses (i.e. matrix clauses, independent clauses) are those that can stand alone as a sentence. Subordinate clauses (i.e. embedded clauses, dependent clauses) are those that would be awkward or incomplete alone.
There are two kinds of clauses: independent and dependent clauses. Most simply, an independent clause can form a complete sentence on its own and a dependent clause cannot (at least, not by itself). Think of it this way: an independent clause is like a cup of coffee, and a dependent clause is like a caffeine lover. Caffeine lovers are dependent on coffee, so the two can be joined (quite happily) to form a cohesive unit. Similarly, two cups of coffee, or two independent clauses, can be combined.