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.
A primary division for the discussion of clauses is the distinction between main clauses (i.e. matrix clauses, independent clauses) and subordinate clauses (i.e. embedded clauses, dependent clauses). A main clause can stand alone, i.e. it can constitute a complete sentence by itself. A subordinate clause (i.e. embedded clause), in contrast, is reliant on the appearance of a main clause; it depends on the main clause and is therefore a dependent clause, whereas the main clause is an independent clause.