IX.
Before going on to a discussion of the conditions of uric-acid formation, uric-acid decomposition and uric-acid elimination in pathologic states it is necessary, in order that the discussion may be intelligible, to review briefly the facts which have been established regarding the chemical nature and physical properties of uric acid and the urates. The empirical formula for uric acid has long been known as C5H4N4O3. As a rational formula, Medicus suggested the structure
and this has been proved by Emil Fischer1 to be correct. The latter investigator was the one to show that uric acid is only one of a large series of allied substances known as the purin bodies, since they are all derivatives of a substance, which Fischer discovered and made synthetically, known as purin C5H4N4. All these purin bodies contain the group C5N4, the atoms in this group (the so-called "purin nucleus") being arranged thus:
Each