To test this, notice the following:—
In (1), to look means that he might look; to please is equivalent to that he may please,—both purpose clauses.
In (2), to find shows the result of the return; not to take pity is equivalent to that it would not take pity.
In (3), to part means because I part, etc.; and to betray and to bring express the reason, equivalent to that you betray, etc.
In (4), to serve and to talk are equivalent to [as much gold] as will serve us; and "too sad to talk" also shows degree.
In (5), to hear means if you should hear, and to say is equivalent to if we say,—both expressing condition.
363. V. The independent use, which is of two kinds,—
(1) Thrown loosely into the sentence; as in Sec. 355, (3).
(2) Exclamatory: "I a philosopher! I advance pretensions;" "'He to die!' resumed the bishop." (See also Sec. 268, 4.)