124. Two words, but and as, are used with the force of relative pronouns in some expressions; for example,—
1. There is not a leaf rotting on the highway but has force in it: how else could it rot?—Carlyle.
2. This, amongst such other troubles as most men meet with in this life, has been my heaviest affliction.—De Quincey.
Proof that they have the force of relatives.
Compare with these the two following sentences:—
3. There is nothing but is related to us, nothing that does not interest us.—Emerson.
4. There were articles of comfort and luxury such as Hester never ceased to use, but which only wealth could have purchased.—Hawthorne.
Sentence 3 shows that but is equivalent to the relative that with not, and that as after such is equivalent to which.
For as after same see "Syntax" (Sec. 417).
Former use of as.