18.
Take exactly equal quantities of lard and butter; mix a small piece of the butter intimately with all the lard. From this blend take a piece just as large as the fragment removed from the butter, and mix this thoroughly with the butter. Is there now more lard in the butter or more butter in the lard?
WHERE IS THE FALLACY?
19. Here is an apparent proof that 2 = 3:—
4 - 10 = 9 - 15
4 - 10 + 25⁄4 = 9 - 15 + 25⁄4
and the square roots of these:—
2 - 5⁄2 = 3 - 5⁄2