On a Piece of Chalk was a lecture given by Thomas Henry Huxley on 26 August 1868[1] to the working men of Norwich during a meeting of the British Association for the Advancement of Science.

[2] It was published as an essay in Macmillan's Magazine in London later that year.

[3] On a Piece of Chalk was republished by Scribner in 1967 with an introduction by Loren Eiseley and illustrations by Rudolf Freund.

[2] In 1967, Dael Wolfle of the AAAS gave a favorable review for On a Piece of Chalk, writing: That the lessons of paleontology are now so much more widely appreciated than they were when Huxley drew them from a piece of carpenter's chalk is in good measure a tribute to Huxley's genius.

[2]In April 2015, physicist and Nobel laureate Steven Weinberg included On a Piece of Chalk in a personal list of "the 13 best science books for the general reader".