Any of the editions of the *Chemical Rubber Company
Handbook of Chemistry and Physics*; there are other CRC
handbooks, such as the *CRC Standard Mathematical Tables and
Formulae*, but “the” CRC handbook is the chemistry
and physics reference. It is massive tome full of mathematical tables,
physical constants of thousands of alloys and chemical compounds,
dielectric strengths, vapor pressure, resistivity, and the like. Hackers
have remarkably little actual use for these sorts of arcana, but are such
information junkies that a large percentage of them acquire copies anyway
and would feel vaguely bereft if they couldn't look up the magnetic
susceptibility of potassium permanganate at a moment's notice. On hackers'
bookshelves, the CRC handbook is rather likely to keep company with an
unabridged Oxford English Dictionary and a good atlas.