Abundance of the chemical elements in the Sun and outer planets is similar to that in the universe. Due to solar heating, the elements of Earth and the inner rocky planets of the Solar System have undergone an additional depletion of volatile hydrogen, helium, neon, nitrogen, and carbon (which volatilizes as methane). The crust, mantle, and core of the Earth show evidence of chemical segregation plus some sequestration by density. Lighter silicates of aluminum are found in the crust, with more magnesium silicate in the mantle, while metallic iron and nickel compose the core. The abundance of elements in specialized environments, such as atmospheres, or
The Elements of Programming Style edition). Its lessons are summarized at the end of each section in pithy maxims, such as "Let the machine do the dirty work": Modern readers may find it a shortcoming that its examples use older procedural programming languages (Fortran and PL/I) which are quite different from those popular today. Few of today's popular languages had been invented when this book was written. However, many of the book's points that generally concern stylistic and structural issues transcend the details of particular languages. "Kilobaud Microcomputing" stated that "If you intend to write programs to be used by other people, then you should