Published online by Cambridge University Press: 26 July 2017
The technique of freeing fossils from carbonate rocks by the use of various acids has been known for many years, but still is not used as widely as might be expected. Cooper and Whittington (1965) cited early uses of acid to prepare graptolites and eurypterids (Holm, 1890; 1898). Common practice among early paleontological users of acid was to pick up a silicified specimen, or carefully chip one out of the matrix by hammer and chisel, and use the acid to clean it or to expose internal features. For example, Waagen (1882, p.354) mentioned exposing the internal features of silicified brachiopods by use of “dilute acid” (kind unspecified) from Permian rocks in the Salt Range of India (now Pakistan).