A form of the calorie formerly used in chemistry. The thermochemical calorie was defined in 1935 to equal exactly 4.184 joules. This is slightly smaller than the International Steam Table calorie (4.1868 joules) defined in 1956
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}