In thermodynamics, a positive transformation, as contrasted with a negative transformation, is the transformation that results from the conversion of work into heat and therefore the passage of heat from a higher to a lower temperature. 
Clausius footnotes this 1854 version of the positive transformation definition with the comment “the reason why this choice of positive and negative senses is preferable to the opposite one, will become apparent after the theorems relative to the transformations have been enunciated (1864). The exact details of this 1864 asterisk remain to be tracked down, but seem to refer the 1864 "Appendix to the Fifth Memoir: On Some Approximate Formula employed to Facilitate Calculations. 
● Positive work
● Negative work
● Double transformation
● Uncompensated transformation
● Transformation content
● Equivalence-value of all uncompensated transformations
1. Clausius, Rudolf. (1865). The Mechanical Theory of Heat (positive transformations, pg. 123). John van Voorst.
2. Clausius, Rudolf. (1865). The Mechanical Theory of Heat (pgs. 208-14). John van Voorst.