Drying or lenition
There are now two standard temperatures used for drying residues or solids; one is 103 and the other is 180. A temperature of 103 to 105 was the only temperature stipulated in the past because many of the residues or solids involved in environmental engineering practice are organic in nature and release water of composition in significant amounts at higher temperatures. Drying at 103 ensures the removal of all free water, provided that the drying period is long enough, and minimizes the loss of water of crystallization. However, sometimes it is desirable with water supplies not containing significant concentrations of organic material to have summation of individually determined mineral species. For this purpose a drying temperature of 180 may be specified. Obviously, the drying temperature should be specified when reporting results because of the differences that can be obtained.