Calculation- Calculate LOI as follows: LOI, (A-B CX100 where: A mass of crucible sample, g, B mass of crucible plus sample after ignition, g, and C mass of sample, g 19.5 Precision and Bias: 19.5.1 Fifteen laboratories cooperated in testing on three samples of high calcium limestone to obtain the precision data for percent LOI given in 19.5.2 and 19.5.3. 19.5.2 The repeatability (Practice E 691 r) was found to be 0.158 LOI. 19.5.3 The reproducibility (Practice E 691 [R) was found to be 0.463 LOI. The user is cautioned to verify by the use of reference materials, if available, that the bias of this test method is adequate for the contemplated use.