Hortvet vs. Celsius in Cryoscope

Hi, Dairy Scientists How to convert degrees Celsius to Hortvet and vice versa? Temp. reading in Celsius = 0.9656 x Temp. reading in Hortvet. Temp. reading in Hortvet = 1.0356 x Temp. reading in Celsius. Thus -0.512 Celsius = -0.530 Hortvet Regards, Leon the Milkman Â