Brix scale
Refractometers are widely used to measure the amount of dissolved substances in solutions containing mainly sucrose. The relationship between refractive index and the amount of dry substance content is well known for sucrose and is the basis of the Brix scale which is measure of the number of grams of sucrose present per 100 grams of aqueous sugar solution. (50 Brix means 50 grams of solid per 100 gms of solution) This relationship holds for a large number of similar substances and so the Brix scale is widely used in the food industry. Unfortunately the refractive index of a sugar solution changes with temperature while its solid content remains the same. ( The same refractive index at different temperatures correspond to different Brix values.) Manual "Abbe" refractometers do not compensate for this temperature effect and manual correction tables should be used to adjust the readings to a standard temperature.