[ortusdux]

Testing for melting point depression is a common diagnostic method used in chemistry to check for impurities. Pure compounds melt at known temperatures, and typically do so within a narrow range (+/- 0.5 °C). Impurities almost always lower the melting point and widen this band. I spent a lot of my undergrad chem courses packing my products into capillary sized test-tubes and watching them slowly melt.

https://www.mt.com/us/en/home/applications/Application_Brows...

Some companies leverage this effect to make non-reversible temperature indicators that change color at specific temperatures.

https://www.mcmaster.com/temperature-indicating-stickers/

[rootw0rm]

that's funny, i literally just grabbed a melting point apparatus out of storage to get rid of, because I have too much stuff laying around I probably won't use again

[vondur]

Boy did I hate staring at a mel-temp apparatus...