Nujol is a brand of mineral oil by Plough Inc., cas number 8042-47-5, and density 0.838 g/mL at 25 °C, used in infrared spectroscopy. It is a heavy paraffin oil so it's chemically inert and has a relatively uncomplicated IR spectrum, with major peaks between 2950-2800, 1465-1450, and 1380-1370 cm-1. The empirical formula of Nujol is hard to determine exactly because it's a mixture but it's essentially the alkane formula where n is very large. To obtain an IR spectrum of a solid, a sample is… (More on Nujol)