Nisil is an alloy of nickel (95.5% wt.) and silicon (4.4% wt.) with traces of Mg (0.1% wt.), which is non-magnetic.
Nisil melts at 1341 - 1420 ðC, has a density of 8.58 g/cm<sup>3</sup>, and electrical resistivity of 0.365 éâ mm<sup>2</sup>/m at 20 ðC.
It is often used in conjunction with Nicrosil in type N thermocouples. In this use, it serves as the negative leg of the thermocouple. It offers higher thermoelectric stability in air above 1000ðC (1830ðF) and better oxidation resistance than type E, J and K thermocouples. It can not be exposed to sulphur-containing gases.