Previously utilized as a secondary fixed point, the melting point of Gallium has been assigned a temperature of 302.9146 K (29.7646 °C) and adopted as a defining fixed point on the International Temperature Scale of 1990 (ITS-90). And Pond Engineering has designed a user-friendly, high-performance system to realize it.
Following the geometry presented in NIST Technical Note 1265, our model K28C Gallium Melting Point cells contain approximately 1 kg of .999 999 9 pure Gallium sealed in an inert plastic crucible and surrounded by a durable welded stainless steel envelope. This construction easily accommodates the approximate 3% expansion of the freezing Gallium, while maintaining the required 1 standard atmosphere pressure of high purity Argon gas surrounding the metal sample. Welded Type 304 Stainless Steel removes the risk of cell breakage in normal use and the high purity metal sample produces a remarkably stable, long-lasting temperature plateau. Typical melt plateau variations are less than .0002°C over 24 hours.