The present invention relates to a novel device that enables a person to gauge the brine density in solar salt works from afar without recourse to sampling of the brine. The devicenullwhich can be considered as an improvisation over the conventional laboratory type Baume meternullcan be placed directly in the salt pan. The device remains sunk, and therefore invisible, until the desired density of brine is approached. Thereafter it gradually floats up and becomes visible from afar. From appropriate markings on the rod connected to the top end of the device, it can be gauged whether the brine is yet to attain the desired density, or has attained the desired density range, or has exceeded the desired density range. The device is resistant to corrosion and able to combat extreme weather conditions prevailing in solar salt works. The control of brine density from afar helps eliminate the need for frequent sampling of brine for density measurement that would make adherence to the optimum process of salt production easier. The methodology can be extended to production of other marine chemicals such as carnallite and kainite.