A salinometer was an instrument designed to calculate the salinity content.
Below is the instruction of how to use it:
1, Handle the salinometer with care.
2, Draw off a sample of liquid to be tested into the trial jar.
3, Gently lower the hydrometer into the liquid until it floats freely.
4, Spin the hydrometer to eliminate any air bubbles clinging to the side as if this is not done a false reading may be obtained.
5, When the hydrometer stops moving and is not in contact with the side or bottom of the trial jar, take reading as shown on the below sign. The number you read is the density of the liquid.