There are two kinds, one giving the percentage of common salt in the solution, the other used by marine engineers as a guide to the point at which to blow off. Salinometers are made either of glass or brass in the form shown in the adjoining figure. On the first kind each mark represents 1 per cent, of common salt; on the second kind there are only three or four marks, one being marked " blow." To use the instrument, float the salinometer in a little of the water; the mark on the stem corresponding with the surface of the water indicates the density of the liquid.

Salinometer.