Sali-nom′e-ter.
An instrument for ascertaining the saltness of water.
The
thermometrical method is by ascertaining the boiling-point of the brine.
This is used in saltworks, the scale being graduated to indicate percentages.
The
hydrometric method is by finding its specific gravity at a given temperature.
The following table shows the boiling-points and specific gravities of sea-water (at 60° Fah.) of different degrees of saturation, expressed in parts of salt contained therein, the barometer indicating 30 inches of mercury: —
| Saltness. | Boils. | Sp.
Gr. |
| Pure water | 0 | 212° | 1. |
| Common sea-water | 1 32 | 213 2° | 1.029 |
| 2 32 | 214.4° | 1 058 |
| 3 32 | 215.5° | 1.087 |
Up to this point no deposit will be formed.
| 4 32 | 216.7° | 1.116 |
| 5 32 | 217.9° | 1.145 |
| 6 32 | 219.1° | 1.174 |
| 7 32 | 220.3° | 1.203 |
| 8 32 | 221.5° | 1.232 |
| 9 32 | 222.7° | 1.261 |
| 10 32 | 223.8° | 1.290 |
| 11 32 | 225.0° | 1.319 |
| 12 32 | 226.1° | 1.348 saturated solution. |
As a general rule, the boiling-point of the water, when subjected to a pressure of one atmosphere should never be allowed to exceed 216°. The temperature must be ascertained by drawing off small quantity of the brine, and boiling it in a deep copper vessel in the engine-room, a correction being made, if necessary, for the state of the barometer.
The following table shows the hight of the boiling-point in Fahrenheit's scale at different hights of the barometer: —
| Barometer. | Boiling-point. | Barometer. | Boiling-point. |
| 27 inches. | 206.95° | 29 1/2 inches. | 211.20° |
| 27 1/2 inches. | 207.84° | 30 inches. | 212° |
| 28 inches. | 208.69° | 30 1/2 inches. | 212.79° |
| 28 1/2 inches. | 209.55° | 31 inches. | 213.57° |
| 29 inches. | 210.38° |
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Salinometer. |
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Salinometer. |
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Salinometer. |
An ordinary form of marine salinometer is a graduated glass tube, whose bottom swells into two bulbs, the lower the smaller, and containing shot, to cause the instrument to float vertically.
The greater the degree of saturation, the heavier the liquid, and the consequent hight of the graduated stem relatively to the water's surface.
The water-chamber of
Gamble's salinometer (
Fig. 4550) is connected to the boiler, so as to give a constant indication of the degree of saturation, and contains a thermometer for showing the temperature of the water in the boiler.
The case has a glass face, through which the salinometer can be seen, and the bulb has a horizontal line, whose coincidence with one of the graduations at the side of the case shows the proportion of salt contained in the water, as 1 32, 2 32, etc.; intermediate proportions may be estimated by the eye.
In
Fig. 4551, water from the boiler is drawn through the pipe
E into the cylinder
B. The upper end of the hydrometer is visible through an opening in the tube
C, so as to expose the graduations.
A thermometer
G indicates the boiling-point.
In
Fig. 4552, an inner tube is weighted to balance a column of water of known hight and density, and rests upon a flexible diaphragm, through which the pressure of the water is transmitted.
Variations of pressure are indicated by an index connected with the upper end of the tube and traversing the dial.
