Bodies sink in fluids, in a _compound ratio_ to the volume and the density of those fluids, which they displace. It is from that law of nature, that a ship sinks 20 feet in fresh water, while it sinks only about 18 feet in sea water, which has more density on account of the salt dissolved therein. The reverse of this effect takes place in fluids lighter than water, as bodies floating in them sink the more, as the liquor has less density. Upon those principles are made two kinds of areometers--one for fluids denser than water; the other for those that are lighter: the first are called _salt proof_; the second _spirit proof_. Distilled water is the basis of those two scales: it is at the top for the _salt proof_, and at the bottom for the _spirit proof_; because the first is ascending, and the other descending; but by a useless singularity, the distilled water has been graduated at 10 deg. for the spirit proof bottle, and at 0 for the _salt proof_. We shall only dwell upon the first, because it is the only one interesting to the distiller. Water being graduated at 10 deg. in the areometer, it results from thence that the spirit going to 20 deg., is in reality only 10 deg. lighter than water; and the alcohol gaaduated [TR: graduated] at 35 deg., is only 25 deg. above distilled water. The areometer can only be just, when the atmosphere is temperate; that is, at 55 deg. Fahrenheit, or 10 deg. Reaumur. The variations in cold or heat influence liquors; they acquire density in the cold, and lose it in the heat: hence follows that the areometer does not sink enough in the winter, and sinks too much in the summer. Naturalists have observed that variation, and regulated it. They have ascertained that 1 deg. of heat above temperate, according to the scale of Reaumur, sinks the areometer 1/8 of a degree more; and that 1 deg. less of heat, had the contrary effect: thus the heat being at 18 deg. of Reaumur, the spirit marking 21 deg. by the areometer, is really only at 20 deg.. The cold being at 8 deg. below temperate, the spirit marking only 19 deg. by the areometer, is in reality at 20 deg.. 2-1/4 of Fahrenheit corresponding to 1 deg. of Reaumur, occasion in like manner a variation of 1/8 of a degree: thus, the heat being at 78-1/2 deg., the spirit thus marking 21 deg., is only at 20; and the cold being at 87 deg., the spirit marking only 19 deg. by the areometer, is in reality at 20 deg..