The hydrometer intended for densities less than that of water, or the hydrometer for spirits, is constructed on a similar principle. The instrument is so arranged that it floats in pure water with most of the stem above the surface. A solution containing 10% of pure salt is used to indicate the zero of the scale, and the point at which the instrument floats when immersed in distilled water at 10° R. (54½° F.) is numbered 10. Equal divisions are then marked off upwards along the stem as far as the 50th degree. The densities corresponding to the several degrees of Baumé's hydrometer are given by Nicholson (_Journal of Philosophy_, i. 89) as follows:-- _Baumé's Hydrometer for Spirits. Temperature 10° R._ +--------+--------+--------+--------+--------+--------+ |Degrees.|Density.|Degrees.|Density.|Degrees.|Density.| +--------+--------+--------+--------+--------+--------+ | 10 | 1.000 | 21 | .922 | 31 | .861 | | 11 | .990 | 22 | .915 | 32 | .856 | | 12 | .985 | 23 | .909 | 33 | .852 | | 13 | .977 | 24 | .903 | 34 | .847 | | 14 | .970 | 25 | .897 | 35 | .842 | | 15 | .963 | 26 | .892 | 36 | .837 | | 16 | .955 | 27 | .886 | 37 | .832 | | 17 | .949 | 28 | .880 | 38 | .827 | | 18 | .943 | 29 | .874 | 39 | .822 | | 19 | .935 | 30 | .867 | 40 | .817 | | 20 | .928 | | | | | +--------+--------+--------+--------+--------+--------+ _Baume's Hydrometer for Salts._ +--------+--------+--------+--------+--------+--------+ |Degrees.|Density.|Degrees.|Density.|Degrees.|Density.| +--------+--------+--------+--------+--------+--------+ | 0 | 1.000 | 27 | 1.230 | 51 | 1.547 | | 3 | 1.020 | 30 | 1.261 | 54 | 1.594 | | 6 | 1.040 | 33 | 1.295 | 57 | 1.659 | | 9 | 1.064 | 36 | 1.333 | 60 | 1.717 | | 12 | 1.089 | 39 | 1.373 | 63 | 1.779 | | 15 | 1.114 | 42 | 1.414 | 66 | 1.848 | | 18 | 1.140 | 45 | 1.455 | 69 | 1.920 | | 21 | 1.170 | 48 | 1.500 | 72 | 2.000 | | 24 | 1.200 | | | | | +--------+--------+--------+--------+--------+--------+ Carrier's hydrometer was very similar to that of Baumé, Cartier having been employed by the latter to construct his instruments for the French revenue. The point at which the instrument floated in distilled water was marked 10° by Cartier, and 30° on Carrier's scale corresponded to 32° on Baumé's.