178 GRAVITY (SPECIFIC) GRAY provided with a stopcock. The vessel is ex- hausted of air before the introduction of the gas. The experiment requires particular care, as the result will be found to vary under differ- ent conditions of pressure, temperature, and the hygrometric state of the atmosphere. The temperature of the air should be 60 and baro- metric pressure 30 inches. The specific gravi- ties may also be calculated from the atomic weights of the gases : when the atomic volume is equal to that of hydrogen, it is obtained by multiplying the specific gravity of hydrogen by the atomic weight of the gas ; when the atomic volume is half that of hydrogen, the specific gravity of the gas is equal to the specific gravi- ty of hydrogen multiplied by twice the atomic weight of the gas ; and when the atomic vol- ume is twice that of hydrogen, the specific gravity of the gas is equal to the specific gravi- ty of hydrogen multiplied by half the atomic weight of the gas. The proportions of two in- gredients in a compound, as in an alloy of gold and silver, may be found by multiplying the specific gravity of each ingredient by the dif- ference between it and the specific gravity of the compound. As the sum of the products is to the respective products, so is the specific gravity of the body to the proportions of the ingredients ; then as the specific gravity of the compound is to the weight of the compound, so are each of the proportions to the weight of its material. The following table presents the specific gravities of substances most likely to be referred to, collected from various sources. The weight of a cubic foot in ounces avoirdu- pois is seen by moving the decimal point three figures to the right. TABLE OF SPECIFIC GRAVITIES. Acid, acetic 1-062 .irs.-nir 3-891 boracic, crystallized 1-479 boracic, fused citric hydrochloric 1-084 1-200 nitric 1-271 to 1-588 aquiaregia 1-284 phosphoric, liquid . 1-658 phosphoric, solid . . 2-800 sulphuric 1-841 Alabaster 1-874 Alcohol, absolute 1 792 of commerce 0-885 Ale or beer 1-085 Alum 1-724 Aluminum.... 2-560 to 2-670 Amber 1-064 to MOO Ambergris .... 0'780 to 0^26 Amethyst, common. . . 2-750 oriental, or violet sapphire. 8-809 to 4-1 60 Ammonia 0-876 Anthracite . Antimony . Asphaltum 0-876 1-860 to 1-850 6-702 0-905 to 1-650 4-000 Cadmium 8-600 Caoutchouc 0-938 Chalk 2-784 Cinnabar 8-998 Clay 1-980 Coal,bituminous 1-020 to 1-350 Cobalt, cast 7-812 Copal 1-045 Copper, native 8-940 cast 8-788 wire 8-878 coin 8-915 Coral 2-540 to 2-850 Diamond 8'521 to8'550 Dolomite 2-540 to 2 -830 Earth, mean of the globe 5-210 sulphate of (heavy par).... 4 800 to 4-720 2-864, 0-956 to 0-964 Bismuth 9-82-2 Brandy 0-887 Brass 7-824 to 8-896 wire 8-644 Emerald 2-678 to 2-775 Ether.sulphuric 632 to 0'775 Fat of beef 0-928 Feldspar 2-400 to 2 "620 Freestone 2-148 Garnet 8-150 to 4-800 Glass, bottle 2-783 crown 2-520 preen 2-642 flint 2-760 to 8'829 plate 2-760 plate of St. Oobain. 2-488 Gold, native. 15-600 to 19-500 pure, cast hammered coin 22 carats fine. 20 carats fine . , Brick 1-900 to 2-000 ! Granite, Quincy Bronze, gun metal.... 8-700 Staten island! , w Jiutu ' r 942 , Graphite 1-9S7 to 2'400 19-258 19-362 17-647 17-4^6 15-709 2-652 2-780 Grindstone ........... 2-143 Gunpowder, loose, -j to [JS close shaken 0-937 to I'OOO solid ....... 1-550 to 1-800 Gum arable ........... 1-452 Gypsum, compact. -j to J'Hl Heliotrope or blood- stone ...... 2-630 to 2-700 Hematite iron ore. Honey ............... 1-456 Hyacinth ...... 4-000 to 4-750 Ice .................. 0-930 Iodine ................ 4-948 Iridium, hammered... 28-000 Iron, malleable. 7'645to7'S17 cast ............... 7-207 ore, magnetic 4-900 to 5'200 Ivory ......... 1-822 to 1-917 Lard ................ 0-947 Lead, cast. . . . 11-850 to 11-445 white ............. 7-235 ore, galena.. 7-250 to 7-780 Lime, quick .......... 0-804 Limestone, com- j 2-886 pact .......... 1 to8-000 crystallized ....... 2-722 Magnesia, carb. 2-222 to 2-612 Malachite ..... 8-700 to 4-000 Manganese ore (psilo- melane). . . 3'700 to 4-330 Marble, Carrara ...... 2-716 Parian ............ 2-837 Egyptian ......... 2-668 Mercury, common 13-568 pure ............... 14-000 Mica .......... 2-750 to 3-100 Milk .......... 1-082 Myrrh ............... 1-360 Naphtha ...... 0-700 to 0-847 Nickel, cast .......... 8-279 Nitre (saltpetre) ...... 1-900 Oil, castor ........... 0-970 linseed ............ 0940 olive ............. 0-915 turpentine ........ 0-870 whale ............. 0-923 Opal ................. 2-114 Opium ............... 1837 Palladium ........... 11-800 Pearl, oriental. . 2-510 to 2-750 Peruvian bark ....... 0-784 Pewter .............. 7-471 Phosphorus .......... 1-770 Platinum, native. refined ............ 19-500 hammered ........ 20-836 wire .............. 21-041 laminated ......... 22-069 Porcelain, China ...... 2-385 Sevres ............ 2-145 Porphyry ..... 2-458 to 2-972 Potassium ........... 0-865 Proof spirit .......... 0-923 Quartz ........ 2-500 to 2'800 Rhodium ............ 11-000 Rosin ................ 1-100 Ruby ................ 4-283 Salt, common ........ 2'130 Sand ......... 1-500 to 1-800 Sapphire, oriental ____ 8'994 Serpentine ____ 2 '507 to 2'59l Silver, pure, cast ..... 10-474 hammered ........ 10-510 coin .............. 10-534 Slate ......... 2-110 to 2'672 Soapstone ..... 2-650 to 2-800 Sodium .............. 0-972 Spermaceti .......... 0-943 Steel, hard ..... 7-816 to 7-340 soft ............... 7-S33 Sugar ................ 1-606 Sulphur, native ...... 2-033 fused ............. 1-990 Tallow ............... 0-941 Tar ................. 1-015 Tellurium ..... 5-700 to 6-115 Tin, cast ............. 7291 hardened ..... 7-299 Topaz ......... 3-400 to 3-650 Tourmaline. . . . 2-940 to 8-300 Tungsten ............ 17-400 Turquoise ..... 2-600 to 2 '830 Ultramarine .......... 2-362 Vinegar ....... 1-013 to 1 080 Water, distilled ...... 1-000 sea ............... 1-023 Dead sea .......... 1-240 Wine, Burgundy ..... 0-991 white champagne . . 0-99T Wood (see tables in article FUEL). Zinc, cast ............ 7'190 GRAY, a town of France, in the department of Haute-Sa6ne, on the left bank of the river Saone, 30 m. S. W. of Vesoul ; pop. in 1866, 6,764. It is on a hill, in the form of an amphi- theatre, and the streets are narrow, but the town is pretty well built. The river is spanned by a suspension bridge and one of stone. There are a college, a public library, and a theatre. The chief manufactures are hair cloth, wool- len goods, leather, and starch. In the environs are several iron works. Gray is a very an- cient town, and was the last place in Franche- Comte which submitted to Louis XIV. in 1668. GRAY, Asa, an American botanist, born in Paris, Oneida co., K Y., Nov. 18, 1810. He graduated at the Fairfield medical college in 1831, but abandoned the practice of medicine, and applied himself to the study of botany. In 1834 he was appointed botanist to the United States exploring expedition ; but as some time elapsed before it was ready to sail, he resigned that situation. In 1842 he was elected Fisher professor of natural history in Harvard college. In his numerous writings he has shown equal ability in communicating elementary knowl- edge and in elucidating recondite theory. His elementary works, " Elements of Botany," pub-
