When distilled, after drying over CaCl_{2}, the boil begins to pass over at 140 degrees C., accompanied by a few drops of aqueous fluid, the temperature constantly and rapidly rising to about 240 degrees, the chief portion of the oil coming over between 240 degrees and 270 degrees C. and a little passes over between 270 degrees and 300 degrees, but evidently accompanied by decomposition products, a transparent, brown, tenacious, semi-solid residue remaining in flask. The lower boiling products retain the ginger aroma, which is noted when diluted with spirits, and are much more soluble in rectified spirits than higher fractions. Oil of ginger is yellow in color and its odor is intensely like that of the root; that of Jamaica is the most fragrant, but has not the burning, pungent taste of ginger, which is due to gingerol, the active pungent principle of the root. Gingerol exists in the dried rhizomes to the extent of from 0.600 to 1.450 per cent. It is of a pale straw color and odorless, with a pungent, bitter taste. It is soluble in alcohol in even 50 per cent. dilution; it is also soluble in benzene, volatile oils, carbon disulphide, solution of potash and ammonia, and glacial acetic acid, and very slightly soluble in petroleum ether, consisting of resin, starch, mucilage, and paraffine, organic acids, oxalic acids as CaC_{2}C_{4} cellulose albuminoids, etc., which constituents of ginger are found to be odorless and tasteless. The alcoholic solution is neutral in reaction and gives no precipitate with the acetates of lead nor with lime, and does not yield glucose when treated with diluted sulphuric acid. Strong sulphuric acid dissolves it with the production of a brown color; hydrochloric acid does not affect it. Nitric acid converts it into a blood-red resinous substance. Adulterants of ginger are sago, tapioca, flour of rice, wheat, and potatoes, Cayenne and mustard hulls, and tumeric and exhausted ginger. The foreign starches, Cayenne, and mustard hulls are easily detected, but the tumeric (East India arrowroot) cells, from their resemblance to the resin globules of the ginger, are most confusing. For detection of exhausted ginger recourse must be had to proximate analysis. Chemical composition of ginger: Ash may vary from 3.4 to 8 per cent.; fiber, 1.7 to 9 per cent. The white ginger has less ash than the dark, as is also the case in regard to the percentage of fiber. Water, 11.00 to 9.10 Ash, 7.02 to 3.39 Volatile Oil, 2.54 to .96 Fixed Oil, 4.58 to 2.29 Starch, 53.33 to 46.16 Crude Fiber, 7.65 to 1.70 Albuminoids, 10.85 to 5.25 It is said that the water and starch extract from the weight of the newly dug root 75 to 85 per cent., and yet the dried root retains all the valuable aromatic qualities.