To prepare the ether bring 5½ parts of powdered potassium dichromate together with 5 parts of water into a distilling apparatus and very gradually add a mixture of 1 part amyl alcohol and 5 parts concentrated sulphuric acid. The fluid becomes so strongly heated that it almost boils. When reaction is finished, heat and distil off the rest. The distillate consists of two layers; the lower one being an aqueous solution of valerianic acid and the upper one a mixture of valerianic acid and amyl valerate. To separate both, add concentrated carbonate of soda solution until all the free acid is neutralized. The oily liquid separating thereby is the ether. It is separated from the valerianate of sodium, the latter evaporated to a small volume, and, after cooling, sufficient sulphuric acid to fix the entire quantity of the soda is added. The valerianic acid is thereby separated, and floats upon the solution of the sodium sulphate. It is separated from the latter, and 1¼ parts of it are added to a mixture of ¾ part of amyl alcohol and 1 part sulphuric acid and heated to 212° F. After the addition of water, the apple-ether separates and only requires washing with water and some sodium carbonate to yield a pure product. The separation of the valerianic acid can, however, be readily avoided. Evaporate the neutral solution of the valerianate of soda to dryness in the water-bath, weigh off 1 molecule, or 124 parts, and gently heat it with a mixture of 1 molecule or 98 parts of sulphuric acid (on account of the content of water in the commercial acid, 105 parts of it will have to be taken) and 1 molecule or 88 parts of amyl alcohol. The ether thus obtained is a fluid, which, in a concentrated state, does not possess an agreeable odor, but when mixed with 10 parts of alcohol imparts to the latter an odor resembling that of apples. It boils at from 370° to 374° F., and at 64° F. has a specific gravity of 0.8793. _Valerianic ethyl ether_ closely resembles the amyl ether, and, like it, is prepared from valerianate of sodium, ordinary alcohol, and sulphuric acid. _Apple ether_ essentially consists of valeric amyl ether, of which 1 part is dissolved in 6 to 10 parts of strong alcohol. _Apricot ether_ is butyric ether with some amyl alcohol. _Cherry ether_ is acetic ether with benzoic ether. _Pear ether_ contains acetic amyl ether. _Pineapple ether_ is butyric ether. _Strawberry ether_ is acetic ether with acetic amyl ether and butyric ether. The ethers are dissolved in various proportions in alcohol, according to the intensity of the odor which it is desired to obtain. The aroma of most of them is generally increased by a slight addition of chloroform. For the preparation of different fruit essences Kletzinsky[10] gives the following directions. The figures indicate additions in cubic centimeters to 1 liter of rectified alcohol of 90 per cent.:-- [10] Dingler's Polyt. Journ., 180, 77.