A stone-ware flask of at least 120 lbs. capacity, such as is used for the preparation of chlorine, is so placed upon a tripod in a sheet-iron cylinder that the neck projects over the edge of the cylinder. The space between the flask and the walls of the cylinder is completely filled with mats or coarse pack-cloth. A steam-pipe enters the lower part of the cylinder, while a cock placed on the bottom of the cylinder serves for discharging the condensed water. The cylinder is closed by a sheet-iron cover provided in the centre with a hole through which passes the neck of the flask. The flask is filled with 60 lbs of 90 per cent. alcohol free from fusel oil, to which, in small portions, 15 lbs. of crude nitric acid of 36° Bé. are added.
The neck of the flask is provided with an exactly-fitting tube of pure tin. The tube is bent twice at a right angle, and one end is provided with an annular piece to prevent it from slipping too far into the interior of the flask. The joints between the tube and the neck of the flask are luted with a stiff paste of flaxseed meal, a wet strip of linen being, for greater security, wrapped over the cement. The other end of the tin-tube, which here occupies the place of a still-head, is in the same manner connected with a long tin-worm lying in a large cooling vat.
Everything being prepared, but little steam is at first introduced into the iron cylinder in order to slowly warm the apparatus. When this is done the admission of steam is gradually increased. The mats or pack-cloth placed between the walls of the cylinder and the flask prevent the latter from bursting, which otherwise might readily happen. Distillation commences in about ten minutes. The admission of steam is then moderated, care being had that the ether passes over in an uninterrupted stream of the thickness of a goose-quill.
When, with the admission of the same amount of steam, the distillate commences to run drop by drop, the steam-cock is closed and the operation interrupted, this being the case in about six to seven hours.
The next day the flask—without removing the residue—is charged in the same manner. However, the third day only 30 pounds of alcohol are poured in.
The combined distillates come into a copper still with double walls, between which steam can be admitted, and are neutralized with dry calcium hydrate. The cooling pipe connected with the still consists of tin, and is provided with a beak dipping into a flask filled half-full with 4 pounds of alcohol. A slight current of steam suffices for distillation. The first distillate is dark yellow, and contains large quantities of aldehyde. Notwithstanding careful cooling, the vapors can be but incompletely condensed, and their inhalation has to be carefully avoided, they producing stupor and headache as well as inflammation of the eyes. When the distillate is colorless and shows no reaction with litmus paper, the receiver is removed and replaced by a large glass balloon in which the entire distillate is collected. Distillation must be quickly finished, as otherwise colored ether is obtained.
Valerianic amyl ether or amyl valerate, C5H11O.C5H9O.
This ether is formed by treating amyl alcohol with chromic acid. However, besides the ether a large quantity of valerianic acid is also formed, which has to be converted by itself into ether.
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.