4322. Nitro-Benzole

4322. Nitro-Benzole. A yellowish, oily fluid, insoluble in water; boils at 415° Fahr., and has a specific gravity of 1.209; known also as essence of mirbane. The method of preparing it is as follows: Place 10 parts fuming nitric acid in a tubulated retort capable of holding 3 times the quantity; apply heat sufficient to produce gentle ebullition. Insert a glass tube through the upper neck of the retort, and through it introduce by degrees, a drop at a time, benzole (not benzine, see No. 4321 (Benzole)), so long as nitrous vapors are evolved; the liquid which passes into the receiver being poured back from time to time into the retort. When the red vapors have ceased to rise, distill off the excess of benzole, if any, from the acid. Then pour the contents remaining in the retort into 120 to 150 parts cold water, and let it stand for a few days, when the nitro-benzole will be found separated at the lower part of the vessel. Decant the upper stratum of acid, wash the nitro-benzole with water, and keep it in stoppered bottles. This substance is used as a factitious oil of bitter almonds, being, although poisonous, far less so than the prussic acid of which the real article consists. (Hager.)

4323. Urea

4323.     Urea. A crystalline, colorless, transparent substance, consisting of cyanate of ammonia. Fresh urine, gently evaporated to the consistence of a syrup, is to be treated with its own volume of nitric acid at 24 deg.; the mixture is to be shaken and immersed in an ice-bath to solidify the crystals of nitrate of urea; these are washed with ice-cold water, drained, and pressed between sheets of blotting paper. When they are thus separated from foreign matters, they are to be dissolved in water to which subcarbonate of potash is added, whereby the nitric acid is taken up, and the urea set at liberty. This new liquor is evaporated at a gentle heat, nearly to dryness; the residue is treated with pure alcohol, which only dissolves the urea; the solution is concentrated, and the urea crystallizes. ( Thénard.)

Or: Mix 28 parts of perfectly dry ferrocyanide of potassium with 14 parts of black oxide of manganese, both pure and in fine powder; then place them on a smooth iron plate, and heat them to a dull red, over a charcoal fire. "When the mass begins to burn, it must be frequently stirred; after which cool and dissolve in cold water, filter, and add 201/2 parts of dry sulphate of ammonia, and decant the clear from the precipitated sulphate of potassa. Concentrate at a heat be-low 212°, again decant, evaporate to dryness, and digest in boiling alcohol of 80%; crystals of urea will be deposited as the solution cools. (Liebig.)

4324. Nitrate of Urea

4324.    Nitrate of Urea. This may be prepared as in last receipt from urea; or by saturating the artificial urea (Liebig's preparation) with nitric acid.

4325. Stearine

4325.     Stearine. The solid portion of fats which is insoluble in cold alcohol. Pure strained mutton suet is melted in a glass flask with 7 or 8 times its weight of ether, and the solution allowed to cool; the soft pasty mass is then transferred to a cloth, and is strongly pressed, as rapidly as possible, to avoid evaporation; the solid portion is then dissolved again in ether, and the solution allowed to crystallize. The product is nearly pure.