MISCELLANY. 
Preparation of Urea. — The usual method of preparing urea, by precipi- 
tating it from urine by means of nitric acid, is attended with great ex- 
pense of time and material. 1 Professor Liebig has recently published the 
following new and easy method : 
Twenty-eight parts of perfectly dried ferrocyanate of potash are mixed 
with fourteen parts of the black oxide of manganese, both finely powdered, 
the mixture heated on a smooth iron plate (not in a crucible,) over a coal 
fire to incipient redness, stirring frequently. The mass on cooling is 
washed out with cold water, and the liquid mixed with twenty and a half 
parts of dry sulphate of ammonia. It is advantageous to place aside the 
first strong ley obtained, and to dissolve the sulphate of ammonia at the 
common temperature, in the last water, and to add this to the first con- 
centrated solution. Usually a strong precipitate of sulphate of potash is 
immediately formed, from which the liquid is separated by decantation; 
it is then evaporated in a water bath, or on some warm place, boiling 
being avoided, and the liquid poured off as long as it is possible from the 
deposite of sulphate of potash. It is then evaporated to dryness and 
treated with boiling alcohol of 80 to 90 per cent., which dissolves the 
urea, while the sulphate salts remain undissolved. In this manner four 
ounces of perfectly colorless and beautifully crystallized urea may be ob- 
tained from a pound of the ferrocyanate of potash. It frequently happens 
that the solution containing the sulphate of potash and urea is colored yel- 
low by ferrocyanide of ammonium, or potassium, which dissolves in the 
alcohol and gives to the crystals of urea a yellowish color; it may easily 
be separated by the addition of a solution of copperas; after the separation 
of the prussian blue, carbonate of ammonia is added to the liquid, which 
decomposes the excess of iron salt, and the liquid becomes clear and color- 
less, and may be evaporated and treated as above. — August No. of Lori' 
don, Edinburgh, and Dublin Philosophical Magazine, from Ann. de Chem. 
and Pharm. vol. xxxviii. part 1. 
Preparation of Azotic Gas. By M. Pelouze. — M. A. Rose has observ- 
ed that monohydrated sulphuric acid combines directly with nitric oxide, 
