6 
SINAPIS ALBA. 
Prussic Acid is prepared for medicinal purposes by tlie London 
Apothecaries' Company, from cyanuret of mercury, lljj.; Hydro- 
chloric Acid, ibj.; and water, Itev. Four pints are drawn oft' and 
rectified through chalk. 
Chemical Properties of Prussic Acid. This acid, in its 
most concentrated state, is a transparent colourless fluid, with a 
stroHg smell, similar to that of peach blossoms, or bitter almond 
trees ; its taste acrid ; it scarcely reddens the tincture of turnsole ; 
exposed to the action of caloric, it boils at 26° 5': and congeals at 
15° below 0 ; it inflames on approaching a body in a state of com- 
bustion ; but little soluble in water; readily dissolves in alcohol; 
with nitrate of silver it gives a white precipitate ; combined with 
potash and oxyde of iron, it furnishes a double salt, of a lemon 
colour, which dissolves in water, and the solution of which throws 
down in a blue precipitate, more or less deep, the salts of iron of 
the Second and third degree of oxydation. For a full account of 
the chemical properties of this acid, we refer our readers to a 
memoir on the subject, by M. Gay Lussac. Annales de Chimie, 
torn. Ixxvii. p. 128. 
^ 
SINAPIS ALBA. 
White Mustard.* 
Class Tetradynamia. — Order Siliquosa. 
Nat. Ord. Siliquosa, Linn. Sisymbri^, Juss. 
Gen. Char. Calyx expanding-; Claws of the Coral straight. 
Gland between the shorter stamens and pistillum and between 
the longer and the calyx. 
Spec. Char. Siliques hispid. Beak oblique long sword form. 
The white Mustard, and several species of the Genus Sinapisf, 
are indigenous to Britain. The Sinapis Alba is chiefly cultivated for 
* Fig. a. in the annexed specimen, represents a spike of flowers of the natural size. 
b. A magnified pistillum. c. Stamina, magnified, d. Glands, e. Caljix. 
t Nineteen species of the Genus Sinapis are known and cultivated in England. (Vide 
Hort. Cant.) 
