Intelligence and Miscellaneous Articles. 567 



retort is connected by means of a bent tube with the U-shaped tube 

 b c; each arm of this tube is about 18 inches long and £ to f- of an 

 inch wide. It is filled with small pieces of fused chloride of cal- 

 cium, with the exception of the first one-third of b, which contains 

 small pieces of the above-mentioned black cyanide of potassium. 



This tube stands in a cylindrical vessel d of equal height ; from 

 the arm c proceeds a long and rather narrow conducting tube, bent 

 at a right, or any other convenient angle, into the vessel e ; by means 

 of the caoutchouc tubes ff, the apparatus is made more safe. When 

 the apparatus is thus disposed, and all the junctions and corks found 

 to be perfectly tight, the cylinder d is filled with ice-cold water, and 

 the small and narrow flask e, destined to receive the acid, is immersed 

 in snow or ice and salt up to the neck. 



A cold mixture of equal part3 of sulphuric acid and water is now 

 poured through the funnel into the cyanide of potassium in the 

 retort in very small successive portions ; for 2 parts of the melted 

 mass of cyanide of potassium 1 part of oil of vitriol is taken ; the 

 mass in the retort is so highly heated by this addition of the dilute 

 acid as to begin to boil ; the acid must therefore only be added at 

 long intervals, taking care that no air enters with it. It is probable 

 that a concentrated solution of tartaric acid would be preferable to 

 the sulphuric acid. During the addition of the sulphuric acid a 

 considerable quantity of prussic acid is developed, which would be 

 carried out of the apparatus along with air ; to avoid this the chlo- 

 ride of calcium tube is placed in cold water and the recipient in ice. 

 When all the acid has been added, and the fluid in the retort no 

 longer boils, the cold water is removed from the cylinder d by means 

 of a siphon, and replaced with water at a temperature of 85° to 90° F. 

 By this means the prussic acid previously condensed in the chloride 

 of calcium tube is evaporated, and passes into the recipient e ; at the 

 same time the contents of the retort are brought to gentle ebul- 

 lition, which is continued as long as prussic acid is disengaged. The 

 tube/ may be surrounded with ice also, when conveniently bent, so 



