25 



of silver ( AgN0 3 ), which may be obtained at almost any well-stocked 

 drug store. Dissolve the nitrate in cold water contained in a glass or 

 earthen vessel, using one-fourth of an ounce (Troy) of the crystals to 1 

 pint of water ; this dissolves in a few minutes, forming a whitish, semi- 

 transparent solution. The cyanide, when dissolved in water, forms a 

 transparent, nearly colorless solution ; when a small quantity of the 

 nitrate of silver solution is added to this it at first spreads out in a white 

 cloud, like milk, but it soon breaks up into small, white, floccy pistes 

 which gradually disappear upon being agitated, leaving the solution 

 nearly as transparent as at first; when more of the nitrate of silver 

 solution is added from time to time the above process is repeated, ex- 

 cept toward the last, when the cyanide solution becomes somewhat 

 milky, but it still remains semitransparent, permitting the operator to see 

 quite clearly the bottom of the vessel containing the solution. As soon 

 as a sufficient quantity of the nitrate of silver solution has been added 

 to the cyanide solution thelatter immediately becomes white and opaque, 

 like milk, completely concealing from view the bottom of the vessel con- 

 taining it. This completes the operation, and the quantity of nitrate 

 of silver solution used will indicate the strength of the cyanide tested. 

 When absolutely pure, 5§ grains of the potassium cyanide dissolved in 

 water will require 1 fluid ounce of the above nitrate of silver solution 

 before the turbidity occurs, indicating that the cyanide is 100 per cent, 

 strong; if only one-half of a fluid ounce of the nitrate of silver solution 

 produces this turbidity, this indicates that the cyanide in only half 

 strength, or 50 per cent, strong; if only one-fourth of a fluid ounce is 

 required, then the cyanide is 25 per cent, strong ; and so forth. The 

 nitrate of silver solution should be added to the cyanide solution very 

 slowly, the latter being agitated by gently shaking it each time that 

 any of the nitrate solution is added. Wherever any of the nitrate of 

 silver solution comes in contact with the skin or nails of the hand it 

 produces a reddish or black stain which can easily be removed by wash- 

 ing the stained part in a solution of potassium cyanide and water; this 

 will quickly remove the stain without causing any injury to the parts 

 affected, except, of course, when the stains occur upon a sore or cut in 

 the hand, in which case it would be very dangerous to apply the cyanide 

 to these places. 



It sometimes happens that the percentage of cyanogen (CIS or Cy)is 

 given, instead of the percentage of potassium cyanide (KCST or KCy) ; 

 but in cases of this kind the percentage of cyanide can be readily ascer- 

 tained by always bearing in mind that two-fifths of a given quantity of 

 potassium cyauide is cyanogen. Thus if a certain brand of cyanide 

 contains 24 per cent of cyanogen, this is equivalent to 60 per cent of 

 pure potassium cyanide. Potassium cyanide when absolutely pure 

 (equal to 100 per cent.) contains 40 per cent, of cyanogen; and, there- 

 fore, no grade of cyanide could contain a larger percentage of cyano- 

 gen than this. 



