PARIS GREEN 627 



Insecticides for External Biting Insects. This group of in- 

 secticides includes paris green, green arsenoid, arsenate of lead, 

 london purple, etc. 



529. Paris 'Green. Paris green is supposed to be copper-aceto 

 arsenite and to contain 31.29 per cent, copper oxid, 58.65 per 

 cent, total arsenious oxid and 10.06 per cent, acetic acid. On 

 account of its method of manufacture it may contain small 

 amounts of dust (determined as sand), small amounts of sodium 

 sulfate, and larger or smaller amounts of free arsenious oxid. The 

 following constituents therefore are usually determined in the 

 complete analysis of a sample of paris green : Moisture, sand, sul- 

 furic acid calculated as sodium sulfate, total arsenious oxid, 

 total copper oxid, soluble arsenious oxid and acetic acid by dif- 

 ference. 



Analyses of Paris Green. Moisture. Dry one to two grams 

 for eight to 10 hours at 105 to 110, and calculate the loss as 

 moisture. 96 



Total Arsenious Oxid. Method 7. 97 Solutions Required. (a). 

 .Starch Solution. Use a starch solution which is prepared by 

 boiling two grams of starch with 200 cubic centimeters of dis- 

 tilled water for about five minutes. 



(b) Standard Iodin Solution. Prepare a standard iodin solu- 

 tion in the following manner: Dissolve 12.7 grams of pow- 

 dered iodin in about 250 cubic centimeters of water to which 

 has been added about 25 grams of chemically pure potassium 

 iodid, and make up the whole to a volume of two liters. To 

 standardize this solution, weigh one gram of chemically pure 

 dry arsenious oxid, transfer to a 250 cubic centimeter flask by 

 means of about 100 cubic centimeters of a solution containing 

 two grams of sodium hydroxid in each 100 cubic centimeters, 

 and boil until all arsenious oxid goes into solution. Make up 

 to a volume of 250 cubic centimeters and use 50 cubic centi- 

 meters for analysis. Concentrate this portion of 50 cubic cen- 



96 Bureau of Chemistry, Bulletin 107, 1907 : 25. 



97 Smith, Journal of American Chemical Society, 1899, 21 : 769. 



Hay wood, Journal of the American Chemical Society, 1900, 22 : 568. 

 70S- 



