20 TAEMEES BULLETIN 846. 



off. Sodium cyanid at present is used for fumigation more generally 

 than is potassium cyanid and is more readily obtained. 



Dosages to use. — Sodium cyanid should be combined with acid and 

 water to generate the hydrocyanic-acid gas, according to the follow- 

 ing formula : 



Sodium cyanid (grade guaranteed to contain not less than 51 per cent of 



cyanogen and practically free from chlorin) avoirdupois ounce__ 1 



Sulphuric acid (commercial*) fluid ounces__ 1^ 



Water do 3 



Should potassium cyanid be used in place of sodium cyanid,^ the 

 cyanid should be combined with sulphuric acid and water according 

 to the following formula : 



Potassium cyanid (98 to 99 per cent grade and guaranteed to contain not 



less than 38.4 per cent cyanogen) avoirdupois ounce — 1 



Sulphuric acid (commercial * I fluid ounce__ 1 



Water fluid ounces 3 



The amount of chemicals given in either of these formulas is suffi- 

 cient for the fumigation of 100 cubic feet of space in the fumigation 

 closet or room. The exposure to fumigation should last at least 

 24 hoilrs. Best results are obtained by fumigating at temperatures 

 above 70° F. For general use 4 ounces of cyanid, either of sodium 

 or potassium, to 100 cubic feet will be found fairly satisfactory. This 

 dosage when sodium cyanid ^ is used requires 4 ounces of cyanid, 

 6 fluid ounces of sulphuric acid, and 12 fluid ounces of water. The 

 cyanid is weighed, and the liquids, sulphuric acid, and water are 

 measured. 



For generators use earthenware jars, and these should be deep 

 enough to prevent the liquid from boiling over. Since the gas gener- 

 ated is lighter than air, j)lace the generator underneath the material 

 to he fumigated or an the floor of the room. Place the chemicals for 

 fumigating in the generating jar in the following order: First., xoater; 

 then sulphuric acid; last, just hefore closing the fumigating closet or 

 room., the cyanid. Do not your water on to the acid. Avoid hreath- 

 ing the gas., as it is deadly poisonous. The reaction of the chemicals 



^ Commercial sulphuric acid (about 1.84 sp. gr. or 66° Baume) which is approximately 

 93 per cent pure is commonly used for fumigation. 



-The yield of hydrocyanic-acid gas from 1 ounce of high-grade sodium cyanid is 

 equivalent to the yield from approximately IJ ounces of high-grade potassium cyanid. 



* Sodium cyanid is now on the market in molds or " eggs " weighing 1 ounce each. 

 It is advisable to use this form, since it is easily handled and the necessity for weighing 

 is obviated. The poison should be kept in tight cans, properly labeled, and extreme care 

 should be taken in handlinj/ it. .Sodium cyanid and potassium cyanid are among the 

 most poisonous substances known. 



