ISOLATION OF CYANURIC ACID FROM SOIL 



By Louis E. Wise; and E. H. Walters, Biochemists, Soil-Fertility Investigations, 

 Bureau of Plant Industry, United States Department of Agriculture 



In the course of an investigation of an Indiana soil a nitrogenous 

 compound was isolated and shown to be cyanuric acid (PI. 1 1 ) . The isola- 

 tion of this compound was effected in the following manner : Twenty-three 

 kgm. of soil at a time were extracted with about 75 liters of 2 per cent 

 sodium-hydroxid solution at room temperature for 24 hours. The 

 alkaline extract was rendered slightly acid to litmus with sulphuric acid 

 and the acid liquor filtered. The clear acid filtrate was then washed 

 with ether to remove any aldehydes or other soluble acids present, and 

 then treated with an excess of mercuric sulphate in dilute sulphuric acid. 

 The flocculent mercury precipitate was washed by decantation, filtered 

 and washed, suspended in hot water and decomposed with hydrogen 

 sulphid. After the filtration of the mercuric sulphid, the dark-colored 

 filtrate was heated on the steam bath to expel sulphuretted hydrogen, 

 and was then treated with i or 2 c. c. of acetic acid. After cooling, this 

 solution was diluted to about 6 liters with water and treated with an 

 excess of a saturated aqueous solution of neutral lead acetate. 



The voluminous dark-brown precipitate thus formed was filtered and 

 washed with water. The filtrate was subsequently treated with a large 

 excess of concentrated ammonium hydroxid, and the resulting pale- 

 yellow precipitate was washed by decantation with very dilute ammonia, 

 and finally transferred to a fluted filter paper and washed with water. 

 The moist precipitate was suspended in hot water and decomposed with 

 a rapid stream of hydrogen sulphid.^ After filtration of the lead sulphid, 

 the straw-colored solution was concentrated to small volume, decolorized 

 with purified boneblack, filtered, evaporated to a brown sirup, and 

 allowed to crystallize. An organic substance then separated, crystal- 

 lizing in the form of flat plates or small prisms, frequently contaminated 

 with needles of calcium sulphate. The substance was either recrystal- 

 lized from water or from 50 per cent alcohol, the latter serving to separate 

 it from calcium sulphate. After repeated crystallization from water 

 the compound was obtained in the form of small glassy prisms of varying 

 shapes, which effloresced rapidly when allowed to stand in the air. 



The writers were able to establish the identity of the compound obtained 

 from soil with cyanuric acid by carefully comparing its properties with those 



' A tendency to form colloidal sulphid solutions at this point was sometimes noted. This was overcome 

 by the addition of a few crystals of lead acetate to the solution or by adding small amounts of purified 

 boneblack. 



Journal of Agricultural Research, Vol. X, No. 2 



Washington, D. C. July 9, 191 7 



iu Key No. G — 116 



(85) 



