CIRCULAR No. 4. (To accompany Bulletin No. 46.) 



United States Department of Agriculture, 



DIVISION OF CHEMISTRY. 



WASHINGTON, D. C., December 11, 1897. 



All the changes in methods of analysis of the Association of Official Agricul- 

 tural Chemists, which were made at the annual meetings of 1896 and 1897, have 

 been incorporated in Circular No. 4. In this circular, the pages in the edition 

 of Bulletin 46, where the methods described would naturally be found, are indi- 

 cated. By this arrangement, the expense of entirely reprinting Bulletin 46 has 

 been avoided without sacrificing, to any appreciable extent, the availability of 

 the methods. 



This circular will be furnished to all members of the Association of Official 

 Agricultural Chemists and to others in so far as the extent of the edition will 

 permit. 



H. W. WILEY, 



Chief of Division, Secretary A. O. A. C. 

 Approved : 



JAMES WILSON, 



Secretary. 



CHANGES IN AND ADDITIONS TO METHODS OF ANALYSIS ADOPTED 

 AT THE THIRTEENTH AND FOURTEENTH ANNUAL MEETINGS OF 

 THE ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS. 



[In all cases, unless otherwise mentioned, pages and paragraphs cited refer to Bulletin No. 46, 

 Chemical Division of the United States Department of Agriculture. H. W. W.] 



DETERMINATION OF PHOSPHORIC ACID. 



Page 14 (2) (b) (b^, eighth line, omit "six," and insert "from ten to fifteen." 

 Sixteenth line, omit all after "wash" to end of sentence and insert "from five 

 to six times with water, using in all from 150 to 250 cc." 



5. DETERMINATION OF POTASH. 

 (Insert instead of methods on pages 22, 23, and 24. ) 



(a) LINDO-GLADDING METHOD. 



(1) Preparation of reagents. 



(a) Ammonium chlorid solution. Dissolve 100 grams of ammonium chlorid 

 in 500 cc of water, add from 5 to 10 grams of pulverized potassium platinic 

 chlorid, and shake at intervals for six or eight hours. The mixture is then 

 allowed to settle over night and filtered, and the residue is ready for the prepara- 

 tion of a fresh supply when needed. 



(b) Platinum solution. The platinum solution used contains 1 gram of metal- 

 lic platinum (2.1 grams of H 2 PtCl 6 ) in every 10 cc. 



