164 Journal of Agricultural Research voi.xx,No. 3 



fusion method. The fusions were made over alcohol flames, and the 

 sulphate was precipitated as barium sulphate, usually from the solution 

 of the entire mass used in making the fusion. Total phosphorus was 

 determined by treating 1 to 2 gm. of the dry material with a solution of 

 magnesium nitrate, evaporating to dryness, igniting, and proceeding 

 in the usual manner. Chlorin was determined in a special portion of the 

 ash made by igniting at a low heat 5 to 10 gm. of the dry material, dis- 

 solving the residue in dilute nitric acid, and proceeding with the Volhard 

 volumetric method. In some cases chlorin was also determined by per- 

 forming the incineration in the presence of an excess of sodium carbonate 

 in order to avoid the possible loss of chlorin, but the results of the two 

 methods were similar. 



For the determination of total ash, 10 to 20 gm. of the dry samples 

 were incinerated in porcelain dishes over Bunsen burners. The material 

 charred easily and burned quietly upon the application of low heat and 

 was reduced to a gray ash without approaching dull redness. The 

 residue was then allowed to cool, was taken up with hot water, trans- 

 ferred to a filter, and washed thoroughly. The insoluble material with 

 its filter paper was transferred to a platinum dish, dried, pulverized 

 with an agate pestle, and heated to full redness. When the platinum 

 dish cooled, the filtrate from the previous leaching was added and 

 evaporated to dryness. Ten to 20 cc. of strong ammonium-carbonate 

 solution were then added, and the treatment was repeated until the 

 ash was completely carbonated, as was indicated by constant weight 

 upon evaporating to dryness and heating gently. The results are re- 

 corded as percentages of ash. It should be stated that the ash thus 

 obtained differs from that reported by other investigators in that we are 

 dealing with completely carbonated ash, whereas previous analyses of 

 citrus leaf ash have been calculated to a carbon-dioxid-free basis. 



The ash was dissolved in water and dilute hydrochloric acid, and the 

 solution was evaporated to complete dryness on the water bath in order 

 to dehydrate the silica. The amount of uncombined carbon found in 

 the ash was always entirely negligible. The residue was taken up with 

 warm water and dilute hydrochloric acid. The silica was determined 

 by the loss in weight occasioned by treating the incinerated residue with 

 hydrofluoric acid. The material nonvolatile in hydrofluoric acid usually 

 amounted to only 0.1 to 0.2 per cent of the ash and was neglected in 

 this work. The filtrate from the silica separation was made up to a 

 definite volume, usually 500 cc, and the various constituents were 

 determined in aliquots representing from 0.2 gm. to 0.4 gm. of the ash. 



The methods of the Association of Official Agricultural Chemists ' 

 were used with slight modifications, as noted. Iron, aluminum, and 



■Wiley, H. W., ed. official and provisional methods of analysis, association of official agri- 

 tural chemists. As compiled by the committee on revision of methods. U. S. Dept. Agr. Bur. Chem. 

 Bui. 107 (rev.), 272 p., 13 fig., 190S. Reprinted in 1912. 



