120 EXPERIMENT STATION RECORD. 



Moisten the residue witli strong nitric acid and again evaporate to dryness. To 

 expel nitric acid, moisten the residue with hydrochloric acid and evaporate nearly 

 to drynei^s on the water bath, taking care to prevent the formation of crusts. Dry 

 the residue in an air bath for an liour, treat with warm water and 20 per cent solu- 

 tion of hydrochloric acid, wash into a 250 cc. flask, boil f<jr 15 minutes, and after 

 cooling till the tiask to tlie mark with distille<l water, and filter the solution. 



For the determination of lime add to 50 cc. of this filtered solution in a 250 cc. fiask 

 2 or 3 drops of rosolii--ai'id S( iluti(jn and ammonia from a dropping tube until a pinkish 

 color appears. Boil until the pink color almost disax)pears, thus i)recipitating alumina 

 and oxid of iron. After cooling, fill the flask to the mark, shake thoroughly, and 

 filter into a 300 cc. flask, the solution being made to the mark. To 100 cc. of this 

 filtrate add 3 to 5 drops of acetic acid and 20 cc. of a 4 per cent auunonium oxalate 

 solution. Keep on a water bath for 6 hours and filter through double filter papers. 

 Ignite the precipitate first over a Bun.sen flame, then heat strongly in a furnace for 

 10 minutes. This gives the weight of lime. 



To determine potash, boil 50 cc. of the original soil extract in a 2.50 cc. flask, add 5 

 cc. of a 10 per cent solution of barium chlorid and boil again for some time, aild a 

 few drops of rosolic acitl and ])oil with ammonia, as in case of the lime <letermination. 

 When partly cool add 2 or 3 gm. of crystalline annnonium carbonate and raise the 

 temperature at once to the boiling point to separate lime and l)arium. After complete 

 precipitation of the latter cool the liquid, fill the flask to the mark, and filter the 

 solution. Evaporate 100 cc. of this filtrate to dryness in a platinum dish on a water 

 bath, heat carefully to expel all ammonium salts, and wash the residue through a 

 filter with boiling water into a glass dish. Add 2 cc. of a 10 per cent solution of 

 platinum chlorid and evaporate to dryness on a water bath. After cooling add 80 to 

 82 per cent alcf)hol to the residue, allow to stand for at least half an hour, filter 

 through a Gooch crucible, using the filter jiump, and wash first with 90 per cent and 

 then with al)solute alcohol, drying tlie precipitate for 2 hours in a water oven. After 

 weighing the crucible, wash the doul)le salt through with boiling water, follow with 

 alcohol, dry, and weigh, taking the difference between the two weighings as the 

 amount of potassium platinum chlorid. This multiplied by 0.193 gives the quantity 

 of jjotash in 10 gm. of soil. 



To determine phosphoric acid, add 25 cc. of concentrated nitric acid to 25 gm. of 

 fine earth in a 500 cc. flask and shake thoroughly. Then add 50 cc. of concentrated 

 sulphuric acid and again shake the mixture carefully. Heat gently, shaking at fre- 

 quent intervals, and if this does not secure complete oxidation add njore nitrii- acid 

 and continue the heating. Cool the mixture, dilute to tlie mark with distilled water, 

 shake well, and filter. Nearly neutralize 200 cc. of the filtrate with strong ammonia 

 solution, a few drops of nitric acid Ijeing used to acidulate the mixture in case tlie 

 limit is exceeded. Add 200 cc. of molybdic solution prepared as follows: Dissolve 

 150 gm. of ammonium molybdate in a liter of water, adding 1 liter of nitric acid (sp. 

 gr. 1.2), and heat to a temperature of 50° C. for 3 hours in a water oven. Allow to 

 cool completely and decant the liquid through a small filter, washing the precipitate 

 in the flask with dilute molybdic solution. Dissolve the precipitate in warm 4 ])er 

 cent ammonia, acidulate .slightly with hydrochloric acid, and add 20 cc. of magnesia 

 mixture, drop by drop, at the rate of 1 cc. every 5 seconds, and then 25 cc. of 5 per 

 cent ammonia. Shake the mixture for a short time and allow to stand for 2 hours. 

 Filter through a Gooch crucible, wash with 5 per cent ammonia solution, dry first 

 on an iron plate, then ignite in a furnace for 15 minutes, cool, and weigh. 



Of the 212 samples of soil of which analyses are reported, only 45 contained nor- 

 mal amomits of lime, 167 were fairly supplied with lime, and 86 were tlecidedly poor 

 in this constituent. Only 15 contained a normal amount of phosphoric acid and 124 

 would be classed as poor in thi.^ constituent. As regards potash, 57 samples con- 

 tained normal amomits and 53 were poor. The results therefore indicate that the 



