added, and a drop or two of HC1, and the whole left on the 

 steamer to dry. The moist residue is washed out into a 

 porcelain crucible with 80% alcohol. It should, of course, be 

 washed on a filter first until the filtrate comes out colourless. 

 The curcible is left on the steamer to dry, and afterwards 

 in the water-oven. When cool, it is weighed. 



(7) Phosphorus- Pentoxide. The jelly like precipitate al- 

 ready mentioned is transferred into a beaker with the help 

 of the wash-bottle. Some Nitric Acid is poured on to the 

 filter to dissolve the adhering precipitate. The filtrate is 

 collected in the same beaker containing the precipitate. The 

 frlter-paper is once more filled with HNO 3 when it is empty. 

 A test-tube and a half of an acidified solution of Ammonium 

 Molybdate is then added. The mixture is left uncovered in 

 the sand-bath, to get concentrated. The bright yellow preci- 

 pitate is collected on a filter-paper. The filtrate is treated with 

 a little more of ammonium molybdate to see if any more yellow 

 precipitate would form. The precipitate on the filter is 

 washed with Ammonium Nitrate. It is then treated on the 

 filter with just enough of dilute ammonia solution to dissolve 

 the precipitate. A few drops of citric acid should be added to 

 the filtrate and some MgSO 4 mixture. It should be then left 

 covered up in a cold place for 12 hours. The precipitate is 

 collected on a filter-paper, washed with NH 3 -water until the 

 filtrate is not rendered turbid with BaCl 2 . The precipitate 

 is dried, ignited, first gently, then before the blow-pipe, 

 cooled, and weighed. 



1.402. The determination of available phosphoric acid 

 and potash has been already described (pp. 559 and 560). 



1.403. The following weights etc., were actually obtained, 

 in an analysis of a sample of soil : 



Moistw 



Watch-glasses and clip and raw soil =27*3707 grams 

 Watch-glasses and clip ... =24-3707 * 



