Appendix 231 



4. The sediment from which the "clay" has been removed is 

 worked up as before in the beaker, which is filled to the 10 cm. 

 mark and allowed to stand for 100 seconds. The operation is re- 

 peated till the "fine sand" settled in 100 seconds is clean, when it 

 is collected, dried and weighed. 



5. The turbid Uquid poured off from the "fine sand" is collected 

 in a Winchester quart, or other suitable vessel, allowed to settle, 

 and the clear hquid syphoned or decanted off. The sediment is then 

 washed into the marked beaker and made up to the 7'5 cm. mark. 

 After stirring, it is allowed to settle for twelve and a half minutes; 

 and the liquid decanted off. The operation is then repeated as before 

 till all the sediment sinks in twelve and a half minutes leaving the 

 liquid quite clear. The sediment obtained is the "silt" which is dried 

 and weighed as usual. The hquid contains the "fine silt," which, 

 when it has settled down, can be separated by decanting off the!" 

 clear liquid and dried and weighed. 



6. Determinations are made of the "moisture" and "loss on 

 ignition" of another 10 grams of the air-dry earth. The sum of the 

 weights of the fractions after ignition + loss on ignition + moisture 

 -I- material dissolved in weak acid should approximate to 10 grams. 

 The sizes of the particles thus sorted out are as follows: 



Fine gravel ... ... Above 1 mm. 



Coarse sand 



Find sand 



Silt 



Fine silt . . 



Clay 



1 to 0-2 mm. 

 0-2 to 0-04 mm. 

 0-04 to 0-01 mm. 

 0-01 to 0-002 mm. 

 Below 0-002 mm. 



Analysis of manures 



The following are the official methods commonly adopted in this 

 country : 



Thoroughly mix the sample, and if possible, pass it through a 

 1 mm. sieve. The percentage of moisture is determined by drying 

 a weighed sample at 100 C. 



Nitrogen, {a) In the absence of nitrates and ammonium salts. 

 A weighed quantity of the sample is put into a Kjeldahl flask with 

 10 grm. of potassium sulphate and 25 c.c. of concentrated sulphvuric 

 acid; the flask is heated till the contents become colourless or of a 

 light straw colour. The operation may be accelerated by adding a 



