82 PRACTICAL AGRICULTURAL CHEMISTRY [267 



Note |, — Made by rendering a strong solution of citric acid dis- 

 tinctly alkaline with ammonia. 



Note 2.— Measure ioo c.c. water into a large flask, add 50 grams 

 molybdic acid or 70 grams of ammonium molybdate, then 100 c.c. of 

 strong ammonia ; stir until dissolved. Pour the solution into 720 c.c 

 cold nitric acid, sp. g. 1 "20, stirring whilst adding. 



Note 3.— Best kept as two solutions, A and B : A contains about 

 35 grams of copper sulphate dissolved in 500 c.c. of water, B contains 

 173 grams of Rochelle salt (sodium potassium tartrate) and 160 grams' 

 of potassium hydrate in 500 c.c. of water. For immediate use equal 

 quantities of each are mixed. 



267.— Reagents for General Use for the Detection 

 of Metals 



