REAGENTS AND SOLUTIONS 603 



Add 700 grams of concentrated ammonium hydroxide, mix thoroughly, 

 and preserve the mixture in a glass-stoppered bottle. 



Magnesium Nitrate Solution for Ignition. 1 Dissolve 320 grams of 

 calcined magnesia in nitric acid, avoiding an excess of the latter; then 

 add a little calcined magnesia in excess; boil; filter from the excess of 

 magnesia, ferric oxide etc., and dilute with water to 2 liters. 



Methyl Red. 2 Saturated solution in 50 per cent alcohol. 



Millon's Reagent. 3 Digest i part (by weight) of mercury with 

 2 parts (by weight) of nitric acid (sp. gr. 1.42) and dilute the resulting 

 solution with 2 volumes of water. 



Molisch's Reagent. 4 A 15 per cent alcoholic solution of a-naphthol. 



Molybdate Solution. 5 Dissolve 100 grams of molybdic acid in 144 

 c.c. of ammoniurn hydroxide (sp. gr. 0.90) and 271 c.c. of water; slowly 

 and with constant stirring pour the solution thus obtained into 489 c.c. 

 of nitric acid (sp. gr. 1.42) and 1148 c.c. of water. Keep the mixture in 

 a warm place for several days, or until a portion heated to 40 C. deposits 

 no yellow precipitate of ammonium phosphomolybdate. Decant the 

 solution from any sediment and preserve in glass-stoppered bottles. 



Morner's Reagent. 6 Thoroughly mix i volume of formalin, 45 

 volumes of distilled water, and 55 volumes of concentrated sulphuric 

 acid. 



Nakayama's Reagent. 7 Prepared by combining 99 c.c. of alcohol 

 and i c.c. of fuming hydrochloric acid containing 4 grams of ferric 

 chloride per liter. 



a-Naphthol Solution. 8 Dissolve i gram of a-naphthol in 100 c.c of 

 95 per cent, alcohol. 



Nessler-Winkler Solution. 



Mercuric iodide 10 grams. 



Potassium iodide 5 grams. 



Sodium hydroxide 20 grams. 



Water 100 c.c. 



The mercuric iodide is rubbed up in a small porcelain mortar with 

 water, then washed into a flask and the potassium iodide added. The 

 sodium hydroxide is dissolved in the remaining water and the cooled 

 solution added to the above mixture. The solution cleared by standing 

 is preserved in a dark bottle. 



1 Determination of phosphorus, p. 554. 



2 Determination of H ion concentration, pp. 158 and 480. 



3 Millon's reaction, p. 97. 



4 Molisch's reaction, p. 21. 



6 Detection and determination of phosphorus, pp. 129 and 554. 



6 Morner's test, p. 86. 



7 Nakayama's reaction, pp. 207 and 433. 



8 Oxidases p. 14. For other a-naphthol solution see Molisch reaction. 



