APPENDIX 93 



Iodine Solution (Wijs). Dissolve 13 grammes of 

 iodine in i litre of 95 per cent, acetic acid (but made 

 by diluting 100 per cent, acid with 5 per cent, of dis- 

 tilled water) ; pass in a current of chlorine till the 

 litre of the solution has been doubled ; this point is 

 indicated by a change of colour. 



Magnesia Mixture. Mix 60 grammes magne- 

 sium chloride (MgCl 2 60H 2 ), 145 grammes ammonium 

 chloride, 600 c.c. water, and 300 c.c. ammonia solution 

 (sp. gr. 0.880). 



Mercuric Nitrate Solution (Wiley). Dissolve mer- 

 cury in twice its weight of nitric acid (sp. gr. 1.42), 

 and, after solution, add an equal bulk of water. 



Nessler Solution. Dissolve 35 grammes of potas- 

 sium iodide in 100 c.c. of water ; set aside a few c.c. 

 of this solution, and add to the remainder a saturated 

 solution of mercuric chloride till a permanent red pre- 

 cipitate is formed ; add the small portion set aside, and 

 cautiously drop in mercuric chloride solution, till a 

 faint permanent precipitate is left. Dissolve 160 

 grammes of potassium hydroxide in water ; cool the 

 solution, and add it to the potassium mercuric icdide 

 solution. Make up to I litre, add a little mercuric 

 chloride solution and allow to stand till clear. 



Phenolphthalein Solution. Dissolve 5 grammes 

 of phenolphthalein in 600 c.c. of alcohol and dilute 

 to i litre with water. Methylated spirit may be used, 

 and if necessary the solution should be heated with 

 animal charcoal, and filtered till clear. 



Silver Nitrate, . Dissolve 17.000 grammes of 



silver nitrate in i litre of water. 



Soda Solution, 50 per cent. Dissolve 250 grammes 

 of caustic soda (purified by alcohol) in 250 c.c. of water ; 

 allow to stand till clear, and store in the apparatus 

 described on p. 68. 



For Kjeldahl Process. Dissolve 300 grammes of 

 caustic soda in water and make up to i litre. After 

 standing a few days, filter through glass wool. 



