REAGENTS. 221 



OBERMAYER'S REAGENT FOR INDICAN contains 2 to 4 

 grammes of ferric chlorid in a liter of concentrated hydro- 

 chloric acid. 



MILLON'S EEAGENT. Dissolve 1 part of mercury in 

 2 parts of nitric acid (sp. gr., 1.42), first at ordinary tem- 

 perature, then with the aid of heat. When it has dis- 

 solved add twice its volume of water, and after several 

 hours decant the reagent from any sediment that may be 

 present. 



HAMMERSTEN'S REAGENT FOR BILE PIGMENTS consists 

 of 1 volume of nitric acid and 19 volumes of hydrochloric 

 acid, each 25 per cent. When it has become yellow by 

 standing, dilute with four times its volume of alcohol. 



BARFOED'S REAGENT contains acetic acid and cupric 

 acetate of such a strength that there shall be about 1 per 

 cent, of each when mixed with the sugar solution to be 

 tested. 



GUNZBURG'S EEAGENT FOR HC1. Dissolve 2 grammes 

 of phloroglucin and 1 gramme of vanillin in 100 cubic 

 centimeters of alcohol. 



BOAS'S EEAGENT FOR HC1. Dissolve 5 grammes of 

 resorcin and 3 grammes of cane-sugar in 100 cubic centi- 

 meters of dilute alcohol. 



Methyl-violet ^ 



A solution in water containing about 1 

 Trorjseolin 00 



per cent, of the coloring matter. 

 Alizarin sodium 



sulphonate t 



Phenolphthalein, a 1-per-cent. alcoholic solution. 

 Dimethyl-amido-azobenzene, a 0.5 per cent, alcoholic 

 solution. 



