'I HE ALUMNI JOURNAL. 



237 



equal parts of guaiac tincture and turpentine 

 oil. becomes blue owing to the precipitation of 

 guaiac resin. The color is permanent to heat. 

 See also Weber and Schoenbein. 



Almen's tannin solution serves as a precipi- 

 tant for albumen. It consists of a solution of 

 4 grams tannin, 8 ccm, of 25 per cent, acetic 

 acid and 190 ccm. of 40 to 50 per cent, alcohol. 

 It also precipitates nucleoalbumin. 



Almen's reagent for glucose is prepared by 

 digesting 2 grams of basic carbonate of bismuth 

 with 100 ccm. potassa solution, specific gravity 

 1.33, and 4 g. Rochelle salt. Upon cooling 

 the clear solution is decanted from the precipi- 

 tate. I ccm. of the reagent is boiled for several 

 minutes with 10 ccm. of urine. If glucose is 

 present a yellowish brown precipitate results, 

 which becomes darker and finally black. 



This reagent is also known as the Boettger- 

 Almen reagent. Compare also Nylander^ s so- 

 lution. 



Anderson's reaction for distinguishing be- 

 tween chinoline and pyridine salts. The chlo- 

 ro-platinates of the latter, when boiled with 

 water, are converted into insoluble double salts 

 with the elimination of hydrogen chloride, 

 whereas the former remain in solution. 



Arata's test for artificial dyestuflfs in wine de- 

 pends upon the observation that these dyestutfs 

 are abstracted from the wine by means of wool. 

 The fibre is then subjected to special reactions- 



Arndt's determination of sugar by means of 

 the ferment saccharometer. See Einhorn, 



Arnold's reactions for alkaloids. 



I. Some alkaloids when heated on the water 

 bath with syrupy phosphoric acid, obtained by 

 dissolving metaphosphoric acid or phosphoric 

 acid anhydride in ofiScinal phosphoric acid (Ph. 

 G. Ill), produce characteristic color reactions: 

 aconitine — violet; nicotine — yellow; coniine — 

 green. 



II. Triturated with concentrated sulphuric 

 acid, many of the alkaloids yield characteristic 

 color reactions upon the addition of concentrat- 

 ed 30 to 40 per cent, alcoholic (in some in- 

 stances aqueous) potassa solution. 



III. Arnold-VitalV s reaction. A small quan- 

 tity of alkaloid is triturated with concentrated 

 sulphuric acid and a grain of sodium nitrite is 

 added; then as in II. strong potassa solution. A 

 number of alkaloids produce characteristic 

 color reactions. Thus, e. g. atropine and homa- 

 tropine produce with sulphuric acid and sodium 

 nitrate an orange yellow color which upon the 

 addition of the potassa becomes reddish violet 

 and fades to rose red. 



Arnold's reaction for narceine. Upon heat- 

 ing a substance containing narceine with con- 

 centrated sulphuric acid and a trace of phenol 

 a reddish color is produced 



Axenfeld's reagent for albumen is a o. i per 

 cent, solution of chloride of gold. The solu- 

 tion to be tested is acidulated with formic acid 

 and heated with a drop of the reagent. If al- 

 bumen is present, the solution becomes purplish, 

 upon the addition of more gold chloride, blue. 

 The latter color reaction is also produced by 

 glucose, starch, tyrosine, leucine, etc., but pur- 

 plish color is characteristic for albumen. 



Aymonier's reaction for a-naphthol. The 15 

 per cent, alcoholic solution of a-naphthol is 

 colored violet upon the addition of cane sugar 

 and mixing with 2 vol. sulphuric acid. Upon 

 the addition of one drop of a mixture of i per 

 cent, potassium bichromate, 10 per cent, water 

 and I per cent, concentrated nitric acid, the 

 same a-naphthol solution yields a black precip- 

 itate. |i-naphthol does not produce either of 

 these reactions. 



Bach's reagent for hydrogen peroxide, con- 

 sists of the following solutions: 



a) 0.03 potassium bichromate and 5 drops 

 of aniline in i liter of water. 



b) 5 per cent, oxalic acid solution. 



5 ccm. of the solution to be tested, when 

 shaken with 5 ccm. of solution (a) and i drop 

 of solution (b), yields a violet red coloration 

 when hydrogen peroxide is present. 



Barbot's reagent for fatty oils is fuming nitric 

 acid. When mixed with this reagent, different 

 oils show different behavior with regard to col- 

 oration and solidification. Olive oil, for exam- 

 ple, yields a white (not red or brown) mixture 

 which solidifies after i to 2 hours. 



Barfoed's reagent for glucose is either a so- 

 lution of 14 grains crystallized copper acetate in 

 200 ccm. water and 5 ccm. acetic acid, or, ac- 

 cording to a more recent formula, of 0,5 copper 

 acetate in 100 ccm. water and i ccm, acetic acid. 

 Glucose reduces this solution in the cold, more 

 quickly upon heating. Dextrin, cane sugar 

 and milk sugar do not reduce the solution. Ic 

 is used for the distinction between glucose and 

 lactose in urine. 



Barreswil's reagent for glucose corresponds to 

 Fehling's solution, but contains potassa in 

 place of soda. 



Basoletto's reagent. A mixture of equal parts 

 by volume of sesame oil and a 2 per cent, solu- 

 tion of cane sugar in hydrochloric acid, specific 

 gravity 1.124, is colored red in the cold, but 

 more rapidly upon heating. With glucose and 



