62 COMPOSITION OF AMERICAN WINES. 



of abrastol this method gives a colorless or light-yellow liquid, while 

 a red color is produced in the presence of 0.01 gram of abrastol. l 



DETECTION OF HYDROXAPHTHOL. 



About 100 cc are acidified with sulphuric acid and subjected to dis- 

 tillation. The first 25 cc of the distillate are made very faintly alka- 

 line with dilute ammonia and then very slightly acid with dilute nitric 

 acid. A drop of a concentrated solution of sodium nitrite is then 

 added. In the presence of hydronaphthol a rose color is developed. 

 The test is a delicate one and is quite characteristic, but requires exact 

 .conditions to be successfully performed. 2 



ESTIMATION OF BORIC ACID. 



Boric acid is a normal constituent of wine and its qualitative detec- 

 tion in wine is therefore of little value. The following method 3 is 

 found to give satisfactory results in the absence of iron: 



One hundred cc of the sample under examination are evaporated to 

 dryness, after being made alkaline with a solution of barium Irydroxid, 

 and the residue is ignited until a white ash is secured. The ash is dis- 

 solved in dilute hydrochloric acid, with the aid of heat if necessary, 

 sodium hydroxid is added, the mixture heated to boiling, and the 

 resulting precipitate separated by nitration and washed with hot water. 

 Throughout the determination care is taken to keep the volume of 

 liquid as low as possible. The filtrate is then acidified with sulphuric 

 acid and brought to the boiling point, to completely expel the carbon 

 dioxide. About two volumes of glycerol are then added and the solu- 

 tion exactly neutralized with sodium hydroxid, using metlryl orange 

 as indicator. The boric acid is now in the free state and may be 

 titrated directly. Phenol phthalein is then introduced, and decinormal 

 sodium hydroxid again added till the liquid becomes red. 



The number of cubic centimeters of decinormal sodium hydroxid 

 required to neutralize the solution to phenol phthalein multiplied by 

 0.0062 gives the grams of H 3 BO 3 per 100 cc of the wine. 



The following method, if carefully followed, gives approximate 

 results, and may be used in a preliminary examination: 



A series of solutions of boric acid in dilute hydrochloric acid (about 

 1 part concentrated acid to 15 parts water), ranging from 1 to 20 mil- 

 ligrams per 100 cc, is prepared. A drop of each solution is placed 

 on a piece of turmeric paper 2 cm square, the paper dried, and the 

 color noted. The pipettes, or pieces of glass tubing used for dropping 

 the solutions, should have apertures of uniform size, in order that as 

 nearly as possible the same amount of solution may be used in each 



, Mon. Sci. [4], 9, 191. 

 2 Beebe, Analyst, 1888, 13, 52. 

 3 K. T. Thomson, Jour. Soc. Chem. Ind., 12, 432. 



