88 MICHIGAN ACADEMY OF SCIENCE. 



THE DETECTION OF BORAX AND BORIC ACID IN MILK. 



(lu abstract.) 

 BY AY. H. YEEXBOER. 



There is still some diYersity of opinion and some contradiction of 

 statement concerning the injurious effects on man of borax or boric acid 

 when used as a preserYatiYe in his food. HoweYer, it is not the purpose 

 of this paper to enter into this discussion, but to state briefly some of 

 the tests by means of which borax or boric acid may be detected in 

 milk. 



When turmeric paper is moistened AYith a solution of boric acid and 

 then allowed to dry it takes on a characteristic pink color which changes 

 to a slaty-blue or green when a weak alkali is added. This test may be 

 made by adding tincture of turmeric to boric acid solution and then 

 eYaporating the mixture to dryness, when the residue becomes pink, 

 and changes to blue or green on the addition of dilute alkali. 



The aboYe mentioned test may be applied to milk in a Yariety of ways. 

 One of the simplest methods of procedure consists in placing one drop 

 of the milk, after it has been well shaken, in a porcelain dish, then 

 adding two drops of a saturated tincture of turmeric and an equal quan- 

 tity of strong hydrochloric acid, and drying on the water-bath. To the 

 residue thus obtained, as soon as it is cool, one drop of dilute ammonia 

 is added, when a slaty-blue color turning to green indicates borax or 

 boric acid. By means of this test 0.001 gram nmy be detected. A 

 smaller amount giYCS the green but not the blue coloration. The hydro- 

 chloric acid may blacken the residue and mask the test; this can be 

 aYoided by eYaporating the turmeric and milk and adding the acid to 

 the dry residue and then eYaporating to dryness again. When this 

 is done the residue is found to be pink and turns to blue and green on 

 the addition of a drop of ammonia. This test can be Yery rapidly applied 

 to a large number of samples by using a porcelain plate. Drops of milk 

 from the Yarious samples are placed side by side and numbered or 

 marked with a wax pencil ; then the plate is dried and the test completed 

 as aboYe indicated. If the amount of borax or boric acid is not suffi- 

 ciently large to be detected by the procedure just giYcn, 100 c. c. of the 

 milk may be used. In this case, the milk is rendered alkaline by the 

 addition of lime or baryta water, in order to precipitate the phosphates, 

 and is then eYaporate'd to dryness and charred. The residue is dis- 

 solYed in as little concentrated hydrochloric acid as possible and filtered 

 from the insoluble carbon. The filtrate is eYaporated to dryness in order 

 to driYe off the excess of hydrochloric acid and the residue is again 

 dissohed in a small amount of dilute hydrochloric acid, and this again 

 eYaporated. By this application of the test one part of the preserYa- 

 tiYe in a million of the milk may be detected. 



When borax is treated with some strong acid and methyl alcohol 

 added and the mixture ignited, a green flame is obtained. 



