ADDITION OF AXTISEPTK S 63 



milk are mixed with milk of lime, evaporated and 

 ignited; the ash is dissolved in a very little concentrated 

 hydrochloric acid; the carbon is tiltered out, the filtrate 

 is made slight! j' alkaline and evaporated to dryness. 

 This salt is treated with a little turmeric tincture and 

 with some very dilute sulphuric acid and is evaporated 

 in a water bath. Tf boiic acid is present, the mass is 

 colored a distinct cherry red. 



[LelTmann "^ gives the following method: "A few 

 drojts of the sample are mixed with a drop of hydro- 

 chloric acid and a drop of strong alcoholic solution of 

 turmeric, cva])()i'ated to dryness at a gentle heat, and a 

 droji of ammonium hydroxide addcfl to the residue when 

 cold. A dull green stain shows that l)oric acid is pres- 

 ent." 



Richmond " offers this method: " To a little milk add 

 a few drops of i)henoli)htliaIein, and sodium hydroxide 

 solution, dro]i l>y drop, till a faint i)ink color is \n-o- 

 duced; ]ilace some of tlie milk in two test tulies, dilate 

 one with an e(iual volume of water, and the otiu'r with -j 

 iiiutidl T)!) })er cent, solution of glycerin; in the aliseiice 

 of boric acid the two tubes will have almost the same 

 color, in its i)resence the gl>cerin tube will be the 

 lighter, and usually white." L.P.] 



b. Salicylic acid in a quantity e([uivalent to 0.04 per 

 cent, can jirevent the souring of milk for ;!(i hours, e\en 

 when the milk remains at IS^ C. It is very hard to 

 dissolve and has not been extensively used to preserve 

 milk. 



Salicylit- acid has the effect of checking digestion and, 

 with some i)ersons, it may cause irritation of the kid- 

 neys; particularly for children, salicylic acid should be 



"Analy.-i.- "f Milk and ^lilk Products. 

 '■' Labiiratoiv Book of r)aii y Analy-^is. 



