PRESERVATIVES. 4,'* 



Halphen's reagent is prepared as follows: An approximately 1 per 

 cent solution of sulphur is made by dissolving about one third of a 

 teaspoonful of precipitated sulphur in 3 or 4 ounces of carbon bisul- 

 phid. This solution mixed with an equal volume of simyl alcohol 

 forms the reagent required by the method. A smaller quantity than 

 that indicated by these directions may of course be prepared. 



1 f turmeric paper be not available it may be made as follows: Place 

 a bit of turmeric powder (obtainable at any drug store) in alcohol, 

 allow it to stand for a few minutes, stir, allow it to stand again until 

 it settles, dip a strip of filter paper into the solution, and dry it. 



DETERMINATION OF PRESERVATIVES. 



The following methods cover all of the more important commercial 

 preservatives with the exception of sulphites and fluorids. These are 

 quite frequently used for preserving foods the former with meat 

 products and the latter with fruit products but, unfortunately, the 

 methods for their detection are not suitable for household use. 



DETECTION OF SALICYLIC ACID. 



The determination of salicylic acid can best be made with liquids. 

 Solid and semi-solid foods, such as jelly, should be dissolved, when 

 soluble, in sufficient water to make them thinly liquid. Foods con- 

 taining insoluble matter, such as jam, marmalade, and sausage, may 

 be macerated with water and strained through a piece of white cotton 

 cloth. The maceration may be performed by rubbing in a teacup or 

 other convenient vessel with a heavy spoon. 



Salicylic acid is used for preserving fruit products of all kinds, 

 including beverages. It is frequently sold by drug stores as fruit 

 acid. Preserving powders consisting entirely of salicylic acid are 

 often carried from house to house by agents. It may be detected as 

 follows: 



Between 2 and 3 ounces of the liquid obtained from the fruit prod- 

 ucts, as described above, are placed in a narrow bottle holding 5 ounces, 

 about a quarter of a teaspoonful of cream of tartar (or, better, a few 

 drops of sulphuric acid) is added, the mixture shaken for two or three 

 minutes, and filtered into a second small bottle. Three or four table- 

 spoonfuls of chloroform are added to the clear liquid in the second 

 bottle and the liquids mixed by a somewhat vigorous rotary motion, 

 poured into an ordinary glass tumbler, and allowed to stand till the 

 chloroform settles out in the bottom. Shaking is avoided, as it causes 

 an emulsion which is difficult to break up. As much as possible of 

 the chloroform layer (which now contains the salicylic acid) is removed 

 (without any admixture of the aqueous liquid) by means of a medicine 

 dropper and placed in a test tube or small bottle with about an equal 



