828 FOODS AND FOOD ADULTERANTS. 



alkaline reaction. According to my own trials a turbidity always ensues in the be- 

 ginning, but there is no precipitate. On longer heating the cloudiness disappears, 

 and the fluid again becomes clear. Whether the fluid becomes acid or remains alka- 

 line naturally depends on the amount of stearic acid present and the strength of the 

 limewater. 



Fehling * says : As pure wax contains cerotic acid, a body which conducts itself 

 toward alkali, limewater, alcohol, and other reagents recommended for the detec- 

 tion of stearic acid, very much as does the latter, it is not possible to detect admix- 

 tures of less than 10 per cent stearic acid by the known methods. Stearic acid is, 

 however, separated from its solution in cold alcohol on the addition of water, while 

 cerotic acid, though it dissolves in hot alcohol, separates almost completely on cooling 

 and the solution then contains so little that it is not much affected by the addition 

 of water. Fehliug therefore boils the wax for four or five minutes with twenty 

 times its weight of alcohol, allows to stand for several hours in order to completely 

 cool, filters and adds water to the filtrate. If the wax be pure the liquid is only 

 slightly clouded, but in presence of stearic acid a flocky precipitate falls. One per 

 cent of stearic acid gives a strong, unmistakable turbidity. In detail the method is: 

 Boil 1 gram wax in a test tnbe with 10 cc. of 80 per cent alcohol for several minutes 

 and then allow to cool to about 18 or 20. Filter into a cylinder, add water, and 

 shake. The stearic acid separates in flocks on the surface and the underlying fluid 

 becomes nearly clear. 



DETECTION OF TALLOW OR ANIMAL FAT IN BEESWAX. 



Grease t can be detected by scraping a smooth surface on a cake of wax and at- 

 tempting to write on it with pen and ink, which can be readily done should the wax 

 be pure. Another plan is to scratch the wax with the finger nail. If pure the wax 

 will show a shining line along the scratch, but if tallow is present the line will be 

 dull. A fresh break will generally show the presence of tallow, if present, by the 

 smell. 



Hagert shakes 1 to 1.5 grams of the chloroform solution of the wax with 12 to 15 

 grams of limewater. In the presence of stearic acid a mealy lime soap forms, as- 

 suming dendritic shapes, while the solution of pure wax in chloroform separates in 

 the form of a white emulsion. Even in this modification the method of Regnard can 

 not be recommended. 



Benedikt proposes to boil the wax sample with carbonate of soda and allow to 

 cool. In the presence of stearic acid the solution solidifies from the formation of 

 otearate of soda. This method is good, but is not so certain in presence of small 

 quantities as that of Fehliug. 



DETECTION OF PARAFFIN AND CERESIN. 



Wagner)] detects the presence of paraffin and estimates its quantity by the influ- 

 ence it exercises on the specific gravity of the wax. He says : Normal wax has a 

 constant specific gravity, and paraffins of very different origin show specific gravi- 



"Dingl. polyt. Jour., 1858, 147, 227. 



t Amer. Bee Jour., 21, 19, 298. 



t Comment., Pharm. Germ., 1873, 436. 



\S Analyse der Fette, 291. 



|| Dingl. polyt. Jour., 1867. 185, 72. 



