THE CLARIFICATION OF FRUIT JUICES. 13 



of wax varying between 5 and 50 per cent by weight, 3 the relation 

 of certain commercially employed upper Miocene deposits of diato- 

 maceous earth to oil fields (1, #), and the character of the flavor im- 

 parted to juices indicated that the material might be a derivative 

 of wax. This assumption was borne out by its behavior, but no 

 attempt to isolate the material in quantity or to study it chemically 

 was made. Attention was directed to the working out of simple 

 methods for removing it with sufficient completeness to make the 

 earth free from discoverable effect upon the flavor of the juices. 



PURIFICATION OF THE EARTH. 



Extraction of the earth with the usual fat solvents completely re- 

 moved the material which gives foreign flavor to juices, but such 

 treatment on other than an experimental scale is impracticable. At- 

 tempts to wash out the contaminating material in the manner recom- 

 mended by some filter-press manufacturers, by stirring the earth 

 into boiling water, decanting after settling, and repeating the process 

 a few times, proved ineffective, as earth so treated still had percep- 

 tible effect upon the flavor of delicate juices after 10 or 12 changes 

 of water. Earth boiled on a water bath for several days with re- 

 peated changes of water was not wholly freed of the contaminating 

 material. 



The most satisfactory method of purifying the earth was by in- 

 cineration. In preliminary work small lots were placed in porcelain 

 dishes, heated to low redness for 30 minutes in an electric furnace, 

 allowed to cool, and rubbed through a sieve having 50 to 80 meshes 

 per inch. For the preparation of larger lots a metal container made 

 by capping one end of a 4-inch iron pipe 20 inches long and provid- 

 ing a loosely fitting plug for the opposite end was used. This was 

 filled with the earth, plugged, placed in the fire box of a steam boiler, 

 and allowed to remain for an hour. An ordinary heavy-walled steel 

 kettle provided with a lid has also been used with satisfactory results. 

 The traces of iron thus added to the earth are without discoverable 

 effect upon the juices. 



Purification by heating has the obvious advantage that it permits 

 repeated use of the earth. On burning a quantity of earth which 

 has become loaded with material derived from the juice an insignifi- 

 cant amount of ash remains in the earth, but this does not materially 

 increase with repeated use. Carbon progressively accumulates with 

 repeated burnings, ultimately becoming sufficient to exert an appre- 

 ciable decolorizing effect upon juices filtered through it. In prac- 

 tice it has been found possible to use a single lot of earth 10 to 15 

 times, revivifying by burning after each use, before the carbon 



3 Mann, Albert. Personal communication to tlie writer. 



