166 



FOODS AND FOOD ADULTERANTS. 



great accuracy. On stopping the extraction the extract is washed into 

 a light weighed glass dish, and the ether allowed to evaporate sponta- 

 neously and not too rapidly, as in the latter case water is condensed in 

 the dish, which it is difficult to remove. When the ether has disap- 

 peared which ought not to take too long, as in that case some oil is vol- 

 atilized the dish is placed in a large dessicator, with pumice and sul- 

 phuric acid chloride of calcium having been shown to be useless* and 

 allowed to remain overnight, to remove any moisture. The loss of oil 

 by this process is hardly appreciable. The dish is then weighed, and 

 afterwards heated to 110 0. for some hours, to drive off the volatile 

 oil, beginning at a rather low temperature, as the oil is easily oxidized, 

 and then is not volatile. The residue is weighed, the difference being 

 calculated to volatile oil, and then examined as to its composition of 

 purity. The results are fairly satisfactory, as appears from the follow- 

 ing duplicates : 



Duplicate fat and volatile oil determinations in spices. 



Alcohol extract. This may be made in the same manner as the ether 

 extract, using, of course, the substance already extracted. The solvent 

 may be either absolute alcohol, that of 95 per cent, by volume, or 80 

 per cent, by weight. The latter is preferable in most cases, as there is 

 no definite point with the stronger spirit at which the extraction is 

 complete. 



In the investigation of spices merely for adulteration this extraction 

 is of little value. 



Starch, &c., reducing sugars. The amount of reducing material pro- 

 duced by boiling the spices with dilute acid serves with several as an 

 index of purity. In the case of pepper, which contains naturally a large 

 amount of starch, the addition of the common fibrous adulterants re- 

 duces the equivalent of reducing sugars which are indicated by Fehl- 

 ing's solution after boiling with acid. Lenz and several others have 

 examined the value of this determination. The conclusions which are 

 deducible from their experience and our own are that with attention to 

 proper condition to insure complete conversion to dextrose the results 

 are of value, though apt to fall out too low. It has been found desirable 

 in our laboratory to run as a check a parallel determination on a sub- 

 stance of known reduction equivalent. In this way any variation may 

 be detected. 



Fleischer, E., 1884, Zeit. Anal. Chem., 23, 33. 



