150 ADULTERATION AND DETECTION. 



filter, drying, igniting and weighing it. The weight of 

 the insoluble part of the ash may then be subtracted from 

 the original quantity, in which manner the percentage of 

 soluble and insoluble ash is obtained. 



Peligot has also pointed out that tea-leaves differ from 

 the leaves of other plants by their extraordinary richness 

 in nitrogen, the percentage averaging 4.37 percent, in the 

 raw leaf of the former, and ranging from 5.10 to 6.60 per 

 cent, in the dried state. In the preparation of the fresh 

 leaves for market a quantity of juice is expressed from 

 them, the increase of nitrogen in the prepared leaf being 

 accounted for on the supposition that this juice is not as 

 rich in nitrogen as that still remaining in the leaf, and if 

 the prepared leaf be unique in containing this high per- 

 centage of nitrogen, it is obvious that a determination of 

 nitrogen in tea may prove useful as a method of identi- 

 fication. 



IRON AND STEEL FILINGS IN TEA 



Are best detected by pulverizing a sample of the suspected 

 tea and spreading the powder on a piece of glass or plate, 

 and applying a magnet to the dust. If a quantity of the 

 particles gravitate and adhere to it, the tea is undoubtedly 

 adulterated in this form. While fabrications and sophis- 

 tications in general may be best exposed by treating an 

 infusion of the leaves with a watery solution of sulphur- 

 etted hydrogen or a weak solution of ammonia. Under 

 the first treatment the liquor of pure teas will retain its 

 natural color, but will assume a light-blue tint under the 

 latter. 



Another simpler method for those who may not 

 have the chemicals or appliances convenient is to place 

 a small quantity of tea-leaves in a wine-glass or goblet, 

 pour on cold water, and stir or shake well for a few 

 minutes. The tea, if pure, will only slightly color the 



