ADULTERATION AND DETECTION. 155 



from the distillate. When this has been accomplished 

 some of the potash and permanganate solution is added 

 to the contents of the retort and distilled so as to yield 

 a distillate containing " albuminoid ammonia," the result 

 being as follows in pure teas : 



Free ammonia, 0.28 milligrams. 



Albuminoid ammonia, 0.43 



Total, .0.71 milligrams. 



While the extract from a sample of spurious leaves 

 yielded of 



Free ammonia, . . 0.20 milligrams. 



Albuminoid ammonia, .... 0.295 



Total, O-495 milligrams. 



This experiment is made with the greatest ease, and 

 will also be found valuable by brokers and others inter- 

 ested in tea for testing the strength of the tea-infusion. 



As has already been observed, tea is also remarkably rich 

 in nitrogen, so much so that a determination of nitrogen 

 may be resorted to as a means of identification. With 

 this object it is best to take a sample of tea, first mixing 

 it up well and powder it in a mortar. Of this tea-powder 

 some 0.3 grams should be accurately weighed out. This 

 is then to be mixed with some 50 grams of oxide of 

 copper, which has been first oxidized without the employ- 

 ment of nitric acid, and which shortly before using had 

 been ignited and allowed to cool. A combustion-tube of 

 hard German glass, closed at one end and perfectly clean, 

 is next charged as follows : At the closed end a layer, 

 some three to four inches in length, of a mixture of dry 

 bi-carbonate of soda and fused bi-chromate of potash is 

 placed, the mixture being intended to give out carbonic 

 acid. Next to this compound place two inches of oxide 

 of copper, then the mixture of tea and oxide of copper, 



