This experiment is made with the greatest ease, and will also be found valuable by brokers and others interested 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 employment 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, then more oxide of copper and some clean metallic copper on top, then a perforated cork and exit tube, which dips under the mercury, and place the combustion-tube in an appropriate furnace to heat. By heating the layer of carbonate of soda and bi-chromate of potash, carbonic acid is caused to traverse the tube and expel the air from it. This having been done the tube is next heated gradually from before so as to burn up the tea, the gases being collected over the mercury. At the end of the operation the carbonic acid is once more made to traverse the tube by again heating the mixture at the back, all the nitrogen being driven from the tube and collected. Finally the carbonic acid is absorbed by means of the potash and, the residual nitrogen gas is measured with well-known precautions. This gas should also be tested for bin-oxide of nitrogen by means of oxygen and pyro-galate of potash, any bin-oxide of nitrogen gas to be measured and allowed for in the test. Among the most common forms of adulteration practiced by dealers in this country is that of substituting old and valueless Young Hysons for Japans or mixing them together the better to disguise the fraud. The mixing or blending of old, stale, weedy or smoky Congous with Oolongs, particularly when such teas become a drug on the market. The reduction of Moyunes by the addition of Pingsueys in the proportions of half and half and then refacing them as “True Moyunes.” The refacing of Ningyongs and other Amoys as Formosas being still another form, for which at the present low prices of the commodity there is not the slightest occasion. The most recent “trick” of the tea trade being that of mixing Japan Nibs with Twankays and Hysons, the latter, I regret to add, being now extensively adopted by at one time reputable houses.