510 Mr. Warington on the Green Teas of Commerce. 



ing the leaf, and without apparent loss of any of its charac- 

 teristic qualities. When the drying was complete the sample 

 appeared nearly as dark as the ordinary black teas, and when 

 examined by the microscope presented a smooth surface, per- 

 fectly free from the previously observed facing, and having 

 all the characters of black tea, with the exception of the corru- 

 gated aspect which is common to the greater part of the teas of 

 the latter variety, and which evidently arises from their having 

 been exposed in the operation of drying to a much higher 

 temperature. The greenish-coloured turbid liquid which 

 passed through the meshes of the muslin filter was allowed 

 to deposit the matter suspended in it, which was then washed 

 and collected. These sediments, obtained from various sam- 

 ples, were submitted to the following course of chemical ex- 

 amination. They were, in the first instance, tested with a 

 solution of chlorine gas in water, to ascertain if the colouring 

 material was indigo or other vegetable colour; this substance, 

 as we shall presently see, having been supposed by some 

 persons to be the one employed by the Chinese for the purpose 

 of imparting the blue tint to some of their green teas. In 

 no case, however, that I have yet examined have I found 

 this to be the case ; but the colouring agent has invariably 

 proved to be the ferrocyanide of iron or Prussian blue. The 

 presence of this compound was next evidenced by adding a 

 small drop of caustic potash to a little of the sediment under 

 examination, when the green hue was instantly converted to 

 a bright reddish brown, the original blue appearance being 

 again restored by the subsequent addition of a little diluted 

 sulphuric acid. The other ingredients of the facing were 

 sought for in the manner stated in the previous part of this 

 paper, and also by heating a part of the sediment, after cal- 

 cination and free exposure to the air, with carbonate of soda, 

 to fusion, which, in the case of sulphate of lime being present, 

 formed sulphate of soda and carbonate of lime, and these were 

 each subsequently tested for. 



By these means Nos. 5, 8, 10 and 1 1 were found to be faced 

 with Prussian blue and sulphate of lime. Nos. 6 and 7 gave 

 no indication of Prussian blue, but of sulphate of lime only. 

 The sulphate of lime from some samples appeared to be cry- 

 stallized gypsum reduced to a fine powder, the coarser parti- 

 cles still exhibiting a crystalline structure. 



Through the kindness of Mr. Greene, of the East India 

 House, I was enabled to obtain samples of the Assam teas in 

 a genuine condition ; No. 12. Imperial, No. 13. Gunpowder, 

 and No. 14. Hyson. They had none of the blue granules, 

 were very filamentous, and presented the same appearance as 



