246 SCIENCE IN SHORT CHAPTERS. 



This being the case, and a commercial demand for black tea having 

 become established, the tea-grower would naturally seek to improve 

 the color of his tea, especially of those samples naturally poor in 

 iron, and a ready mode of doing this is offered by stirring in among 

 the leaves while drying a small additional dose of oxide of iron, if he 

 can find an oxide in such a form that it will spread over the surface 

 of the leaf as a thin film. Now, it happens that the Chinaman has 

 lying under his feet an abundance of material admirably adapted for 

 this purpose viz. red hematite, some varieties of which are as soft 

 and unctuous as graphite and will spread over his tea-leaves exactly 

 in the manner required. The micaceous and silicious particles 

 found by Mr. Bird are just what should be found in addition to oxide 

 of iron, if such hematite were used. 



The film of oxide thus easily applied, and subjected to the action 

 of exuding and decomposing extractive matter of the heated leaves, 

 would form the desired black dye or " facing." 



The knotty question of whether this is or is not an adulteration is 

 one that I leave to lawyers to decide, or for those debating societies 

 that discuss such interesting questions as whether an umbrella is an 

 article of dress. If it is an adulteration, and, as already admitted, is 

 not at all injurious to health, then all other operations of dyeing are 

 also adulterations ; for the other dyers, like the Chinaman, add cer- 

 tain impurities to their goods the silk, wool, or cotton in order to 

 alter their natural appearance, and to give them the false facing 

 which their customers demand, but with this difference, if I am right 

 in the above explanation : that in darkening tea nothing more is 

 done but to increase the proportion of one of its natural ingredients, 

 and to intensify its natural color ; while in the dyeing of silk, cotton, 

 or wool, ingredients are added which are quite foreign and unnatural, 

 and the natural color of the substance is altogether falsified. 



The above appeared in iheChemical News, November 21st, 1873, when 

 the adulteration in question was generally believed to be commonly 

 perpetrated, and many unfortunate shopkeepers had been and were 

 still being summoned to appear at Petty Sessions, etc., and publicly 

 branded as fraudulent adulterators on the evidence of the newly 

 fledged public analysts, who confidently asserted that they found 

 such filings mixed with the tea. Some discussion followed in subse- 

 quent numbers of the Chemical News ; but it only brought out the 

 fact that " finely divided iron'' exists in considerable quantities in 

 Sheffield may be " begged, " as Mr. Alfred H. Allen (an able analytical 

 chemist, resident in Sheffield) said. The fact that such finely divid- 

 ed iron is thus without commercial value still further confirms my 

 conclusion that it is not used for the adulteration of tea. If it were, 

 its collection would be a regular business, and truck-loads would be 

 transmitted from Sheffield to London, the great centre of tea-impor- 

 tation. No evidence of any commercial transactions in iron filings 

 or iron dust for such purposes came forward in reply to my chal- 

 lenge. The practical result of the controversy is that iron filings 

 are no longer to be found in the analytical reports of the adulteration 

 of tea. 



