22 



The Naturalist. 



prepared with tea alone, with catechu alone, and also with a mixture 

 of the two, were then exhibited. 



(c) A third form of adulteration is the admixture of sand and 

 other mineral matters, such as magnetic oxide of iron. The addition 

 of these substances is easily discovered. A weighed quantity of Tea 

 is burnt in a platinum capsule, and the ash is weighed. The ash of 

 pure Tea amounts to 5*75 °/^, but, making every allowance for 

 accidental admixture of dust, &c., during the preparation of it, 

 the Society of Public Analysts has adopted 8 as the limit of ash 

 for genuine Tea. Any excess above this must be considered as wilful 

 admixture. The ash of re-dried exhausted leaves is less in amount 

 than that of genuine Tea ; we have here, therefore, another indication 

 of this form of sophistication. Exhausted and re-dried leaves give 

 only 3 7o of ^sh. The ash of genuine Tea is more than half of it 

 soluble in water, and almost the whole of it is soluble in weak 

 hydrochloric acid : what remains undissolved is sandy matter, &c. 



The presence of magnetic oxide of iron may readily be ascertained 

 by using a magnet, which attracts that mineral. 



(d) The facing or colouring of Tea. The dusting of Tea with 

 Prussian blue, indigo, sulphate of lime, China clay, and such matters, 

 was supposed to be necessary to please the English consumer. The 

 bright coloured green Teas have all been treated in this way. The 

 Bill now before Parliament will, I think, entirely do away with this 

 form of adulteration, as it expressly prohibits the powdering, 

 colouring, or staining any article of food or drug, with the intention 

 of making it appear what it is not. Under the same Act also. Tea 

 will be examined on its arrival in this country by the Custom House 

 officials, and will not be allowed to pass into commerce, if found 

 adulterated. The Tea sold in the country will, however, still be 

 liable to be examined by the Public Analysts. Verily, good times 

 are coming for those who love the ''cup that cheers but not inebriates." 



Huddersjkld, June, 1875. 



THE PLEASURES OF A MICROSCOPIST. 

 By Thomas Armstrono, F.R.M.S. 



The microscopist, unlike students in many branches of science, can 

 find employment at all times and in all seasons, hence the pleasures of 

 microscopy are summer and winter ones, and are alike enjoyed at 

 home and abroad. The microscopist need never be idle, for, first, in 



