1822.] 



Scientific Intelligence. 



\m 



and that the proportion of extractive matter not precipitable by gela- 

 tine is greatest in the latter." 



** Sulphuric^ muriatic, and acetic acids, but especially the first, occa- 

 sion precipitates in infusions both of black and green tea, which have 

 the properties of combinations of those acids with tan. Both infusions 

 also yield, as might be expected, abundant black precipitates, with 

 solutions of iron ; and when mixed with acetate, or more especially 

 with subacetate of lead, a bulky buff-coloured matter is separated, 

 leaving the remaining fluid entirely tasteless and colourless. This 

 precipitate was diffused through water, and decomposed by sulphur- 

 etted hydrogen; it afforded a solution of tan and extract, but not any 

 traces of any peculiar principle to which certain medical effects of tea, 

 especially of green tea, could be attributed." 



Mr, Brande observes, that there is one property of strong infusions 

 of tea, belonging especially to black and green, which seems to 

 announce the presence of a distinct vegetable principle; namely, that 

 they deposit, as they cool, a brown pulverulent precipitate, which 

 passes through ordinary filters, and can only be collected by deposition 

 and decantation ; this precipitate is very slightly soluble in cold water 

 of the temperature of from 50° downwards, but it dissolves with the 

 utmost facility in water of 100° and upwards, forming a pale-brown 

 transparent liquid, which furnished abundant precipitate in solutions 

 of isinglass, of sulphate of iron, of muriate of tin, and of acetate of 

 lead ; whence it may be inferred to consist of tannin, gallic acid, and 

 extractive matter. 



The following table is given by Mr. Brande as showing the respective 

 quantities of soluble matter in water and alcohol, the weight of the 

 precipitate by isinglass, and the proportion of inert woody fibre on 

 green and black tea of various prices : 



One hundred parts of tea. 



Green hyson, \^s, per lb. 



Ditto, 12s 



Ditto, \0s , 



Ditto, 85 



Ditto, Is , 



Black souchong, 12*, . . . 



Ditto, 10.? 



Ditto, Is. , 



Ditto, 6s 



Inert re 

 due. 



56 

 51 

 51 

 58 

 59 

 64 

 6S 

 64 

 Q5 



(Royal Institution Journal,) 



V, Spontaneous Explosion of Odorine and Hydrogen. 

 It has been long known that a mixture of chlorine and hydrogen 

 explodes when exposed to the direct action of the sun's rays. In 

 order to try if this effect could be produced by the radiation of a com- 

 mon culinary fire. Professor Silliman filled a common Florence oil- 

 flask (well cleaned) half full of chlorine gas, and was in the act of 

 introducing the hydrogen in the pneumatic cistern. ** There was not 



