464 Siientijic Inte/Iigeiice. [Junk, 



As several thousand persons had left the population district 

 for want of work during the few months which preceded the 

 enumeration, and as some of these persons may be expected to 

 return, the population may be safely stated at 150,000. 



II. Colouring Matter of a Lichen which grows on the Bark of the 

 Jhiicea Anl i-di/aenterica . 



This lichen had an intense yellow colour. It was subjected 

 to a chemical examination by MM. Pelletier and Caventou. 

 Tliey first digested it in sulphuric ether till every thing soluble 

 in tliat principle was taken up. Nothing was dissolved by the 

 ether but a sohd oil, of a greenish-yellow colour, and a mild taste, 

 and possessing the usual characters of the fatty matter of plants. 

 The hchen was now digested in successive portions of hot alco- 

 liol, till that liquid refused to dissolve any thing more. The 

 alcoholic solutions had a very intense colour. The alcohol vyas 

 distilled oft', and there remained a yellowish-red matter, which 

 attracted humidity when exposed to the air. Water being 

 poured upon it dissolved a yellow-colouring matter, and left a 

 brick-red powder, which was destitute of taste and smell, and 

 perfectly insoluble in water. By boiling it repeatedly in water, 

 it was freed from the remains of the soluble colouring matter, 

 which still might remain mixed with it. 



This substance is a powder of a reddish-yellow colour, inso- 

 luble in cold water, and almost equally so in boiling water. It 

 dissolves with facility in alcohol ; but is insoluble in sulphuric 

 ether. When exposed to heat, it gives out the usual products 

 of vegetable bodies with some traces of ammonia, indicating the 

 presence of azote as one of its constituents. When concentrated 

 nitric acid comes in contact with it, it assumes a fine green 

 colour. This colour is removed by the action of water, and by 

 most of the sahfiable bases. It is owing to a combination of the 

 colouring matter of the lichen with nitric acid. 



Sulphuric and nuu-iatic acid f\\cilitate the solution of this 

 colouring matter in water ; but they at the same time alter its 

 nature ; for it is now very soluble, and is not rendered green by 

 the action of nitric acid. This colouring matter is not acted 

 upon by weak alkaline leys ; but the concentrated solutions of 

 the alkalies decompose it. — (Journ. de Pharm. v. 546.) 



III. Curious Effect produced by kneading po2cdered Guaiacum 

 and good Wheat Flour. 



M. Taddey observed that when the powder of guaiacum and 

 good wheat flour are kneaded together with the requisite quan- 

 tity of water in contact with atmospherical air, the mixture 

 assumed a fine blue colour. M. Rudolphi, whom he employed 

 to examine the action of these bodies on each other, made the 

 following observations : 1 ,when the powder of guaiacum and pure 

 stock are kneaded together, no blue colour is developed ; 2, the 

 powder of guaiacum scarcely becomes blue when kneaded with 



