SCIENTIFIC NEWS* 141 



3. *f The Society demands a theory, or phyfical explication, — the afcentof 

 which fhall clearly and diftin&ly (how the caufes of the afcent fmoke. 

 of fmoke in chimnies, or thofe which prevent its rifing. To- 

 gether with rules, deduced from this theory, for the conftruc- 

 tion of chimnies, which fhall point out the circumftances ne- 

 celfary to be attended to in the feveral cafes to prevent fmoke 

 from entering the apartments ?" 



This queftion is here again repeated, and the anfvver is de- 

 manded before the 1ft of November, 1803, in order that the 

 authors of memoirs may be enabled to correct them. 



4>. " What indigenous plants, hitherto not ufed, may, from — dying plants. 

 well confirmed experiments, afford good colours, which may 

 be prepared and ufed with profit? And what exotic plants 

 may be cultivated with profit upon the lefs fertile or unculti- 

 vated lands of the Republic, in order to the extraction of 

 colours I" 



The Society has determined to repeat this queftion, which 

 is continued without limit of time. • 



The queftions for the prefent year are the following : 



5. "What do we learn, from the lateft obfervations, re effe&ofox- 



fpecting the influence of the oxigen of the atmofphere, whe- lgen on C0 ' 0U1 *« 

 ther combined or not, together with the action of light upon 



the changes of colour ? And what advantages may be derived 

 from this knowledge?" 



The Society defires that it may be fhown concifely, and 

 with precifion, what is welt proved by obfervations or experi- 

 ments, in order that the actual ftateof the fcience with regard 

 to this fubject may be more readily apprehended, and greater 

 advantages obtained in trade, or in the other branches of 

 economy. 



The term of concurrence is November 1, 1803. < 



6. " What light has been thrown upon the manner in which — nourishment 

 plants acquire their nouriftiment, in confequence of the difco- of P lanCs * 

 veries reflecting the decompofition of water and atmofpheric 



air ? And what deductions can be made from this knowledge 

 for the improvement of ufeful vegetables }*' 



The term of concurrence is November 1, 1803. 



7. " What facts are well proved with regard to the purifica- 

 tion of corrupted water, and other impure fubftances, by char- 

 coal ? How far is it poffible to explain this effect by the prin- 

 ciples of chemiftry ? And what further advantages may be 

 thence derived?" 



2 The 



