mountains or in the open sea. Hence it follows, that the mercury 

 ought to stand somewhat higher when such a wind blows than with 

 the same wind when it meets with no obstruction ; and the more 

 direct it blows upon the coast, and the higher the land is, the higher 

 ought the mercury to rise. On the other hand, when the wind comes 

 from off the hills, this dense air will be displaced ; and thus the air 

 over the coast will resume its natural state with a land wind. 



Capt. Flinders concludes his paper with some general remarks 

 upon the barometer, of which the following seem to be the most 

 material : 



It is not so much the absolute as the relative height of the mer- 

 cury, and its state of rising and falling, that are to be attended to in 

 forming a judgement of the weather. . 



In the open sea, the changes in the weather, and in the strength 

 of the wind, appear to be the causes that chiefly affect the barometer ; 

 but, near the shore, a change in the direction of the wind seems to 

 affect it as much, or more, than either of those causes taken singly. 



On the open sea, also, the mercury seems to stand higher in a 

 steady breeze of several days' continuance, provided it does not blow 

 hard, than when the wind is variable. Perhaps it is on this account, 

 as well as from the direction of the wind, that the mercury stands 

 higher within the tropics than in those parallels where the winds are 

 variable. 



Upon the whole, our author thinks the barometer capable of af- 

 fording so much assistance to the commander of a ship, that no com- 

 mander in a long voyage should be without one. 



Account of a Discovery of native Minium. In a Letter from James 

 Smithson, Esq. F.R.S. to the Right Hon. Sir Joseph Banks, K.B. 

 P.R.S. Read April 24, 1806. [Phil. Trans. 1806,;?. 267.] 



The minium here described by Mr. Smithson was found dissemi- 

 nated in a compact carbonate of zinc. Its general appearance was 

 pulverulent ; but when a lens was used, it showed, in some places, a 

 flaky and crystalline texture. Its colour was the same as that of 

 factitious minium : when gently heated by the blowpipe it became 

 more obscure, but returned, upon cooling, to its original colour. By 

 a stronger heat it melted into litharge ; and, upon charcoal, was re- 

 duced to lead. 



In dilute nitric acid it assumed a coffee-colour ; and on the addition 

 of a little sugar, this brown calx was dissolved, producing a colourless 

 solution. Upon being put into muriatic acid, with a little leaf-gold, 

 the gold was soon entirely dissolved. 



When it was inclosed in a small bottle with muriatic acid, and a 

 small piece of turnsole paper was fixed to the cork, the paper in a short 

 time entirely lost its blue colour, and became white. Even a slip of 

 common blue paper, whose colouring matter is indigo, when placed 

 in the above situation, underwent the same change. 



This native minium, Mr. Smithson says, seems to be produced by 



