312 Intelligence aiid Miscellaneous Articles. 



ciple as this Planetarium, but I have not yet attempted to make a 

 ball revolve in such a course; to effect this object a much more 

 complicated apparatus appears necessary than for a circular mo- 

 tion. B. M. FORSTER. 



Walthamstow, Essex, March 12, 1827. 



CRYSTALLIZED LITHARGE. 



M. Gaultier de Claubry remarked that crystals of litharge were 

 formed during the cupellation of argentiferous lead : he collected 

 and analysed some of them. These crystals had the appearance of 

 regular dodecahedrons ; but M. Beudant, who examined them with 

 the assistance of the reflective goniometer, found that they possessed 

 no regular angles, and that their facets were curvilinear. 



M. Houton-Labilliadere had previously obtained litharge in 

 crystals, which appeared to him to be regular dodecahedrons ; they 

 were formed in a solution of oxide of lead in soda, during the win- 

 ter. — [Ann.de Chim. et de Phys. t. vii. p. 218.) 



The cr^'stals obtained during cupellation consisted of: 



Protoxide of lead, with a trace of copper 963 



Carbonic acid S3 



99-6 

 On the surface of the crystals there were semitransparent laminae 

 of a yellow colour, of the size of the nail ; their composition was 

 similar to that of the crystals. — [Ann. de Chim. et de Phys. t. xxiii. 

 p. 4+3.) 



COMPOSITION OF NITRIC ACID. 



The 12th volume of the Annals of Philosophy, O. S. (p. 351), 

 contains a translation of a paper on the composition of nitric acid, 

 by Berthollet : the process employed was that of decomposing ni- 

 trate of potash by heat in a porcelain retort, the weight and nature of 

 the gaseous products and of the residual potash being ascertained. 

 From these experiments the author concluded that nitric acid is 

 composed of 69*6 oxygen + 30'4 azote, instead of 74'08 of the 

 former and 25'92 of the latter element, as now generally admitted. 



Dr. Thomson observes, that though he has no doubt of the inac- 

 curacy of Berthollet's analysis, he cannot pretend to account for the 

 fallacy. Having lately prepared some oxygen gas by decomposing 

 nitre, I found that the last gaseous product, if not entirely azotic 

 gas, contained so little oxygen that it extinguished a candle. Upon 

 pouring water into the gun barrel to remove the potash, I found 

 that oxygen gas was immediately evolved, and in such quantit)' 

 that an ignited stick was immediately inflamed j and the combustion 

 continued tor a considerable period. 



ISlow Berthollet distinctly, though erroneously, asserts, that the 

 potash retains no oxygen: but it is evident from the experiment now 



stated, 



