Intelligence and Miscellaneous Articles. 153 



If, according to the ordinary hypotheses of perfect elasticity, we 



put a=y and neglect terms depending on |3, /3 f , £, £', this equation 



to the elastic curve coincides with that given by Poisson and others. 



If we put x=a, the value of the deflection at the centre of the 



beam is 



KG* _ bxW (2b°— c)h 3 « 5 

 T 4 5 ' 



Whence it may be seen that the deflection is greater than it would 

 be if the elasticity were perfect. 



XVII. Intelligence and Miscellaneous Articles. 



CHEMICAL EXAMINATION OF A MINERAL CONTAINING OXIDE 

 OF URANIUM, FROM THE NORTH SHORE OF LAKE SUPERIOR. 

 BY J. D. WHITNEY. 



THE specimen of which the analysis follows, was given me by 

 J. W.Foster, Esq., and is the same mineral which has been named 

 Coracite by Mr. J. L. Le Conte, and partially described by him in 

 the American Journal of Science (New Series, vol. iii. p. 174). As 

 it is evident that the conclusions drawn by Mr. Le Conte from his 

 qualitative examination were quite incorrect, and as the mineral 

 differs considerably, in its reaction with acids, from pitchblende, 

 with which it has the greatest analogy, and which at first sight it 

 would seem to be, I have carefully examined it, with the following 

 results : — 



Substance amorphous ; fracture uneven ; without traces of clea- 

 vage ; hardness 3 ; spec. grav. — ; colour pitch-black ; powder 

 gray ; lustre resinous. 



Before the blowpipe it does not change its appearance, or fuse, or 

 colour the flame. It gives with the fluxes the characteristic reac- 

 tions of uranium. 



It dissolves readily without the application of heat in dilute hydro- 

 chloric acid, effervescing strongly ; in which respect it differs en- 

 tirely from pitchblende, which is insoluble, except in nitric acid or 

 in aqua regia. It gives a beautiful green solution, a small quantity 

 of flocky silica separating. 



The analysis was conducted as follows : — 



A portion of the mineral, carefully selected and freed from foreign 

 matters, was pulverized and dried at 100° C. It was then dissolved 

 by hydrochloric acid in a suitable apparatus, the loss of weight being 

 considered as carbonic acid. The silica separated by filtration was 

 found to be pure when tested by the blowpipe, and was entirely 

 soluble in carbonate of soda. In the solution filtered from the silica, 

 sulphuretted hydrogen threw down a precipitate, at first dark brown 

 and afterwards black, of sulphuret of lead, which was estimated as 

 sulphate of lead by oxidizing with nitric acid. The filtered solution 

 was then digested till it no longer smelt of sulphuretted hydrogen, 

 and oxides of uranium and iron and alumina precipitated by caustic 

 ammonia. The precipitate was washed with water to which chlo- 

 ride of ammonium had been added, and then taken moist from the 



