Chap. 28,] Menacbanitt and Uramte. . 157 



A fubftance of a peculiar nature was difcovered by 

 Mr. M'Gregor in the valley of Menachan in Cornwall, 

 which has been therefore called MENACHANITE, and is 

 confidered as a femi- metal. It is found in the form of 

 fmall black grains refembling gunpowder, of no deter- 

 minate ftiape, and often mixed with a grey fand of 

 great fubtilty. Its fpecific gravity when in grains 

 is 4,427 ; in a high heat it flightly agglutinates and 

 acquires a fmall increafe of weight. When in grains 

 it is eafily pulverized, and is pofiefled of fome magnetic 

 power. It is infoluble in acids except by particular ma- 

 nagement i but is then found to confift of about equal 

 proportions of iron, and a peculiar white calx with a little 

 filex. The folution of menachanitic calx in vitriolic 

 acid, is precipitated deep green by Pruflian alkali, 

 white by common alkali, and becomes orange coloured, 

 with tincture of galls. With feveral other folvents it 

 exhibits properties fo peculiar, as to entitle it to be 

 confidered as a new fubftance. 



URANITE was firft difcovered by Klaproth, who 

 found it to polfrfb the following properties. Its colour is 

 dark fleel or iron grey, internally fomewhat browner. 

 Its fpecific gravity 6,440. It is rather more difficultly 

 fufible than manganefe, and has as yet only been pro- 

 duced in fmall globules imperfectly agglutinated. It is 

 foluble in nitrous cid ; but it does not appear that other 

 acids have been tried. Its calx is yellow and manifefts 

 the following properties. It is eafily foluble in acids ; 

 with the dilute vitriolic acid it affords yellow cryftals. 

 With the concentrated acetous acid it affords yellow 

 quadrangular cryftals. It is alfo foluble in many other 

 acids, the products of which folutions vary confiderably 

 both in colour and form. Uranitic calx is infoluble 

 in alkalis, either in the moift or dry way, which fully 

 , diftinguifhes 



