Intelligence and Miscellaneous Articles. 155 



of lustre, the surface of the concentric layers being quite dull, while 

 there is only a slight degree of resinous lustre on the fracture. 



The colour of erinite is a beautiful emerald-green, slightly inclining 

 to grass-green •. the streak, likewise green, is a little paler, and ap- 

 proaches to apple-green. It is slightly translucent on the edges. 

 The substance of erinite is brittle; its hardness I found = 45... 5*0 

 of the scale of Mohs j its specific gravity = 4043. 



According to the locality attached to the specimens in Mr. Allan's 

 cabinet, they are natives of the county of Limerick in Ireland. For 

 the name of Erinite, which is here proposed for this mineral, the mi- 

 neralogical public is indebted to Mr. Allan. It unites, what is rarely 

 the case with mineralogical names, the comparatively trite and pro- 

 saical allusion to the native country? with the poetical recollection of 

 the characteristic verdure of the " Emerald Isle." 



Erinite is associated with two of the species containing arsenic acid 

 and copper, described by Count Bournon ; the common arseniate of 

 copper (prismatic olive-malachite of Mohs), and the dark blue arse- 

 niate, both of them crystallized and disposed between the concentric 

 layers of erinite. Dr. Turner gives the following as an approxi- 

 mation of the analysis of erinite : — 



Oxide of copper 59*44 



Alumina 1*77 



Arsenic acid 33*78 



Water 501 



100*00 

 Brewster's Journal, July 1828. 



ALTERATION OF CRYSTALLINE STATE IN SOLIDS. 



M. Mitscherlich finds that when sulphate of magnesia or sulphate 

 of zinc is slowly heated in alcohol, and the heat be gradually increased 

 to boiling, the crystals lose their transparency by degrees ; and when 

 broken they are found to consist of a great number of new crystals 

 entirely different from those of the salt employed, owing to the change 

 in the position of the atoms, by internal motion, without the occur- 

 rence of solution. Ann. de Chim. xxxvi. p. 206. 



DECOMPOSITION OF AMMONIA BY METALS. 



M. Savart found that 141*91 grains of thin copper wire became 

 142*382 grains, or acquired an increase of 0*472 in weight, when 

 used for four hours to decompose ammonia : as the wire was in a 

 slight degree oxidized, the experiment was repeated ; and when every 

 precaution was employed, the increase amounted to -rfr, and 0*105 

 of an unknown substance was absorbed by the copper, and its speci- 

 fic gravity was diminished from 8*8659 to 7*7919. 



Iron also increases in weight, and diminishes in specific gravity by 

 similar treatment, and will strike fire with flint like ordinary steel. 



Ibid, xxxvii. p. 326. 



IODIDES OF CARBON. 



Whilst experimenting for a peculiar purpose, M. Mitscherlich min- 

 gled the alcoholic solutions of iodine and soda. " There was formed 



X 2 imme- 



