152 Miscellaneous Intelligence. 



Chloride of Nickel. — Prepared by evaporating the muriate 

 of nickel to dryness. The dry product is the protochloride of 

 nickel ; is of a yellow-green colour, and is composed of 



Nickel 100 



Chlorine .... 90 

 When the proto-chloride of nickel is calcined in a retort, 

 one portion of an olive-green colour remains in the bottom of 

 the vessel, whilst another sublimes and crystallizes in small 

 light brilliant plates of a gold yellow colour. These are to be 

 considered as a deuto-chloride of nickel, and are insoluble in 

 water, and indecomposable by sulphuric acid. They are 

 formed of 



Nickel . . 100? , ,, . S 100 



Chlorine . 200 < by theory of J ^g^ 



Iodide of Nickel. — Obtained by heating nickel and iodine 

 in a tube. It is a brown substance ; fusible ; soluble in water, 

 colouring it of a light-green ; and composed of 



Nickel . . 100) . ,, ^ flOO 



Iodine . . 320J ^y ^^'^""y ^U312.5 



Anil, de Chim. xxi. 255. 



4. On Indigo, Cerulin, Phenicin, Sfc, by Mr. Crum. — The 

 following is a very compressed account of some points on the 

 chemical history of indigo, for which science is principally in- 

 debted to Mr. Crum. We have taken them from that gentle- 

 man's paper, published in the Annals of Philosophy. 



Indigo may be obtained by agitating the yellow liquid of the 

 dyer's blue vat in contact with air, and digesting the precipitate 

 in dilute muriatic acid, and afterwards in alcohol. To obtain 

 it perfectly pure it should be sublimed, which is best done by 

 placing eight or ten grains of it in the cover of a platinum 

 crucible, putting another cover over it, and then heating the 

 lower by a lamp; a sublimate rises which is pure indigo. The 

 apparatus must not be cooled during the sublimation. Sub- 

 limed indigo crystallizes in long flat needles, splittmg into 

 quadrangular prisms. Looked at in heaps, the colour is rich 

 chestnut-brown ; at a particular angle, they have an intense 

 copper-colour, but thin plates when looked at directly before 

 the light, are seen to be transparent, and of a beautiful blue 

 colour. Indigo sublimes at 550°, and it melts and also de- 

 composes very nearly at the same temperature. Its specific 

 gravity is 1.35. It sublimes in open vessels leaving no residuum. 



