47B Miscellaneous Intelligence. 



20. Preparation of pure Oxide of Zinc, by M. Hermann. — It is 

 by no means easy to obtain this substance perfectly pure ; the fol- 

 lowing is M. Hermann's process : Oxide of zinc, or metallic zinc, is 

 to be dissolved in excess of sulphuric acid, and the solution being* 

 filtered, sulphuretted hydrogen is to be passed through, so long 

 as a brown or yellow precipitate is formed. Cadmium, lead, or 

 copper, being thus separated, and the solution filtered, it is to be 

 treated with solution of the chloride of lime, (bleaching powder,) 

 by which the iron and manganese will be separated. The solution, 

 again filtered, is then to be crystallized in porcelain vessels, by 

 which sulphate of lime is rejected, and a mother liquor separated, 

 which usually contains cobalt and nickel. The crystals of sulphate 

 of zinc are to be dissolved in as small a quantity of cold water as 

 possible, and the sulphate of lime filtered out ; then the solution, 

 being rendered more dilute, is to be decomposed by carbonate of 

 soda in slight excess, and the precipitate well washed, dried, and 

 heated to redness : it is then a perfectly pure and beautifully white 

 oxide. — Bull. Univ. A. viii. 263. 



21. Deuto-Sulphuret of Cobalt. — Mix finely divided oxide of 

 cobalt with three times its weight of sulphur, and heat to very dull 

 redness, until no more sulphur sublimes. The deuto-sulphuret con- 

 sists of 100 cobalt + 109 sulphur; it is black; is reduced to gray 

 proto-sulphuret by a strong heat. — Sitterberg. 



22. Separation of Bismuth from Mercury by Potassium. — M. 

 Serullas has pointed a striking instance of the separation of bismuth 

 from mercury. He says a twelve hundred thousandth, and even less 

 of bismuth, when dissolved in mercury, may be separated and 

 rendered visible by the addition of a certain quantity of the amal- 

 gam of potassium and a little water. A black powder is observed 

 to rise from the substance of the metal, and is a mixture of bismuth 

 and mercury in a very divided state ; it rises to the surface or ad- 

 heres to the vessels. 



Copper, lead, tin, and silver, are equally separated, but not so 

 promptly, or so evidently to the eye as bismuth ; for they are not 

 associated with divided mercury, at the time of their separation, like 

 the latter : with bismuth a mere atom is rendered visible, and M. 

 Serullas thinks that chemistry does not present a more delicate test 

 than the amalgam of potassium for bismuth in mercury. — Annates 

 de Chimicy xxxiv. 195. 



23. Sulphur et of Arsenic proportionate in Composition to Arsenic 

 Acid. — M. Pfaff acted upon arsenious acid by nitro-muriatic acid, 

 and obtained a pure arsenic acid soluble in water, and deliques- 

 cent in the air. This, dissolved in 40 parts of water, had a cur- 

 rent of sulphuretted hydrogen i)assed through it, which instantly 

 produced a yellow orange precipitate of a pulverulent form, con- 

 tinuing identical in composition, until no further precipitate was 



