500 SCIENTIFIC RECORD FOR 1S84. 



Compounds of Chromium Sesquichloride with metallic Chlorides, by Abb6 

 Glodefroy. — The author fludsthat the sesquichloride of chromium forms 

 with chlorides of several metals well defined and crystallized combina- 

 tions. The method of preparation is as follows : To obtain a compound 

 of chromium chloride with the chloride of a metal, R, pass a current of 

 chlorine gas iuto a mixture of 700 grams of alcohol aud 300 grams of the 

 chromate (or dichromate) of E, until the liquid fumes freely when ex- 

 posed to the air. If the liquid separates into two layers, add enough 

 alcohol and continue to pass the chlorine. Decant, filter through glass 

 wool with the aid of a filter-ijumi), wash with concentrated HCl, and 

 dry on a i)late of porcelain at a gentle heat. Transfer to dry and well- 

 corked bottles. These double salts are decomposed by water with the 

 formation of HCl. Bromides and iodides of chromium and the metals 

 are obtained in a similar manner. The potassium salt has the formula 

 4 KCl . CraCle + 2 H2O. " {Bull soc. chion., XLii, 194.) 



Recovery of Zinc from the Residues of Pyrites. — At theWocklum Works 

 a process has been in operation for many years by which zinc chloride 

 is recovered from the burnt pyrites. The burnt ore is lixiviated, thus 

 extracting the iron and cupric sulphates ; the lixivium is concentrated 

 to crystallization, is mixed with a quantity of sodium chloride equiva- 

 lent to the zinc sulphate in the solution, and thereby deposits Glauber's 

 salts, the value of which alone covers the whole expense of treatment. 

 The mother liquid is concentrated ; various mixed ferrous and sodium 

 sulphates crystallize out ; the zinc chloride remaining in solution is ob- 

 tained by evaporating to dryness. The dry salt contains, however, 

 about 15 per cent, sodium salts. {Revue scientifique Quesneville.) 



On the Bromides of Tin, by Bohuslaw Rayman, and Karl Preis. — The 

 authors describe the dibromide and tetrabromides of tin, and several 

 compounds of the latter with other metallic bromides. SnBrg forms a 

 crystalline, yellowish, transparent mass, meltiug at 215.5^. to a pale 

 yellow liquid. It forms with water a crystalline hydrate, which appears 

 in colorless needles or thin prismatic crystals, soluble in water with 

 turbidity. SnBr4 distills at 196'^ to 198°, and the distillate solidifies to a 

 ijiass of crystals with a white, mother-of-pearl luster. They rapidly 

 deliquesce on exposure to the air, aud form a hydrate, SnBr4 . 4 H2O. 

 The following compounds are also described : Stannohydrobromic acid 

 and its salts of sodium (Na^SnBre + 6 H2O), of calcium, strontium, mag- 

 nesium, manganese, iron (FeSnBre + 6 H2O), nickel, and cobalt ; also the 

 oxybromide of tin (SnaBrgO + 12 H2O). {Liehiifs Annalen, coxxiii, 323.) 



Permeability of Silver by Oxygen Gas, by L. Troost. — The author shows 

 that pure oxygen and the oxygen of the atmosphere are capable of 

 passing through the sides of a heated tube of silver, while only a trace 

 of nitrogen permeates the metal. Carbon monoxide and dioxide also 

 penetrate the silver, though less rapidly than oxygen. The author 



