488 Miscellaneous Intelligence, 



When carbonate of soda is added to sulphate of copper in ex- 

 cess, the precipitate obtained is a svhsulphatc of copper -, this salt 

 does not change by ebullition. Sulphate and carbonate of zinc 

 boiled together also produced a subsuli^hate of zinc. — Annales de 

 Chimie, xxxvii. 335. 



20. Discovert) and Separation of Antimony from" Lead, Copper, S^c, 

 — If an alloy, containing tin, but no antimony, be dissolved in ni- 

 tric acid, all dissolves except the tin, which separates as a white 

 oxide ; but if antimony be present, in however small a quantity, 

 the oxide of tin acquires a yellow colour. When tin is precipi- 

 tated by nitric acid, it has the power of taking all the antimony 

 present with it. M. Bussolin, who remarked these facts, has em- 

 ployed them usefully in the distinction and separation of antimony 

 from lead, &c. — Gior. di Fisica. 



21. Singular action of Arsenic, J cid on Sugar.— When a solution 

 of pure arsenic acid is mixed with sugar and left for a few hours, 

 a rose colour is produced which soon becomes a fine purple, and 

 then remains, with little further change, for many days. Sugar 

 of milk, mannite, raisin sugar, sugar of starch, produce similar 

 effects ; but sugar of liquorice, diabetic sugar, and such bodies as 

 starch, gum, &c. produce no effect of the kind. Nor do the so- 

 luble arseniates or arsenious acid produce these effects with the 

 substances named above. — Bull. Univ. A. ix. 281. 



22. Preparation of Chromic Acid, % M.Maus.~A hot and con- 

 centrated solution of the bi-chromate of potash is to be decomposed 

 by fluosilicic acid ; the liquid is to be filtered and evaporated to dry- 

 ness ; the acid thus dried is to be dissolved in as small a quantity 

 of water as possible, and the clear fiuid decanted from the deposit 

 of fluo-silicate of potash which has passed the filter. The sepa- 

 ration of this portion must not be made by a filter, for in this 

 state the chromic acid attacks the paper, and is itself converted 

 into oxide of chrome. 



To prepare the fluosilicic acid in sufficient quantity, M. Maus 

 uses a very large retort with a long neck: he puts into it the 

 mixture of fluor-spar and glass, and adds sulphuric acid, to 

 about three times the amount of the fluor spar in weight, and 

 mixes the whole well. A large globe with a long neck is then 

 provided, and a sufficient quantity of water put into it ; the neck 

 of the retort is introduced ; the globe shaken, to moisten the 

 interior with water, and the fluosilicic gas evolved by the appli- 

 cation of heat. When it arrives in the globe it condenses in the 

 water, and as soon as the quantity of silica produced retards the 

 contact of the gas and water, the globe is again shaken and 

 the operation continued. In this way no gas escapes, and the wa- 

 ter soon becomes saturated with the acid ; the silica is easily se- 

 parated. — Ann. der Phijs. 1827, p. 83. 



