Intelligence and Miscellaneous Articles. 225 



scarcely altered, the granite ones have lost a considerable portion of 

 their surface, which falls off continually in scales, and exhibits every- 

 where stains from the formation of peroxide of iron. The kaolin or 

 clay used in most countries for the manufacture of fine porcelain or 

 china is generally produced from the felspar of decomposing granite, 

 in which case the cause of decay is the dissolution and separation of 

 the alkaline ingredients. Water is capable of dissolving in larger or 

 smaller proportions most compound bodies ; and the calcareous and 

 alkaline elements of stones are particularly liable to this kind of 

 operation. 



When water holds in solution carbonic acid, which is always the 

 case when it is precipitated from the atmosphere, its power of dis- 

 solving carbonate of lime is very much increased ; and in the neigh- 

 bourhood of great cities, where the atmosphere contains a large pro- 

 portion of this principle, the solvent powers upon the marble exposed 

 to it must be greatest. Whoever examines the marble statues in the 

 British Museum, which have been removed from the exterior of the 

 Parthenon, will be convinced that they have suffered from this agency ; 

 and an effect so distinct in the pure atmosphere and temperate climate 

 of Athens, must be on a higher scale in the vicinity of other great 

 European cities, where the consumption of fuel produces carbonic 

 acid in large quantities. — Jameson's Journal, April 1 830. 



PREPARATION OF BROMINE AND ITS HYDRATE. 



The mother-liquors containing bromine are to be evaporated to a 

 fourth of their volume in iron pans, and then left for several days ; in 

 which time the larger part of the chloride of calcium crystallizes. The 

 supernatant liquor, being diluted with water, is to be mixed with 

 sulphuric acid as long as a precipitate is formed. The liquid portion 

 being separated, and the solid residue pressed, all the fluid is to be 

 mingled and evaporated to dryness, and then redissolved, that a cer- 

 tain quantity of sulphate of lime may be removed. On acting upon 

 the solution by sulphuric acid and peroxide of manganese, and then 

 distilling, bromine is obtained. 



Hydrate of Bromine. — This compound is easily formed at a tem- 

 perature of from 39° to 43° Fahrenheit, by making the vapour of 

 bromine pass into a tube moistened with water j in about a quarter 

 of an hour the tube is filled with solid hydrate. — Ann. der Phys. xiv. 

 485. Roy. Inst. Journ. April 1830. 



DETECTION OF IODINE. 



M. Balard's process for the detection of iodine, which consists in 

 mixing the fluid to be examined with starch, sulphuric acid, and 

 chlorine, is the most delicate that is known. 



M. Casaseca has remarked, that when the quantity of hydriodate is 

 very small, the blue indicating ring cannot be seen at the part where 

 the solution of chlorine is in contact with the water containing the 

 starch and acid ; then the whole should be strongly agitated and left 

 for a while, when the starch acquires a distinct violet colour. One 

 part of hydriodate of potash was dissolved in two parts of distilled 



N. S. Vol. 8. No. 45. Sept. 1830. 2 G water j 



