Chemical Science. 209 



whole surface of a single crystal, and extends to the most remote 

 angle if a group of crystals be the subject of experiment. This 

 change of colour is accompanied by a sensible mechanical action, 

 so that a small heap of the crystals appear as if animated. An 

 ordinary electroscope does not indicate the development of any 

 electricity, nor is there any considerable elevation of temperature 

 during the change. 



By gently warming the crystals, supported on paper over the 

 flame of a lamp, the original yellow coloured salt is obtained, and 

 the same experiment may be often repeated : aflfording an elegant 

 illustration of the connexion between colours and the mechanical 

 structure of bodies. Transparent, but minute rhombic prisms of 

 this salt may be obtained by allowing a hot solution of it, in a 

 solution of corrosive sublimate, to cool very gradually. — SUli- 

 mans Journal. 



14. On a new Compound of Mercury, by Mr. Phillips. — On 

 adding carbonate of lime to a solution of corrosive sublimate, 

 and heating the mixture, a dark coloured precipitate was formed, 

 crystalline, very heavy, and the larger crystals nearly black j very 

 slightly soluble in boiling water and scarcely at all in cold. It 

 dissolved in acids, and gave peroxide of mercury by potash, and 

 chloride of silver by nitrate of silver. 



Upon trial it was found that no excess of carbonate of lime 

 rendered the change of the corrosive sublimate complete, the 

 muriate of lime formed at the same time producing a counteracting 

 effect. When hard carbonate of lime, as calcareous spar, was put 

 into the corrosive sublimate solution, months were required to 

 obtain only a few crystals of salt. Powdered and precipitated 

 carbonate of lime acted more readily. 



The following process gave the new compound quite pure : 272 

 grains or 1 atom of corrosive sublimate was dissolved in water, 

 and boiled with 648 grains or 3 atoms of peroxide of mercury j a 

 dark precipitate soon began to form, and eventually nearly the 

 whole became the particular substance. Corrosive sublimate, equi- 

 valent to 6 grains of peroxide, only remained undecomposed, and 

 of course some peroxide remained diffused through the precipi- 

 tate ; this may be removed by boiling the whole with about 100 

 grains of muriatic acid diluted with water j the salt is then per- 

 fectly black, dense, crystalline, and frequently very brilliant. 



Mr. Phillips calls this substance a dipermuriate of mercury ; 

 considering it not as a compound of oxide and chloride of mer- 

 cury, with water of crystallization, but of muriatic acid and oxide 

 of mercury. That it contains no water of crystallization is con- 

 sidered as proved, because, when the crystals are put into a glass 

 tube, and the latter heated in a salt water bath, no moisture rises 

 from them, and the crystals undergo no change. At a higher 

 temperature, water, corrosive sublimate, mercury, and calomel, 

 are produced. 



JAN.— MARCH, 1830. P 



