356 Mr. Croft on some Salts of Cadmium. 



0*6835.gr. of ammonia, or 100 parts absorbed 53*56; accord- 

 ing to the formula Cd CI + 3 N H 3 it would be 56*47 : the 

 difference probably arises from the great increase in bulk 

 which the salt undergoes, and which may prevent the ammo- 

 nia reaching every particle. 



This compound loses ammonia when exposed to the air ; 

 when it has ceased to smell of ammonia, it is converted into 

 the first-mentioned compound, viz. that containing one atom 

 of ammonia. 



Bromide of cadmium crystallizes in long prisms somewhat 

 similar to nitre ; it loses its water of crystallization when ex- 

 posed to a dry atmosphere : 2*422 grs. lost, when heated to 

 100°, 0*5075 gr. of water; that is, 20*95 per cent; accord- 

 ing to the formula Cd Br + 4 aq it should be 21*17 : it fuses 

 easily and crystallizes on cooling. Bromide of cadmium dis- 

 solves in hot caustic ammonia, and gives on cooling a granu- 

 lar crystalline powder; by slow cooling the salt is deposited 

 in the form of regular octohedrons. It contains 11*69 per 

 cent, of ammonia, or 1 atom, and is therefore analogous to 

 the chloride/ 



The anhydrous bromide absorbs a large quantity of ammo- 

 nia, like the chloride, but the quantity varies between two and 

 three atoms*. 



All these compounds are decomposed by water, and oxide 

 of cadmium is separated. 



The chloride, bromide and iodide of cadmium form very 

 beautiful double salts with the alkaline chlorides, bromides 

 and iodides. 



They may be prepared by dissolving the respective salts in 

 atomic proportions. 



Cadmio-chloride of potassium. — From the concentrated so- 

 lution the salts crystallize in silky needles which contain 

 water. If these crystals be allowed to stand in the solution 

 they gradually disappear, and large crystals are formed in their 

 stead ; they have the form of regular rhombohedrons ; they 

 contain no water. Their formula is Cd CI + KC1; the aci- 

 cular salt contains one atom of water. 100 parts of water at 

 60° F. dissolve 33*45. 



Cadmio-bromide of potassium is precisely similar to the 

 double chloride : it is, however, much more soluble in water. 

 Formula Cd Br + KBr. The acicular salt contains water. 



Cadmio-iodide, &c, does not crystallize like the bromide 



* In the last number of the Reports of the Academy of Berlin, I find 

 that Raramelsberg has prepared and analysed the crystallized bromide and 

 its compounds with ammonia. That prepared in the dry way contains, as 

 he says, two atoms of ammonia. 



