METALS. 



79 



Metal*, to dissolve the copper and zinc precipitated by the 

 "Y""" 1 lulpheretted hydrogen. In this way carbonate of cad- 

 mium is obtained, the carbonic acid of which U ex- 

 pelled by heat. The oxide is then reduced by ex- 

 posing it with charcoal to a high temperature. Cad- 

 mium u of a light whitish colour, inclining to grey, 

 very nearly resembling that of tin. It po-sesses con- 

 siderable brilliancy, and take* oo a fine polish. It is 

 of a compact texture, and possesses also considerable 

 lustre. It is likewise very ductile, and may be beat in- 

 to thin plates. 



The specific gravity of cadmium at 62 is 8.604. After 

 being hammered, ita specific gravity is increased to 

 8.694. 



Cadmium, when subjected to caloric, fuses, and on 

 cooling, it crystallises in octahanlrons. At a tempera- 

 ture not much exceeding that of the boiling point of 

 mercury, it passes into vapour, which has no peculiar 

 odour, and which condenses in small drops, exhibiting 

 a crystalline structure. 



By mere exposure to the air, cadmium does not un- 

 dergo any change. 



Uhen heated in contact with atmospherical air, it 

 takes fin, and forms a brownish yellow oxide. 



(Jfute ofcadmiitm. Cadmium has ben made to unite 

 with only one proportion of oxygen. 

 has a yellowUh-gree 



The oxide 



colour, which. 



however, by exposure to heat, becomes yellow. If the 

 at ion of the heat be long continued, the oxide 



brown. These changes in the colour arc sop- 

 posed to be owing to the diftteiue in the cohesion of 

 the body ; for when they are dissolved by an acid, the 



The oxide of cadmium doe* not undergo any parti- 

 cular change by the application of heat to it When 

 slept at a white beat m si covered crucible for some 



time, it did not undergo fusicn. When heated in con- 

 tact with charcoal, it m reduced, the reduction taking 



place at about a red beat. 

 The oxide of cadmium is 

 100 



From this it is inferred that the equivalent 

 for the metal is 69.677, that of oxygen being 1. 



Pkotpkurtt of Cadmium. Cadmium combines with 

 and forms a grey-coloured compound, 

 n very brittle, and baa a slight metallic lus- 



tre. When pot on burning eoalf, it emits a beautiful 

 name, and is cesj verted into phosphate of cadmium. 

 Muriatic sod decomposes it with the evolution rf bos- 

 poimttcu njrdrojprn. 



i of Cmmimum. 



pbiv ; the smlpboret i 

 tng together the oxi 



Cadmium unites with sul- 



formed by heat. 

 It has a yellow 



oxide and sulphur. It has a yellow 

 when cold, but when exposed to heat k fat De- 

 brawn, and than crimson. At a white beat it 

 fuses, and on cooling crystallizes in transparent yellow 

 Sulphur** of cadmium is decomposed by strong 

 ' : acid, with the disenaWaeaent of sulphuretted 

 It is composed e? ' 



100 CttdflBMsflL i 



28.172 sulphur. 

 It ii rffUManiulml as a good pigment. 



CUoridt of Cadmium, is obtained in recUay|ai 

 s, which, when aubiected to beat, sublime and ef- 

 re to the air. It is mtnposad of 

 61.39 cadmium, 

 M.6l chlorine. 

 Iodide of Cadmntm i. obtained in heuedral transpa. 



rent colourless tables, which are decomposed at a Metal*, 

 strong heat, and part of the iodine escapes. It is not l *^"Y"^ i 

 altered on exposure to the air, and is not soluble in 

 water. It U composed of 



100 cadmium, 

 227.4.3 iodine. 



The oxide of cadmium unites with acids, and forms 

 with these, salts, which are in general of a white 

 colour. It is insoluble in the fixed alkalies. Ammo- 

 nia, however, dissolves it. It is also soluble in carbo- 

 nate of ammonia. Cadmium is acted on by nitric acid, 

 nitric oxide being disengaged during the solution. It 

 is also dissolved, though slowly, by sulphuric and mu- 

 riatic acids, accompanied with the evolution of hy- 

 drogen. 



The salts of cadmium are decomposed by thenlkalic--. 

 By the addition of potassa or soda to the solution of 

 the nitrate, the sulphate, or muriate, a precipitate of a 

 white colour is thrown down, which is not soluble in 

 an excess of alkali. The precipitate is supposed to be 

 the yellow oxide, in combination with water, which 

 gives it the white colour. By the addition of ammo- 

 nia to these salts, the same precipitate is formed, but 

 is dissolved on adding an excess of the alkali. 



Sulphuretted hydrogen, and the hydro-sulphuret of 

 an alkali, throw down a yellow precipitate, which, 

 when dried, acquires an orange yellow colour, some- 

 thing similar to orpiment. The precipitate formed in 

 this case is considered a hydro-sulphuret ; it is recom- 

 mended a* a yellow pigment, for which, from its dura- 

 bility, it seems well adapted. 



-iate of potasu, when added to a solution of a 

 salt of cadmium, throws down a white precipitate 

 Cadmium is precipitated in the metallic state, from a 

 sole* ion of any of its salts by sine, the precipitate put- 

 ting on the dendritic form. On the contrary, when a 

 piece of cadmium is put into a solution of a salt of 

 gold, silver, copper, or lead, these metals are precipi. 

 tated. 



\ttrale of cadmium crystallines in prisms, and is de- 

 liquescent. It is composed of 

 110 acid 

 1 1 7.50 oxide. 



Carbomale of Cadmium i* insoluble in water. Its 

 Component parts are 100 acid, 



292.88 oxide. 



PhotphaU of Cadmium is also insoluble. When ex- 

 posed to a red beat it melts into a transparent glass. 

 It is composed of 100 acid, 



285.49 oxide. 



BoraU of Cadmium is little soluble. When dry it in 

 MBBpated of 27.88 n. 



72.12 oxide. 



Sulphntt nf Cadmium is obtained in large rectangular 

 transparent crystals, which are very soluble in water. 

 It is efflorescent, and whan exposed to a strong heat if 

 decomposed, and forms a sub-sulphate. The sulphate 

 is composed of 100 acid, 



16 1. 1 2 oxide. 

 tie nf Cadmium is soluble and crystallixable. 



T'lHratt and Citrate of Cadmium are little soluble, 



Oxalait of Cadmium is insoluble. 



Cadmium unites with other metals, and forms alloys, 

 which arc brittle. 



The alloy ifiik copper has a slight tinge of yellow. 

 By the application of a strong heat to it the cadmium 

 U volatilized. It is composed l 

 100 copper, 

 81.2 cadmium. 



