CHEMISTRY. 



. 



Elements bine with indium. Mr Tennant did not succeed in 

 f his attempt to unite.it with sulphur. 



4. It formed alloys with all the metals tried except 

 < arsenic. It does not alter the colour of gold, and 



cannot be separated from gold and silver by cupella- 

 tion. 



SECT. VIII. Of Osmium. 



Osmium. This metal was discovered hy Mr Tennant at the 

 same time with the preceding. It exists in the black 

 powder separated during the solution of crude pla- 

 tina, and may be obtained in solution in potash, by 

 the procest described in the last Section. When sul- 

 phuric acid is mixed with thin solution, and the whole 

 subjected to distillation, a colourless liquid comes 

 over, consisting of water, holding the oxide of os- 

 mium in solution. It has a peculiar smell. Hence 

 the name osmium applied to the metal. When mer- 

 cury is agitated io this solution, the osmium combines 

 with it, and h-aves the water, and by applying heat, 

 the mercury is driven off, and the metal obtained in 

 a state of purity. 



Properties. 1- Osmium has a dark grey or blue colour, and 

 the metallic lustre. In the open air it is easily dissi- 

 pated by heat; but in close vessels, it resists any de- 

 gree of heat without alteration. It is not acted on 

 by any acid, not even the nitro-muriatic, but is easily 

 obtained in solution by the action of potash. 



2. Osmium is easily oxidized by heat in the open 

 air. The oxide has a peculiar smell, and a kind of 

 oily appearance. It is volatile and soluble in water. 

 The solution is colourless, doeo not alter vegetable 

 blues, and strikes first a purple, then a blue, with the 

 infusion of nut-galls. 



3. The action of the simple combustibles on this 

 metal is not yet known. Neither do we know much 

 of its combination with other metals. It amalga- 

 mates with mercury, and Mr Tennant united it by 

 fusion with copper and gold. 



SECT. IX. Of Copper. 



Copper. Copper seems to have been known as early as any 



metal except gold and silver. It was very much em- 

 ployed by the ancients before the method of manu- 

 facturing steel became familiar. 



Properties. 1. Copper has a fine red colour, but it soon tar- 

 nitihes when exposed to the air. Its taste is styptic 

 and nauseous, and when rubbed it emits a disagree- 

 able odour. It is very poisonous when taken inter- 

 nally. It is softer than iron, but harder than gold. 

 Its specific gravity, when pure, is about 8.9. Its 

 malleability and ductility are very considerable. A 

 copper wirf 0.078 inch in diameter is capable of sup- 

 porting 302.2 Ibs. avoirdupois without breaking. It 

 mtlts at 27 Wedgewood, and gradually evaporates 

 in visible fumes. When melted, it has a blui*h green 

 colour, something like that of melted gold. When 

 allowed to cool slowly, it crystallizes in quadrangular 

 pyramids. 



Oiide*. 2. It is not altered though kept under water. 



W-icn heated in contact with air, it is gradually con- 

 verted into a black oxide by the combination of oxy- 

 gen. Before a blow-pipe of oxygen and hydrogen 



gases, it burns with a fine green flame. There are Eiementi 

 two oxides of copper. The protoxide is found na- f 

 turally of a red colour, but when formed artificially 

 it is orange. The peroxide is black. 



The protoxide was first recognised by Mr Proust. 

 It may be prepared by beating together a mixture of 

 equal parts of black oxide and copper in powder in 

 muriatic acid. Almost the whole is dissolved, and 

 the solution is colourless. By pouring potash into 

 the solution, the protoxide precipitates in the state 

 of a yellow powder. This oxide is composed of 

 88.89 parts copper, and 11.11 oxygen. It attracts 

 oxygen with such avidity, that it can scarcely be 

 dried without becoming black. 



The peroxide of copper is easily formed by keep- 

 ing copper filings a sufficient time red hot. It con- 

 tains 80 parts copper, and 20 oxygen. It is black. 

 It combines with water, and forms a blue-coloured 

 matter called hydrate of copper. 



3. Copper has not been combined with hydrogen 

 or carbon ; but it unites with sulphur and phospho- 

 rus, forming the sulphuret and phosphuret of copper. 



When equal parts of sulphur and copper are stra- Sulphurets. 

 tilled in a crucible, they combine at a red heat, and 

 form sulphuret of copper, of a very deep blue colour. 

 It is brittle, and composed of 78 copper and 22 sul- 

 phur. If copper filings and sulphur in powder be 

 mixed, and gradually heated in a flask, they combine 

 before they arc heated to redness; but at the instant 

 of combination, a quantity of heat is evolved suffi- 

 cient to convert the sulphuret into a glowing red, as 

 if in a state of vivid combustion. 



Sulphuret of copper is capable of combining with 

 an additional dose of sulphur, and forming a super- 

 sitlplntret. It is brittle, has a yellow colour, and the 

 metallic lustre. It is found native, and known under 

 the name of copper pyrites. 



Phosphuret of copper may be formed by project- Phosphu- 

 ing phosphorus on red hot copper. It is white, rets- 

 tough but not ductile, hard, and contains the 5th of 

 its weight of phosphorus. When repeatedly melted, 

 it still retains about l-12th of its weight of phos- 

 phorus, and then has much the appearance of steel, 

 and admits of an equally fine polish. 



4 1 . Copper does not combine with azote. 



5. It combines with most of the metals, and some Alloys. 

 of its alloys are of considerable importance. 



Copper unites readily with gold, and eve.n heightens 

 the colour, while it increases the hardness, and does 

 not injure the ductility. Gold coin consists of gold 

 alloyed with copper or silver, or with both. Our 

 coin contains l-12th of alloy, usually both silver and 

 copper. A pound of standard gold is coined into 

 41-4 guineas. 



Platinum combines with copper, but a violent heat 

 is necessary. The alloy is white, hard, ductile, tak>-3 

 a fine polish, and id not liable to tarnish. Hence it 

 has been proposed for the mirrors of telescopes. 



Copper and silvc-r easily unite by fusion. The 

 alloy i: harder and more sonorous than silver, and re- 

 tains its white colour even when the proportion of 

 copper is considerable. Our silver coin consists of 

 12y silver, alloyed with one of copper. A pound of 

 standard silver is coined into 62 shillings. 



Copper may be united to mercury by pouring a 



