Mf . J. Napier 07i Copper Smelting, 353 



dissolves easily in the melted metal, and parts with its oxygen 

 again to the alloy, forming scoria, which differs entirely from 

 the other scorise, being composed principally of the silicate, 

 oxide and metallic copper, with the oxides of the other metals. 

 It forms upon the sm-face in tough irregular masses, which, 

 when cooled, are covered over with crystals of oxide of tin resem- 

 bling threads of glass, the composition of which is stated by 

 Mr. Cameron to be four equivalents of oxygen to one of tin SnO'* 

 (Chemical Gazette for 1851, page 125). The slags contain 

 generally about 60 per cent, of copper. The metal is freed con- 

 siderably from its metallic impurities by this roasting. 



The reader will not have failed to remark that the reduction 

 and purifying of the copper are effected without the aid of car- 

 bonaceous matters of any sort, contrary to what is stated in all 

 chemical books in reference to the reduction of copper ; indeed 

 the addition of carbonaceous matters would be detrimental. 



During the roasting of copper there is a considerable loss of 

 metal, owing to a portion of the oxide being carried away by the 

 draft of the furnace in the form of fine powder. We have seen, 

 where no culvert was connected with the furnace, and proper 

 care not taken, the roof of the house round the chimney covered 

 with suboxide of copper. Where culverts are used, this is nearly 

 all saved j when obtained in the culverts, it is generally com- 

 bined with silica and other matters. A portion fus^d as a qake 

 from a culvert gave— 1 YUBiioi?;ii;>: tjoq i&q., ./ 



"--^ - -1 Silica and d^y ' . : . 60*2 >^^ «' V^^ ^-^ 



Xd n9vi§ tio% Protoxide of iron . . 16*4 ^h&hm>^xi&^^ 



Ifivtam 981JSO; ' Sulphur 1*6 I'^^l oYj^I"^ ^u 



iiodY/ l&y- Lime 1*3 '^iltrMferjii iihi 



^laaaaotqu Tin and* antimony \ \ 4-0 'Oafoa to. 



h^ii-^s^ixi^'y Oxide of copper . . . 15*6 msbi8n.)u 



. M .h,,,,.r :.: ^;. ^ _ 99-1 „,..„., .h't^ 



A portion formed upon the inside of a stack as a fused incrus- 



.^i^Hmi^^iy^OiyyU J^^oluble .... 38-6 d.r-o/irS^ ^w' 



hm m^miiU^^ Oxide of copper . . 27-0 ■ .n^o^ n. 



h^BWiih ^Immp^ Sulphur .... 3-5 -md* 



t/Jfffirrp &d^^>* ^ Sulphuric acid . . 3-4 ^ 



aVrm'riq ii 88 , Tm and antimony . 4-5 to 



tifi;t9i« Qurqmi d ? ±^^^ • • • r*id iM^ni^f^ij-mj^-^fn^ "-■■. oa? 



9dt rii snob a/ - Protoxide of iron . 16-4. . ^ 



loeuoJ ijjoi'ijjo 1^1"^^ 1*6 



aaiflt oi b^iiupsi Manganese^. ^ • ^^l-? -^^ ^' 



\Rm aom& adT Arsenic ^ 'io^£ir,^ttoni^stFt_^^jjk,'> 

 sbao doidwt'iii? f^'j ^^j bssibrxo 8f "^aqfr 99.9 aj^^i ^ 1 



