288 



8C1ENTIFIC INTELLIGENCE. 



[1853 



S ft 



« ": ^ r>; 

 o 1--; t-; o 



iTj o to — 5 



>t .9 



s 

 a 5 



g 



o boa 



M 2 .a o ;= p , 



i ='■'5 2 '^ ^ 





■fe ~ = --o n a 



o.= s != a 5 CI 

 •^..t^ ^-^ = rt :: >, 



"^"S} ^ ^ r Jl"^ 





- -=: = 3 3 

 ■ 3 H, '/" « 





TixxiNG Iron.— Articles iutcuded for tinuing must first be rendered 

 pcrfeelly elean by immersion for a short time in a batli of 4 ibs. iniiri- 

 .-itic acid to three gallons of water, expo.sure for a short time at a i-ed 

 heat, Ktce])inc 10 or 12 hours in a dye of bran, and pickling (as it is 

 called) ill dilute sulphuric acid for about an hour. They, are then 

 rinsed with water, scoured with hemp and sand, and left in a bath of 

 pure water until wanted. These various operations require some ex- 

 perience to manage tliem rightly. The plates, are then dried by rub- 

 bing with bran, and left .'kingly, for about an hour, in pots of melted 

 grease, which should liave been slightly burnt They aiethen removed 



with the grease adhering to them, into the metal bath, consisting of 

 equal parts of block and grain tin, covered with grease, enough to 

 form a layer about 4 inches deep. The bath is heated so as almost to 

 inflame the grease. In about 90 minutes Ihey are taken out, and 

 plunged into another bath of pure grain tin; then rnljlied ^^•ith a ]iecu- 

 liar hempen brush, plunged agaiu into the second balli, and tinally in 

 a pot of melted t;dlow. Saucepans are generally tinned by cleaning 

 the inside jicrfectly, heating the vessel, pouring in some melted tin, 

 and I'olling it about, rubbing the tin all over the surface w ith tow. 

 I'owdered resin is used to prevent the formation of o.vide.— ..lrii.:an. 



