234 



ANNUAL OF SCIENTIFIC DISCOVERY. 



furnace, especially the tymp stone, remained in a much better state of 

 preservation than when limestone was used. The following table gives 

 the quantities of coke consumed, in the production of 100 kilogrms. 

 raw iron, in the above-mentioned furnace, during the four months be- 

 fore and the four months after the alteration of the charo-ino- : 



WITH LIMESTONE. 



1849 March 

 April . 

 May . 

 June . 



150 kilogr. 

 154-5 " 

 1565 " 

 151-5 



u 



Average quan. 153-2 



WITH BURNT LIME. 



1849 July 142 kilogr. 



August. . . . 133 u 



September . . 133 " 



October . . 139 " 



Average quan. 137'75 " 



Average quantity consumed with limestone, . . 153-20 or 100 p. cent. coke. 

 Average quantity consumed with burnt lime, . 137-75 or 90 p. cent. coke. 



Difference, 15-45 or 10 per cent. 



REGENERATION OF BURNT STEEL. 



M. Marbury, of Prussia, has proposed to regenerate burnt steel by 

 heating it to a red heat, and putting it, when in that state, into boil- 

 ing water. Repeated experiments at the Royal Mint at Berlin, have 

 proved perfectly successful. 



TO REMOVE TIN FROM COPPER VESSELS. 



There are many instances in which it is desirable to remove tin 

 from copper vessels, which is accomplished in the most perfect man- 

 ner by immersing the vessels in a solution of blue vitriol. The tin 

 disappears entirely and the copper gets as bright as when new. Old 

 tinned copper brings a low price on account of the tin which mixes 

 with the copper when melted ; by this simple method such copper can 

 be made more valuable. 



ON THE PURIFICATION OF GRAPHITE. 



A German chemist has recently ascertained that impure and cheap 

 graphite may be rendered pure, and fit for the manufacture of lead- 

 pencils, by pulverizing and digesting for 36 hours in strong sulphuric 

 acid. The best English graphite is now worth $1 30 per Ib. ; the 

 price of ordinary graphite fit for refinery is merely nominal. 



FIRE-PROOF BRONZE COLOR FOR COPPER AND BRASS. 



One-sixteenth of an ounce of crystalized verdigris, and the same 

 quantity of finely pounded muriate of ammonia, are to be dissolved in 

 5-6ths of a pint of rain water, the solution left standing covered for 3 to 

 4 hours, and then 1^- pint more water poured into it. The copper 

 vessel, which must be perfectly clean, is now to be held over a char- 

 coal fire until it is equally heated throughout and becomes uniformly 

 tarnished. The copper is now to be rubbed over with the mixture 

 and then carefully dried. 



