TINNING COPPER, 8CC. 301 



was found in no part of Europe in so pure a state, nor in so great 

 plenty a> in KnJ MI . 



Burlasc and I'ryce, who have written so minutely on the method 

 of prepirin;; the tin in <>r w.r'. ire both of them silent, as to any 

 operation 'h<- tin un<l -i^oes snbseq'i'"it to its coinage; nur do 

 they say a:u thing of its bein mixed with other metallic substances 

 previous t> is coinage; but aivin* us, uut t)i it llowg. 



from (he ore. i- la '. .i into troughs, each of which contains a') ut 

 three hun.'rid pounds weight of metal, called slabs, blocks, or 

 pieo ir ntn'fh s ze tnd form it i-> so d in every market in 



is. however, in general assert, that our tin as 

 exported is a mixed metal ; and the French Encyclopedists in par. 

 ticular (article Ctain) inform u>, on the authority of Mr. llouelle, 

 that the virgin tin is again malted and cast into iron moulds of half 

 afoot in thickness; that the metal is .cooled very slowly; that 

 when cold it is divided horizontally into three layers ; that the up. 

 permost, being very soft pure tin, is afterwards mixed with cop. 

 per, in the proportion of 3 pounds of copper to 100 of tin ; that 

 the second layer, being of a harsher nature, has 5 pounds of lead 

 added to 100 of the tin ; and that the lowest layer is mixed with 

 9 pounds of lead to an hundred of the tin ; the whole is then re. 

 melted, and cooled quickly ; and this, they say, is the ordinary tii\ 

 of Knglaud : and Geoffroy had formerly given much the same ac- 

 count*. There is, probably, no other foundation for this report, 

 but that pewter has been mistaken for tin, these metals being some. 

 times calli.d by the same name; and fine pewter being sometimes 

 made from a mixture of 1 part of copper with 20 or 30 parts of 

 tin. 



The mixture generally used for the tinning of copper vesselsi 

 consists of 3 pounds of lead, and of 5 pounds of pewter ; when a 

 finer composition is required, ten parts of lead are mixed with six- 

 teen of tin ; or one part of lead with two of tin: but the proportions 

 in which lead and tin are mixed together, even for the same kind 

 of work, are not every where the same; different artists having dif. 



* f'isores aperto furni osliolo, me tallum in fonnas qiiasdam ex arena 

 paratas difiluerc sinunt, ibiquc in massas grandiores concrescit. Superior 

 stannese mas -IT. pars adeo molds est et flexili-. ut sola eluboruri nequeat sine 

 cuprt miHela, trium scilicet lihrarum super stanni libras centum. Ma'ije |>ari 

 media binas un'um rupri libras recipit. lotiroa vero adeo fragihs < *t et in- 

 tractabilis, ut cum liujus metalli centum lit>ri plumbi libra* octudecim con- 

 tociare oporteat. Geoff. Mat. Med. vol. I. p. *. 



