262 METALLURGY. 



the brass far more ductile, and filter for the making of fine v 

 than it wou'd be wi'hout i( ; hut tlu- German brass, particularly 

 that mde at Nuernberg, is, when dnwn into wire, said to be 

 preferable to any made in England for musical instruments. If this 

 preference be real, it will cease to exist as soon as any ingenious 

 man shall undertake to examine the subject; for our materials for 

 making brass are as good as any in the world. The quantity of 

 charcoal, which is used, is not the same at all works ; it is gene- 

 rally about u fourth part of the weight of the calamine : an excess 

 of charcoal can be attended with no othi r inconvenience than that 

 of uselessly filling up the pots in which the brass is made; but 

 powdered pitcoal which is used at some works in conjunction with, 

 or in the place of charcoal, greatly injures the malleability of the 

 brass. As to black jack, the other ore of zinc, it is not so com. 

 rnonly used as calamine for the making of brass. The manufactur. 

 ers have been somewhat capricious in their sentiments concerning 

 it ; some have preferred it to calamine, and others have wholly 

 neglected it; and the same persons at different times have made 

 great use of it, or entirely laid it aside. There must have been 

 some uncertainty in the produce or goodness of brass made by this 

 mineral, to have occasioned such different opinions concerning it ; 

 and this uncertainty may have proceeded either from the variable 

 qualities of the mineral itself, or from the unskilfulness of the 

 op 1 rators in calcining, &<:. a mineral to which they had not been 

 much accustomed. Several ship loads of it were sent a few years 

 a_i> from Cornwall to Bristol, at the price of forty shillings down 

 to a inoidore a tt>n*. Upon the whole, however, experience has 

 not brought it into reputation at Bristol. 



I'"or many purpo-.es bra<s is more useful than copper ; it is 

 lighti r, harder, more sonorous, more fusible, less liable to scale 

 in the fire, and to rust in the air. It is not malleable when hot, 

 and in this n-pect it is inferior to copper : but when cold it may 

 be beat out into thin leaves, as may be seen in the brass leaf, which 

 emiila't-s in colour and thinness gold leaf. If a brass leaf be held 

 in tin- Hume of a candle, the metallic part of the calamine will be 

 inflamed, and the brass will he changed into copper. This change 

 of brass into t:opp r will take place in the largest masses, as well 

 as iti ti.in leavis of it if the brass he kept a sufficient time in a 



* Miner. Cornu. p. 47. 



