China.] 



ORIENTAL COMMERCE. 



485 



than the interior part ; and it often happens that lumps of other metals are 

 mixed with it, generally silver. 



When the mass is much adulterated, the fraud can be discovered at 

 sight, the middle being elevated instead of depressed, and the sides uneven 

 and knobby. If it is suspected to be gilt with a thick coat of metal, finer 

 than the internal part, it should be raised with a graver or chisel to some 

 depth, so that the exterior coat may be broken through : cutting the piece 

 in two is a less certain way of discovering this abuse, the outer coat being 

 frequently drawn along with the chisel so as to cover the divided parts. 



Gold, when pure, is of a full yellow colour ; it is never obscured with 

 tarnish or rust. When alloyed with copper, the colour inclines to a reddish 

 hue ; silver makes it pale, and if the proportion of silver be as one to four, 

 a greenish hue is produced. 



Tbe degree of fineness of gold, or the proportion of alloy it contains, 

 is accounted by imaginary weights called carats. The whole mass is con- 

 ceived to be divided into 24 parts, or carats, and so many twenty-fourth 

 parts as it contains of pure gold, it is called gold of so many carats, or so 

 many carats fine. Thus gold of 18 carats is a mixture of which 18 parts 

 in 24 are pure gold, and the other 6 parts an inferior metal ; and in like 

 manner gold of 20 carats contain 20 parts of pure gold and 4 of alloy. The 

 standard of the English gold coin is 22 carats fine, so that in a guinea there 

 are 22 parts of pure gold and 2 parts of alloy. 



Those who are accustomed to the inspection of gold, variously alloyed, 

 can judge nearly, from the colour of any given mass, the proportion of 

 alloy it contains, provided the species of alloy is known. Different com- 

 positions of gold with different proportions of the metals which it is com- 

 monly alloyed with, are formed into oblong pieces, called needles, and kept 

 in readiness for assisting in this examination, as standards of comparison. 



The proportions in the composition of tbe several needles are adjusted 

 in a regular series, according to the carat weights before explained. The 

 first needle consists of fine gold, or of 24 carats; the second of 23| carats 

 of fine gold, and half a carat of alloy ; the third of 23 carats of fine gold, 

 and one carat of alloy ; and so on, the gold diminishing, and the alloy 

 increasing, by half a carat in each needle, down to tbe twentieth carat; all 

 below this are made at differences of whole carats, half a carat being 

 scarcely distinguishable by the colour of the mass, when the proportion of 

 alloy is so considerable. Some make the needles no lower than to twelve 

 carats, that is, a mixture of equal parts of gold and alloy ; others go as low 

 as one carat, or one part of gold to twenty-three of alloy. 



Four sets of these needles are commonly directed : one in which pure 

 silver is used for the alloy ; another with I mixture of two parts of silver, 



