74 United States Coinage. [August, 



It will be observed that the counterfeit must be very nearly, if not 

 exactly, the size of the genuine coin: and it is very difficult to 

 harmonize weight and size when the metals are diliierent in gra- 

 vity or weight. 



The gold eagle of the act of 1837 weighs 258 grains. The 

 silver dollar 412.5 grains. If, then, there is a variation in weight 

 in the gold piece of 3 grains it would make it suspicious; and if 

 more, would condemn it. In silver, only about the same latitude 

 could be admitted in new pieces. 



A Mexican dollar, if forged, and having the fineness of 970, if 

 of the perfect size, would weigh only 402 grains instead of 416, 

 which is its true weight. This composition would be quite 

 liberal; and none but quite an honest rogue would be disposed to 

 employ so much silver in his coin. There is, however, too much 

 irregularity in the weight of the South American dollars to con- 

 demn a piece solely upon a few grains deficiency in weight, or a 

 few grains excess. One counterfeit Mexican dollar weighed 418 

 grains; but others weigh from 30 to 50 grains less. A counter- 

 feit half dollar weighed 213 grains, but others varied from 20 to 30 

 grains. 



Specific gravity is an equally important character with weight, 

 and perhaps more so. As has been already stated, the specific 

 gravity of a body is its weight compared with an equal bulk of 

 water, taken as a standard for comparison. It may always be 

 teken as a sure test for the genuineness of coin, and ought al- 

 ways to be resorted to. The process is this: weigh the piece or 

 a part of it in the air; weigh it suspended by a hair in pure, or 

 rain water, near the temperature of 60 Fah. ; take the dilFerence 

 of the two weights, and divide the weight in air by this differ- 

 ence, and it is the specific gravity sought. Now the specific 

 gravity of gold coin is 17.3, and of silver 10.3. If a spurious 

 gold piece, having one half gold, and one quarter silver, and one 

 quarter copper in it, its specific gravity would be only 12.8 in- 

 stead of 17.3, as it ought to be; a difference which is detectable 

 by the ordinary apothecary's scale, supplied with true weights. 

 Its weight would be too light by 34 grains; and even if it con- 

 tained three fourths gold and the rest silver and copper, it would 

 still be too light by 14 grains. A forged Mexican dollar, with a 

 fineness of 770 instead of 900, would have a specific gravity of 

 9.94 instead of 10.3, as it ought to have. 



It is clear, then, with the ordinary scales and weights used by 

 apothecaries, that a genuine coin can always be distinguished 

 from a spurious one. There is not the least danger of falling into 

 error in the matter when proper care is observed in the weighing. 

 If the size of the counterfeit is the same as the true, it must al- 

 ways be too light; and if its size is increased to bring up the 



