Miscellaneous Intelligence. 



295 



suits obtained by putting specimens or " nuggets" through the regular 

 routine of melting and assay. On one occasion a lump, weighing over 

 200 pounds, came to us for this purpose. It was sent by the Isthmus 

 route, at a time when transportation was enormously dear, and having 

 visible gold on the surface, was expected to be rich throughout the mass ; 

 and, with this expectation, was on the way to London, to make an im- 

 pression upon the stock market there. By the aids of a very large 

 steelyard beam and copper kettle, we were enabled to take the specific 

 gravity, but could not make it higher than that of compact quartz. The 

 result seemed so questionable, that we obtained permission to break up 

 the rock, and found that what little gold it contained was at the surface. 



Not only were ores brought to us from California, to be estimated, but 

 also from other mining regions, and of various metals ; but chiefly gold 

 and silver. As the specimens were of all sizes, these demands upon us 

 often proved embarrassing, since it was necessary to have beams suited 

 to them, and with attachments for weighing in water. We therefore 

 had frequent recourse to the method advised by the elder Dr. Patterson 

 (formerly President of this Society), which consisted in using a jar or 

 pitcher, rather larger than the specimen, and not over-large at the 

 mouth ; this was filled with water up to a marked line ; and then, by in- 

 troducing the specimen, and bringing back the water to the same line, 

 so much water was removed as was just equal in bulk to the bulk of the 

 specimen ; the weight of this water gave the divisor, the weight of the 

 specimen (taken while dry), the dividend, and the quotient was the spe- 

 cific gravity. 



The results thus obtained were, generally, as satisfactory as those by 

 the usual method. And here it may be interesting to cite a few exam- 

 ples from our minutes, of specimens estimated by one or other of the 

 processes mentioned, and afterwards melted down and assayed as regular 

 deposits. 



1. A lump of quartz, containing gold, found by two Mexicans of the 

 " Sonorian camp," in California, weighed 265-J ounces : assuming the 

 quartz at the sp. gr. of 2-60, the amount of gold appeared by sp. gr. of 

 the lump, to be 209^ ounces; the actual amount was 21 ounces. — 2. 

 Another lump, where we assumed the matrix at 2*64, gave an estimate 

 of 100-J ounces of gold; the actual product was 100 T ^ ounces. — 3. Four 

 pebbles taken together, estimated at 11 ounces; actual content 1 6 T 8 g- 

 ounces. — And, lastly, a lump which had been bought in California for 

 800 dollars, and which weighed 408-J ounces, gave an estimate of 89-J- 

 ounces, or 1572 dollars, taking the matrix at 2'63 ; the actual yield was 

 91 T 2 (y ounces, or 1602 dollars; the fineness being 850 thousandths. In 

 this case there was an error of 30 dollars, or about two per cent, upon 

 the value ; an amount of error to which such specimens are liable, with 

 any apparatus. 



But it was obvious that the method of displacement required a series 

 of vessels specially adapted to the operation, to compete with weighing 

 in closeness of results. After a good deal of reflection and experiment- 

 ing, in which many modifications of shape and arrangement were tried 

 and discarded, and which it would be cumbersome to notice in this 

 place, the apparatus now shown was found to answer best. In practice 

 it is really a pleasant and satisfactory substitute for the tedious and irk- 



