294 



Miscellaneous Intelligence. 



2. Apparatus for talcing specific gravity; by Messrs. Eckfeldt and 

 Dubois, (Proc. Amer. Phil. Soc, vi, 193.) — The apparatus for taking spe- 

 cific gravity of solids, is essentially a tin cup with a spout at the side. 

 Five vessels are here shown, of different sizes and shapes, to suit differ- 

 ent cases. Four of these are cylindrical, ranging from six to ten inches 

 high, and from two to five inches in diameter. The tall one (ten inches 

 by two), is intended for the trial of silver spoons and forks, or articles 

 of similar shape ; the others are adapted to lumps of stone or metal, or 

 blocks of wood, of various sizes. The fifth vessel is rectangular, meas- 

 uring 6-J inches high, If inches long, and \ inch broad, being intended 

 for coins, not smaller than the half eagle or quarter dollar, and for 

 small medals and gems of admissible size. This vessel is provided with 

 a brass plate, as a plunger, for diminishing the surface. The smaller 

 vessels are set firmly in mahogany blocks, to insure steadiness in the 

 operation ; and these blocks have screw feet, for convenience of level- 

 ling. The spouts extend upward, with a curve outward, the beak being 

 far enough below the top of the cup to allow for the space to be taken 

 up by the specimen, that it may not force the water over the top nor 

 leave any point uncovered by water. The aperture of the spout is ta- 

 pered to the one-sixteenth of an inch, and a small bit of wire projects 

 downwards from the beak, to carry the drops of water properly. A 

 small cup is placed directly under, to catch the water displaced, and a 

 brass weight, equal to the weight of this cup when empty, is found con- 

 venient (though not necessary) as a counter-weight. 



When the operation is to be performed, suppose upon a gold or silver 

 ore, the ore is first weighed, and afterwards its surface is moistened. 

 The vessel is then nearly filled with water, and so much as is superfluous, 

 or above the level of the beak of the spout, runs or drips off, to a final 

 drop. The small cup is then set under the beak, and the lump is care- 

 fully lowered into the vessel by a hair wire or waxed thread. This, of 

 course, displaces its own bulk of water, which runs off into the small 

 cup, gradually coining back to the former level, by a final drop. The 

 weight of this water is the divisor, the weight of the lump the dividend, 

 and the quotient is the specific gravity. 



In connection with this apparatus, the following miscellaneous remarks 

 are offered to the Society. 



The opening of the gold mines of California brought out a great 

 number of beautiful specimens of gold in the matrix (or mingled with 

 quartz) of the most fanciful forms, and every variety of size and value. 

 In many cases it was presumed, by the holders of these prizes, that they 

 would bring more money, as curiosities, than as bullion ; and at any 

 rate, very many owners were unwilling to have such attractive specimens 

 spoiled until they had been sufficiently exhibited. At the same time, it 

 was always desirable to know, pretty nearly, how much gold was actu- 

 ally contained ; and, to obtain such estimates, upon what was supposed 

 to be reliable authority, many of these specimens were brought to the 

 assay office of the mint. They came at a time when we were overpow- 

 ered with the legitimate business of the office, and yet it seemed impos- 

 sible to refuse such requests ; and, for a considerable time, such employ- 

 ment was interesting as a matter of scientific inquiry. Especially when 

 we could compare our estimates with the more definite and accurate re- 



