ON A NATURAL ALLOY OF SILVER AND COPPER. VIL-On a Natural Alloy of Silver and Copperfrom Chile. By MR. FREDERICK FIELD. The alloy was taken from a mine about twenty leagues east of Coquirnbo and six from the Cordillera of the Andes. It was perfectly free from oxygen sulphur &c. and other sub- stances usually found combined with metals in nature having exactly the appearance of an artificially smelted product from a copper furnace. 100 grs. taken from the centre ofa large mass was found to contain on analysis Copper . 98.91 Silver . 1.09 100~00 The quantity of silver however was very variable. One portion of the alloy had almost a whitish appearance and on being separated by the chisel and analysed gave Copper . . 92.40 Silver . 7.60 100*00 I have a large specimen weighing more than a pound which I hope to have the pleasure of sending to the Society’s Museum by the first opportunity. Feb. 18 1850. The PRESIDENT in the Chair. The Rev. Bath Power and H. Yates Finch Esq. were elected Fellows of the Society. The following Papers were read ‘‘ On some Salts of Chromic Acid,’’ by Mr. J. Danson.