The second specimen had the appearance of compact oxide of iron, containing here and there milk-white quartz; it was throughout impregnated with chloride of silver, which occasionally appeared in the form of very small brilliant crystals. To analyze this mineral, 10 grammes were first treated with ammonia, and heat to dissolve the chloride of silver, and afterwards by boiling hydrochloric acid to dissolve the oxide of iron; this acid also dissolved a certain portion of lead, which probably was in the state of phosphate. The quartzose residue weighed 32.6 grammes: it contained 0.17 gramme of silver, which must have been in the metallic state: the ammoniacal solution gave by boiling and saturation with nitric acid, 1.84 gramme of chloride of silver, which, supposing it to be pure, contained 1.40 gramme of silver, which, added to 0.17 gramme remaining in the quartz, gives a total of 1.57 gramme; a result which differed so very little from that obtained by essaying, as to prove the absence of bromide of silver, and that this was the case was confirmed by additional experiments. After this a third specimen was received from Huelgoeth; it was very small, but as rich as the foregoing, and in it there were distinguishable, besides granular cubic crystals of chloride of silver, other grains of an olive-green color, which had exactly the same appearance as the bromide had. Plateros and the following experiments proved the presence of the substance. Five grammes of the pulverized mineral were boiled in a solution of oxalic acid, until the oxide of iron was perfectly dissolved: the residue weighed about a gramme, and it evidently contained a mixture of canary-yellow and white grains. It was digested in hot solution of ammonia until all the yellow powder disappeared; it required a large quantity of the alkali for this purpose, which would not have been the case to dissolve pure chloride. The solution was gradually saturated with nitric acid, and it was observed that the successive deposits formed had an evident yellow tint, but gradually diminishing in intensity, except the last, which were white. The yellow deposits were collected and examined in the following manner:--A portion was treated with chlorine and æther; the æther became of a yellow color. Another portion was dissolved in ammonia, hydrosulphate of ammonia was added to the solution, and the black precipitate formed was separated, and was found to be pure sulphuret of silver. The liquor was concentrated by exposure to the air, and filtered to separate the sulphur which was deposited; a little potash was then added, and it was evaporated to dryness; acetic acid was added to saturate the excess of potash, and it was again dried.