b. One much broader and stronger than a pincers, for detaching small fragments from a specimen, without the formation of much dross. Fig. 18. Fig. 18. c. One of steel-Fig. 19is employed for removing the scoriæ in silver and gold assay Fig. 19. ings, and in various other operations. Its points must be broad, and its inner surfaces rough. d. One of brass, for holding small fragments of minerals, et cetera, in the flame. Fig. 20. Fig. 20. e. One of brass, with points exceedingly fine, for raising the weights, et cetera, and placing the silver and gold globules upon the graduated scale; and, f. One of iron, for trimming the lamp wicks. 5. A MORTAR AND PESTLE of Agate; or of Calcedony, which is preferable. This should be about 24 inches in diameter, of an inch high, and 7-16ths of an inch deep, transparent at the bottom, and free from fissures: they are not only applicable to the pulve Fig. 21. rization of substances that are to 6. A HAMMER.-This instrument should be of hardened steel, similar in shape to Fig. 21. When the broad sharp end becomes blunt from continued usage, it may be easily repaired by applying it with force to the grinding-stone. 7. AN ANVIL.-A polished anvil, of hardened steel-Fig. 22-will be found exceedingly useful in the laboratory, for crushing minerals, ores, et cetera. It should be in the form of a paral Fig. 22. lelopiped about 24 inches long, ; 1 inch in diameter, and of an inch in thickness. When a substance is to be broken into fragments, it must first be wrapped in strong paper, placed upon the instru ment, and then struck sharply with the hammer. Should the paper, in this process, be torn, and thrown off the face of the anvil, the malleable particles will be found adhering to it, and may be examined separately. Fig. 23. F If a mineral is to be heated upon charcoal before the Blowpipe, it can be reduced to small pieces in a machine similar to that below. As it is frequently employed in the quantitative examination of minerals, it will be described :-Upon a hardened steel plate, AB,―Fig. 23,—is a depression c, containing a hollow cylinder, D E, which is completely filled by a massive cylinder F, hemispherical at the end. The two cylinders, D E and F, are also hardened steel, well ground. When a mineral is to be pulverized, F is removed, and the substance is placed in the hollow cylinder, D E; the cylinder F is replaced, and struck forcibly with a mallet. When the two cylinders are separated, the substance will be found reduced to a rough powder. A D E B If necessary, this powder can be brought to an impalpable state in an agate mortar. 8. CHARCOAL BORERS.-For quantitative Blowpipe analysis, grooves of various dimensions are bored in the charcoal that serves as a support. There are three different borers, of hardened steel, which will be here described :— a. A borer, of the form of Fig. 24, for making a cylindrical cavity, in which silver, gold, or copper may be heated. It is a four-sided pyramid, the sides being ground from below with a three-edged file, so that it appears like a double chisel, crossing at a right angle. Its under diameter is one-third of an inch. This instrument may be held in a wooden case, containing a brass ring. Fig. 24. When a groove is to be made with the borer, it is placed at a right angle, with the charcoal, pressed upon it with force, and turned upon its axis until the groove is sufficiently deep. The instrument is then withdrawn, and the charcoal-dust removed from the cavity. A silver assay should have a deeper groove than a copper one, owing to the former metal requiring, when operated upon, to be mixed with lead. Fig. 25. b. A second Charcoal borer, for forming larger grooves, Fig. 25. Its upper diameter is seven-eighths of an inch, and its length three-fourths of an inch. This borer is handled in the same manner as the preceding one for the formation of grooves in the charcoal. The cavity formed by this instrument Fig. 26. serves as a support in roasting different substances whose metallic contents are to be determined quantitatively. c. A third Charcoal borer, similar to Fig. 26, has one end of the same form as that first described, but the double chisel is only 3-16ths of an inch in diameter, and is employed for making incisions in the charcoal, to contain quantitative lead and tin assays. The other end has a diameter of of an inch, it is sharp like a spatula, and serves to make small grooves for qualitative experiments. 9. A CHARCOAL SAW.-This instrument should have very fine teeth, for cutting with ease long pieces of Charcoal. The most useful size is five inches in length, three-eighths of an inch in breadth, one sixteenth of an inch in thickness. It should be provided with a wooden handle, three inches in length. 10. A CHARCOAL HOLDER.-In quantitative assayings, which are to be melted without the accession of atmospheric air, the charcoal must be encased in iron foil. Fig. 27 represents several sections of this instrument. Its sides are 18 inch in breadth, and 14 inch in height. At the anterior side, B, it is provided with a round opening, a, terminating at b; and at the reverse, is a small iron screw, c, provided with a wooded case, e, on whose inner end is an iron disc, d, which revolves round its axis. h a B The screw, c, is under the middle of the charcoal holder, and prevents the cessation of pressure, when the charcoal is gradually consumed from above. The screw, f, is made of brass, and can readily be removed, because it is inserted at g. A small iron plate, h, is fastened, by a rivet, to the face of the charcoal holder, so that the incision, b, can be opened or closed, as the figure shows. On the right side, ▲, of the instrument, is a small opening, i, a quarter of an inch in length, for the reception of the platinum wire, to be described hereafter; and under this aperture is a small brass case, k, for holding its end. 11. PLATINUM WIRE AND FOIL.-When an ore is to be roasted, or an assay melted, in a clay basin, the latter must be supported by some substance placed in the cavity of the charcoal. For this |