VI. Tools and Implements.

19. GENERAL REMARKS.

We will only consider the tools and implements required for the dry method, as those for the wet method1 do not differ from those used in analytical chemistry (stands, forceps, crucible tongs, cork drill, etc.).

20. FURNACE TOOLS.

The following tools are used in attending the furnaces. Shovels with perforated blades for handling the fuel; large and small iron pokers and scrapers for cleansing the grate and muffle, poking the coal, etc.; coal and ash sieves with meshes respectively 1 centimeter (0.39 inch) and 3 millimeters (0.11 inch) wide; iron boxes filled with water for cooling the tools, etc.

21. IMPLEMENTS.

The following are required :—

A. For preparing the assay sample.

1. Sampling.-Iron spoons having a diameter of 4 centimeters (1.57 inches); shovels; troughs, wooden boxes, etc., for the reception of the assay samples; files and cold chisels; hollow chisels; drills; hollow cylinders of sheet iron for small ore; magnifying glass, etc.

2. For drying the samples (p. 26).—Drying pans of sheet iron or copper; drying frames; iron spatulas; dry

1 Neuere Geräthschaften in Fresenius' Ztschr. f. analyt. Chemie.

ing disk (Fig. 2, p. 26); water-baths (Fig. 1, p. 26); airbaths; desiccators (Fig. 17a, p. 43), etc.

3. For comminuting the samples (p. 27).-Grinding plate and rubber; mortars; hammers; anvils; rolls; common scissors and plate shears; files; rasps; pliers; vise, etc.

4. For sifting.-A series of sieves of from 20 to 100 meshes to the inch, for sifting ores, fluxes, etc. A box sieve, consisting of a round tin box, into which a sieve can be snugly fitted, is very useful, as in sieving the pulverized ore there is no dust. If desired, a tin cover can be made to inclose the whole.

5. For washing (p. 28).—Beaker glasses; glass cylinders; wooden vanning troughs (Fig. 4, p. 29), etc.

6. For weighing.-Brass pincettes with fine ivory points for taking up small weights, metal buttons, etc., and others with blunt or broad points for lifting larger weights and heavier buttons of precious and base metals; brass mixing spoons, 18 centimeters (7.08 inches) long and 2 centimeters (0.78 inch) wide, having on one end a spatula 1.2 centimeters (0.48 inch) wide; camel's hair and bristle brushes; watch-crystals; small glass or porcelain vessels; glass tubes, one end fused shut and the other closed with a cork or glass stopper; glazed paper; artistically closed cornets of fine letter paper of different colors. They are used for the reception of shavings, granules, etc., of alloys, etc.

7. For charging.-Mixing scoops (Figs. 6 and 6a, p. 32); mixing spatula of brass or horn; bristle brushes; measuring spoon for granulated lead; touch stones and touch needles, etc.

B. Implements for transporting the assaying vessels and for manipulating the same in the furnace.-Iron tongs (Fig. 46) for catching hold of the vessels. For large muffle-furnaces they are 80 to 100 centimeters (31.49 to

39.37 inches) long, and, for smaller furnaces, 50 to 60 centimeters (19.68 to 23.62 inches).

Scorification tongs

Fig. 47.

with one arm forked, as shown in Fig. 46a, the horse

Fig. 48.

shoe part just large enough to fit the scorifier, 60 millimeters (2.36 inches) long and 45 millimeters (1.76 inches) wide; crucible tongs (Fig. 47) for wind and blast furnaces. Small assay plates of sheet iron, with handles. They are about 14 centimeters (5.5 inches) square, and are provided with 9 depressions each 28 millimeters (1.1 inches) wide, in which cornets, simple weights of lead (Bleischweren), etc., are kept. The following implements are required for manipulations in the furnace during roasting, fusing, etc.: curved stirring rods and spatulas of iron; iron ladles; tongs with curved tips (Fig. 466) for taking hold of cornets, buttons, etc.; cooling iron (Fig. 48). The blade of this for large muffle-furnaces is 9 centimeters (3.54 inches) long, 7 centimeters (2.75 inches)

wide, and 1 centimeter (0.39 inch) thick. It is provided with a handle 85 centimeters (33.4 inches) long. For small furnaces the respective dimensions are: 5 centimeters (1.96 inches), 4 centimeters (1.57 inches), 0.7 centimeter (0.27 inch), and 70 centimeters (27.55 inches).

C. Implements required for the reception and further treatment of the assay samples after they have been taken from the furnace.

1. For the reception of the assay samples are required; sheet-iron plates with handle. They are divided into squares by strips of sheet iron crossing each other, or have depressions, each about 4 centimeters (1.57 inches) wide, in which the assay vessels are placed; open and closed ingot moulds for casting lead and silver bars, ingots, etc.; small iron or leaden plates (Kornbleche), about 10 centimeters (3.93 inches) long and 60 millimeters (2.36 inches) wide, with depressions 3 centimeters (1.18 inches) wide for the reception of gold and silver buttons from the cupel; and boards of wood with larger depressions for the reception of buttons of base metals.

2. For the further treatment of the samples after they have become cold.-Hammers for breaking the clay crucibles, etc., and removing the slag from the buttons. The body of these is about 9 centimeters (3.54 inches) long, the head square, the other end running into a point (also smaller hammers); an anvil with a plate beneath it about 6 centimeters square (2.36 inches); cupel tongs (pliers), 160 centimeters (63 inches) long, for taking the buttons of silver and gold from the cupels; a button brush consisting of a brass holder with bristles at both ends; a bar magnet for extracting particles of iron from the slag, etc.

VII. Assay Reagents.

22. REAGENTS1 FOR DRY ASSAYS.

According to their action they may be divided into1. Reducing agents.-Charcoal in the form of powder, or of small pieces placed on top of the charge (assays of lead, copper, etc.), or of crucible lining (assays of iron); when it is generally mixed with other reducing agents (potassium carbonate, sodium carbonate, etc.), because the presence of a large percentage of charcoal without additions in smelting processes renders the charge more difficultly fusible.

Powdered coke, anthracite, and graphite may also be used instead of powdered charcoal, but they are less combustible. Rosin, fat oils, tallow, sugar, etc., were formerly also employed. Bitartrate3 of potassium (argol) (KC,H2O), either crude or refined, yields considerable carbon in becoming carbonized, and in consequence exerts a vigorous reducing effect, but causes refractoriness. For this reason its percentage of carbon is reduced, if necessary, by mixing it in different proportions with saltpetre. The mixture is poured into a red-hot crucible, placed under a well-drawing chimney. The mixture deflagrates and emits empyreumatic vapors, when, by reason of a partial oxidation of the carbon, a mixture of potassium carbonate and carbon is formed. This is known as black flux. For vigorous reduction it is made from 1 part of saltpetre and 3 parts of argol; for less vigorous, either of 1 and 2, or 1 and 2 parts respectively. Another flux

1 Muspratt's techn. Chemie, 3d Aufl. Bolley, Handb. der techn. chem. Untersuchungen, 1879.

2 Werthbestimmung in Fresenius' Ztschr. 1875, p. 394.

3 Werthbestimmung in Fresenius' Ztschr. vii. 149.