Under the title, Labor-Saving Appliances in the Works-Laboratory, I published a paper in which was described how multi-manipulations in a works-laboratory and in the furnace-room of an assay-laboratory, can be condensed into single manipulations by applying the proper mechanical devices. For example, I now deposit in, or withdraw from, a muffle a set of 48 cupels as one unit. The front row (8) of these are blanks or heaters; the other 40, when they have attained the proper temperature in the muffle, are charged simultaneously with the 40 lead-buttons. Three manipulations here accomplish an operation which by the generally customary method requires 136, and this number is only limited by the size of muffle and cupels. This operation is an enlargement of what I have already described in my former paper, and Fig. 1 shows the improved implements.
In the paper referred to I described a gold-silver bead parting-bath, which is the last of the devices used in regular sequence in practice. This bath was designated as being convenient, but was not a labor-saver properly. Fig. 2 of the present paper shows a new device. Instead of the original tray, there are now sectional holders for the test-tubes, each having a wooden handle on either end, so that the holders may be removed from the boiling bath, and the acid or water poured off from each set of tubes (in this case, 7) without waiting to cool. The tubes, held in place by clutches, as shown in Fig. 3, rest in holes in the base-strip, having a smaller diameter than the tubes. Each holder is stamped at either end with a number, so that the bath becomes further useful by permitting several men to use it at the same time without interference. Apart from the handles, the holders are made of sheet-copper.
The temperature of the parting-bath may be raised above the boiling-point of the water by adding to the latter an adequate quantity of glycerine. Salts (sulphates) are not desirable for this purpose, since they have the tendency to creep over the bath.
Fig. 3 shows also the device by which each set of tubes is filled with wash-water. The supply of water is turned on by means of a pinch-cock, and the glass cocks of the individual outlets are set so as to insure an equal stream from each orifice. When in operation, the whole stands in a drain.
Fig. 4 shows an annealing-cup holder, enabling the operator to transfer the gold in sets from the tubes to the cups. The individual clutches are cut from brass pipe. The cup-holder is placed over the tubes in their holder in such a manner that the mouth of each tube slips into a cup. With a little deftness the two holders are then inverted and left together long enough in that position to permit the gold to settle to the bottom of the cups, when the tubes are withdrawn carefully, so as not to spill any of the gold with the water. The glass rods, fastened to a hinged wooden bar, are then turned down over the tops of the cups, and the water from the latter poured off. Were the whole device constructed of metal, the cups with the gold-contents could be dried and the latter annealed therein; instead, they are now transferred to a special sheet-iron tray with a wooden handle, Fig. 5, dried on a hot-plate and annealed on a gas-stove.
The description of labor-saving appliances given in the original and in this supplementary paper demonstrates that, with the sole exception of weighing, the idea of “ working in sets ” can be carried through every operation in the assay-laboratory and furnace-room.
