The “platinum wire” is an absolutely indispensable adjunct to a blowpipe outfit, and is employed as follows:--A short piece of the wire, an inch or so in length, being attached to a handle, as previously described, the free end of it is bent into a loop about the size of this O. This may be heated in the flame employed, or, better still, in the flame of a spirit lamp, and, when hot enough, it may be dipped into a small quantity of the powdered borax or microcosmic salt, some of which will be found to adhere to the wire. On further heating the borax it will swell out and form a number of irregular bubbles, which (heat still being applied) will subsequently settle down into a clear, colourless bead in the loop of the platinum wire. A satisfactory bead having now been made, a portion of the mineral substance to be analysed (in the shape of small grains) is taken up by dipping the heated borax bead therein. The actual operation of determining the nature of the substance then commences. Using the blowpipe, and directing either the _reducing_ flame (R.F.), or the _oxidising_ flame (O.F.), on to the substance on the borax, according to circumstances presently to be detailed, the operator notes the change in colour (if any) of the flame yielded by the process. At this point a very annoying thing sometimes happens; for, in liquefying the borax bead, it is apt to fall off the wire, and another bead has then to be made. To avoid this, great care should be taken not to blow too vigorously at first. With the microcosmic salt especial care and dexterity must be exercised in this connection. If all goes well, the powdered mineral substance (if fusible in the borax) readily melts down, and becomes incorporated with the borax. On permitting the latter to cool, which it very rapidly does, the bead should now be carefully examined, and any change in tint noted. Most beautiful transparent colours, pregnant with meaning, are often seen to have formed with the borax as flux.