Platinum crucibles and wires may be soldered by means of fine gold wire in the oxyhydrogen jet. It can also be soldered over a blow-pipe. The solder used is auric chloride (Au Cl), which on heating decomposes first into aurous chloride, and at a higher temperature into chloride and gold. The salt melts at about 200 degrees Cent., and in the blow-pipe the gold runs as a solder. Care should be taken to draw the platinum from the flame when the gold is seen to run, in case it spreads too far and leaves the joint weak. The latter must not afterwards be exposed to a higher temperature than that at which the soldering was effected. In the case of soldered-up longish holes, a spongy platinum may be mixed with the auric acid. Hammering the soldered joint while hot serves to finish off the joint. Wires and strips of platinum can in this way be joined by putting the chloride crystals on each clean surface and gently heating them till nearly black, then binding the surfaces together and further heating them in the blow-pipe fire.