Laboratory Arts 



Three-strand wires are opened against each other, as in Fig. 44, 

 and the wires of one cable inserted in the spaces between the wires 

 of the other cable ; all the wires are then clasped round each other, 



and twisted as nearly as 

 possible into the original 

 diameter of the cable, the 

 projecting ends being re- 

 moved by cutting pliers. 



Seven- and nineteen- 

 strand cables are similarly 

 FIG. 44. treated, but the centre 



strand is removed first, up 



to the point where the untwisting commenced. Joints at an angle, 

 in multistrand cables, are made by pushing the wires of the joining 

 cable through the centre of the continuous one (Fig. 45), and wrap- 

 ping half the projecting strands round the outside of the continuous 

 cable in one direction, the other half in the opposite direction. 



A "Flexible lead" should have a portion of its insulation 

 removed, and have all its strands soldered into one solid wire 

 before it takes part in any joint, save where it can be pushed 

 through a multistrand cable, as above. 



Mere contact of wires should not be regarded as sufficient. 



1 



FIG. 45. 



Joints should be made so as to withstand harsh treatment, and in 

 order to secure strength, and metallic contact throughout, it is 

 necessary to solder all joints. In soldering, however, a flux is 

 necessary, in order to enable the melted solder to flow easily into 

 the joint, and this flux must be of a non-corrosive nature, so that it 

 necessary it may be left in the joint. The solution of zinc chloride 

 recommended for use when "tinning" the soldering bit would not 

 be suitable in these cases, as it is corrosive, and not easily removed 

 save by much washing in hot water, a method not permitted in 



