SOLDERING. TRANSFERRING LIQUIDS. 



piece of wood and then poured out upon a flat horizontal surface, 

 such as an old plank or a flat stone, that it may form a thin cake 

 from which small pieces may be cut with a strong knife or a pair 

 of cutting pliers. It is better to pour the liquid solder from a 

 height of about l m in a small stream into a pailful of water, which 

 is at the same time stirred with a rod or a bundle of twigs ; the 

 solder is then obtained in a granulated state, thus saving the 

 trouble of further dividing the mass afterwards. 



Metals only adhere to each other if they mutually present bright 

 surfaces. Hence a piece of metal heated for the purpose of sol- 

 dering does not take the solder or as it is termed, the solder does 

 not run unless the metal is treated with a liquid which dissolves 

 the layer of oxide which usually covers the surface. A solution of 

 chloride of zinc, or ' soldering water,' serves best for this purpose. 

 Into a glass capable of containing about 250 CC (nearly 8 ounces) 

 of water, pour 50 grammes of crude commercial hydrochloric acid, 

 and gradually add chippings of zinc, which may be obtained from 

 a tin-smith. At first a brisk effervescence will accompany the 

 solution of the zinc, but afterwards it proceeds more slowly. Add 

 more zinc until some of it remains un dissolved even after a few 

 hours. Then add to the solution 10 grammes of powdered sal 

 ammoniac, which is quickly dissolved if the liquid is stirred. 

 Let the whole stand quiet for some time, and pour off the clear 

 liquid into a small bottle for use. 



When a liquid is to be transferred from one vessel into another, 

 it can be prevented from running down 

 outside of the vessel, by slightly greasing 

 the lip and pouring it down a rod which 

 is placed against the edge in the manner 

 represented in fig. 32. 



By making the solution at once in a 

 larger bottle the necessity of transferring 

 it from one vessel into another may be 

 avoided. The zino must in that case be 

 cut up fine to make it pass through the 

 narrow neck of the bottle, and care 

 should be taken not to bring a flame 

 near the mouth of the bottle as long as 

 the solution is effervescing; the -gas 

 which issues forms an explosive mixture 

 with air, which if lighted would perhaps 

 detonate loudly and destroy the bottle. 

 No dangerous explosion can take place if the solution is made in 



FIG. 32 (-| real size). 



