SOLDERS FOR COPPER AND BRASS. 203 



hangs them on a peg, and draws the whole of them straight, to fit 

 their other ends to another peg : in doing which, if he finds the in- 

 testines too short, he makes a hole in their ends, and threads into 

 them short pieces, till the whole is long enough to reach the other 

 peg, placed at a given distance from the tirst. These ends are 

 then affixed to a piece of tape, and fastened to the peg. This 

 done, he applies them to the twisting-wheel, rubbing the cord well 

 between his finger and thumb throughout its whole length, at every 

 turn of the wheel, in order to make it of an equal size. When 

 about half-dry, they are exposed twice to the fumes of sulphur ; 

 after each time, the cord must be well stretched and moistened 

 with plenty of the solution of potash, at the same rubbing with the 

 hair-rubber. It is then left to dry, and afterward cut, and coiled 

 up for sale. 



Catgut for Clock-makers, 



This kind must be very fine ; and of course requires the smallest 

 intestines, well prepared with potash. Sometimes they are made 

 by cutting, with a particular kind of knife, the intestine into two 

 strips. The knife, which is fixed to a table, has two edges, in op- 

 posite directions; and above them, a ball of lead, which is intro- 

 duced into one end of the intestine ; and by drawing the latter con- 

 tinually over the ball, the projecting blades cut it into two strips, 

 which the workman holds, one in each hand ; drawing them regu- 

 larly, till it be cut quite through. 



Watch and Clock-makers also use catgut of various sizes, con- 

 sisting of more than one intestine, and made like the musical-in- 

 strument cords ; which we shall next describe. 

 [To be concluded hi our next.] 



HARD AND SOFT SOLDERS FOR COPPER AND BRASS. 



Solders for Copper. — There are two kinds of these solders 5 

 the one for hard, the other for soft soldering. The hard solder is 

 made with eiglit parts of copper and one of zinc, the copper be- 

 ing tirst melted in a crucible, during which operation, the zinc is 

 also heated. When the copper is melted, the zinc is thrown hot 

 into it : the crucible is then covered, and the whole well shaken 

 together. In about two minutes, the metal is poured out, through 

 the twigs of a birch-broom placed over a proper vessel filled with 

 water. The metal is, by this process, divided into small grains ; 

 after which, it is well washed, and kept for use. This solder is 

 very fusible, and at the same time malleable. 



An alloy, composed of three parts of copper and one of zinc, 

 also makes a good solder. 



In general, the solder is harder or softer, in proportion to the 

 quantity of copper employed. The more copper is used, the hard- 

 er is the solder, but less fusible. The highest degree of hardness 

 is produced when ton parts of copper are united with one part 

 zinc ; but this is also the least fusible. Solders of difTerent de- 

 grees of fusibility are often required, particularly in cases wher» 



