286 



Mr. W. H. Preece. 



[Dec. 22, 



I was anxious to see if the shellac flake had any influence on the 

 fusing current: — 



(a.) Shows the effect with shellac. 

 (&.) Without shellac. 



Tin. 



Diameter of wire. 



Current in amperes. 



Fusing 

 current 

 calcu- 

 lated 

 from the 

 formula 



Amperes 



Constant 

 "a" 

 when 

 d ex- 

 pressed 

 in inches. 



In 



inches 



In 



centi- 

 metres. 



Standard 

 wire 

 gauge 

 No. 



Shellac 



flake 

 melted. 



Wire 

 red hot. 

 Visible 

 in air. 



Wire 

 fused. 



o-oio 



-014 

 0-018 

 0-020 

 0-026 

 0-030 

 0-033 

 0-036 



025 

 036 



0-046 



0-051 



0-066 



0-076 



0-084 



0-091 



33 

 28 



26 | 

 25 | 

 22 j 



M 



20 | 



1-931 



3- 181 j 



4- 078 



•4-485 

 6-933 

 9-300 

 11 -380 

 11 -745 



2-413 

 (b) 4-282 

 (&) 5-384 

 {b) 6-812 



(b) 11 -100 

 (5) 13 -703 

 (b) 14-930 

 (b) 17 '620 



2-736 

 (a) 3-630 



5- 058 

 (a) 4-976 



6- 117 

 (a) 6-281 



7- 667 

 (a) 10-443 



12- 154 

 0) 12 -725 



13- 950 

 (a) 14-192 



15 :414 

 (a) 15-908 

 17 -860 



2-760 



} 6-670 



| 7-810 



1 11 -600 



} 14 -350 



1 16-500 



\ 18 -800 

 J 



Mean = 



2730 -7 

 3051 "5 



28S4-8 



2709 -2 



2897^5 



2683-3 



2570 -1 



2575 -2 



2762-8 



Hence it appears that shellac acts as a flux and prevents oxidation. 

 Thus tin fuses at a temperature less than that of luminosity. 



