362 
ME.  CEACE  CALYEET  AND  ME.  E.  JOHNSON  ON  THE  EELATR’E 
and  therefore  we  concluded  that  an  alloy  of  tin  and  copper  containing  68  per  cent,  of 
the  latter  metal,  has  a conducting  power  five  times  less  than  it  should  have  according  to 
theory.  From  the  above  results  it  is  highly  probable  that  these  alloys  of  tin  and  copper, 
and  especially  the  three  last,  are  definite  chemical  compounds ; for  if  they  were  mixtm-es. 
they  would  conduct  heat  in  ratio  to  the  equivalents  of  the  metals  composing  them,  and 
would  not  each  have  a peculiar  and  difierent  conductibility.  These  views  are  substan- 
tiated by  experiments  which  we  have  made  with  square  bars  composed  of  sectional  parts 
of  copper  and  tin.  These  bars  were  made  by  a very  skilful  optician  of  this  town. 
Mr.  Dancee,  and  the  parts  soldered  together  with  tin  solder  in  so  thin  a layer,  that  it 
did  not  occupy  a space  of  0'25  millim.  in  the  five  junctions. 
The  first  two  bars  we  employed  were  of  the  usual  dimensions,  and  composed  of  cubes 
of  copper  and  tin,  each  1 cub.  cent.,  arranged  in  the  following  order: — 
Bar  No.  1 (see  Plate  XXVII.),  2 cubes  of  tin,  2 cubes  of  copper  and  2 cubes  of  tin. 
Bar  No.  2 (see  Plate  XXVII.),  2 cubes  of  copper,  2 cubes  of  tin  and  2 cubes  of  copper. 
The  results  arrived  at  were — 
Foinid 
Calculated. 
Silver 
= 1000. 
(Mean). 
Found. 
Calculated. 
Bar  No.  1 
17- 25 
18- 35 
18-12 
541 
568 
Bar  No.  2 
22-23 
575 
696 
Therefore  these  two  bars  conduct  heat  nearly  as  the  theoretical  results  indicate ; the 
slight  difference  of  1 or  2 degrees  between  the  obtained  and  calculated  figures  being  pro- 
bably due  to  the  influence  of  the  tin  solder  existing  between  each  cube,  and  to  the  cubes 
not  being  perfect  in  all  their  dimensions.  Still,  what  different  results  these  bars  give,  as 
compared  with  alloys  having  nearly  the  same  per-centage  of  tin  and  copper ! for  we  have 
Obtained. 
Calculated. 
Silver 
= 1000. 
Found. 
Calculated. 
Bar  No.  1.  Tin  
Copper... 
62-39  1 
37-21  i 
Conductibility 
17-25 
18-12 
541 
568 
Alloy : — 
1 equivalent  of  Tin 
1 equivalent  of  Copper 
100-00 
65-02' 
34-98  j 
> Conductibility 
13-25 
17-80 
415 
558 
100-00 
Bar  No.  2.  Tin  
Copper... 
29-331 
70-67  J 
> Conductibility 
18-35 
22'2S 
575 
696 
Alloy : — 
1 equivalent  of  Tin 
4 equivalents  of  Copper 
100-00 
31-73' 
68-27, 
^ Conductibility 
4-96 
21-88 
155 
686 
100-00 
- 
