358 
ME.  CEACE  CAL^TIET  AjSD  iVIE.  E.  JOHXSOX  OX  THE  EELATIYE 
the  worse  conductor;  for  example,  alloys  composed  of  ISn  2Cu;  ISn  3Cu;  ISn  4Cu:  in 
this  case  each  alloy  has  its  own  arbitrary  conducting  power ; the  conductibility  of  such 
an  alloy  gradually  increases  and  tends  towards  the  conducting  power  of  the  better  con- 
ductor of  the  two  metals  composing  the  alloy. 
Before  describing  the  experiments  which  relate  to  these  three  classes  of  alloys,  we 
deem  it  advisable  to  state,  that  from  the  numerous  assays  which  we  have  made,  we  are 
led  to  believe  that  the  conduction  of  heat  by  alloys  is  greatly  modified  by  the  ciTstalline 
system  to  which  each  of  the  metals  composiag  them  belongs,  or  by  the  peculiar  crystal- 
line form  of  its  own  crystals ; for  we  have  observed  that  some  of  the  crystallized  alloys 
of  copper  and  tin,  and  copper  and  zinc,  have  a special  conducting  power  of  their  own ; 
for  example,-— 
Found. 
Calculated. 
Silver = 
= 1000. 
Found. 
Calculated. 
Tin  ...  1 equivalent 
Copper,  3 equivalents 
..  38-21  p 
..  61-79/ 
15-75 
21-37 
494 
670 
100-00 
j Tin  ...  1 equivalent 
Copper,  4 equivalents 
1 
..  31-731 
..  68-27/ 
100-00 
4-96 
21-88 
155 
686 
Whilst  the  alloys  which  present  little  or  no  crystallization  have  a conducti’vity  which  is 
in  ratio  to  the  equivalent  quantities  of  the  metals  composing  them ; for  example, — 
Found. 
Calculated. 
Silver = 
= 1000. 
1 
Found, 
Calculated. 
Lead  .. 
Tin  .. 
. 1 equivalent  .. 
. 3 equivalents  .. 
. 36-991 
. 63-01  / 
100-00 
11*96 
11-86 
375 
372 
■ Lead  . 
I Tin  .. 
. 1 equivalent  .. 
. 4 equivalents  .. 
. 30-56 1 
. 69-44/ 
12-17 
12-14 
381 
381 
1 
100-00 
The  method  which  we  have  followed  to  calculate  the  theoretical  conducting  power  of 
our  alloys  is  the  following : — 
Multiply  the  per-centage  quantity  of  each  metal  by  the  respective  conducting  power  of 
that  metal,  add  the  results  together  and  diAdde  by  100  ; for  example,  in  tire  alloy  Pb  3Sn. 
Pb  36-99  X 9-17  = 339-19 
3Sn  63-01x13-45  847-48 
100)1186-67 
11-86  the  theoretical  conducting  power  of  the  alloy. 
We  have  also  taken  care  always  to  cool  the  alloys  rapidly,  so  as  to  render  their  mass 
