POWEE  OF  METALS  AND  ALLOYS  TO  CONDUCT  HEAT. 
353 
a solution  of  protosulphate  of  iron  was  added.  The  gold  thus  precipitated  was  washed 
with  hydrochloric  acid,  and  fused  with  a little  borax  and  nitre. 
Silver. — Pui’e  chloride  was  reduced  by  fusing  with  pure  carbonate  of  potash. 
Copper  was  obtained  by  reducing  piu’e  oxide  of  copper  by  a current  of  pure  hydrogen, 
or  by  depositing  it  from  a solution  of  pure  salt  at  a pole  of  a galvanic  battery. 
Tin. — Well-ciystallized  protochloride  of  tin  was  recrystallized,  and  when  quite  pure, 
was  reduced  by  being  fused  with  a mixture  of  bicarbonate  of  soda  and  lamp-black. 
Bismuth. — Pulverized  bismuth  was  dissolved  in  strong  nitric  acid,  the  liquor  filtered 
through  asbestos,  and  mixed  with  twenty  times  its  bulk  of  water.  The  subnitrate  thus 
obtained  was  washed,  dried,  and  reduced  with  lamp-black. 
Antimony. — This  metal  was  pulverized  and  fused  with  a mixture  of  pure  nitrate  and 
carbonate  of  soda ; the  antimoniate  of  soda  so  produced  was  washed  with  boiling  water 
until  the  filtrate  was  no  longer  alkaline.  The  insoluble  mass  was  dried  and  reduced 
with  lamp-black. 
Lead. — Nitrate  of  lead  was  recrystalhzed,  and  when  pure,  the  salt  was  dried  and 
calcined.  The  oxide  of  lead  so  prepared  was  reduced  by  lamp-black. 
Zinc. — Vieille  Montague  zinc  was  redistilled  twice. 
Cadmium. — This  metal  was  obtained  pm’e  by  dissolving  in  hydrochloric  acid,  and 
passing  sulphm’etted  hydrogen  into  the  liquor.  The  sulphuret  of  cadmium  was  well 
washed  with  a solution  of  sulphuretted  hydrogen  and  dissolved  in  hydrochloric  acid; 
carbonate  of  ammonia  was  added,  and  the  precipitate  was  washed,  dried,  mixed  with 
lamp-black,  and  the  cadmium  distilled. 
The  platinum,  aluminium,  iron  and  sodium  which  we  used,  were  only  commercially 
pure. 
As  the  determination  of  the  power  of  metals  to  conduct  is  of  great  importance,  we  shall 
give  here  a detailed  record  of  the  results  obtained : — 
Name  of  the  metals. 
Temperature 
of  the 
50  cub.  cent,  of 
water  before 
Temperature 
of  the 
50  cub.  cent, 
after 
Conductibility 
found. 
Mean. 
Conductibility. 
Silver  =1000. 
beginning. 
15  minutes. 
Silver 
10  0 0 
10  0 0 
Gold 
lOOU 
GoldjS^. 
Copper  (rolled) 
Copper  (cast) 
Mercury  
Aluminium  ... 
ri9-8 
119-7 
h4 
\ 13-6 
r20-3 
20-3 
h20*0 
r 19-5 
j 20-0 
) 21-0 
1^20-5 
f 21-30 
\ 21-45 
/15-0 
\l6-6 
r 18-2 
117-7 
51-6 
51-7 
45- 4 
44-8 
47-3 
47-0 
46- 7 
46- 3 
47- 1 
48- 0 
47-45 
47-2 
47-3 
36-7 
38- 1 
39- 3 
39-0 
31- 8  1 
32- 0  / 
31-40  1 
31-20  / 
27-0  ^ 
26-7  > 
26- 7  J 
26-8  1 
27- 1  I 
27-0  f 
26-95  J 
25-90  \ 
25-83  / 
21-7  1 
21-5  / 
21-1  1 
21-3  / 
31-9 
31-30 
26-80 
26-95 
25-87 
21-60 
21-20 
1000 
981 
840 
845 
811 
677 
665 
3 B 2 
