Electrically  Prepared  Colloidal  Solutions.  411 
•electro -negative,  non  -  oxidizable  metals  give  negatively 
charged  particles.  When  we  recall  that  the  iron  in  such 
solution  appears  to  form  the  hydrate,  and  that  they  bear  a 
charge  of  the  same  sign  as  the  particles  in  chemically  prepared 
colloidal  solution  of  ferric  hydrate,  one  is  justified  in  sus- 
pecting that  in  the  cases  of  iron,  bismuth,  and  lead  there  is 
the  formation  of  the  hydrates,  in  greater  or  less  degree,  in 
the  preparation  of  these  electrically  prepared  solutions.  8uch 
an  hypothesis  at  once  suggests  an  analogous  action  on  the  part 
of  gold,  silver,  and  platinum,  viz.,  an  interaction  between  the 
metal  and  hydrogen — a  view  to  which  the  already  known 
•existence  of  a  hydride  of  platinum  would  lend  some  colour. 
VIII.    Colloidal  Solutions  in  other  Liquids. 
The  suggestions  given  by  the  results  for  the  hydrosols  are 
strengthened  by  the  observations  on  colloidal  solutions  in  the 
alcohols.  Pure  methyl  alcohol  and  pure  ethyl  alcohol  were 
used  in  the  preparation  instead  of  water. 
Although  repeated  trials  were  made  with  the  metals  gold, 
silver,  and  platinum,  the  writer  has  never  succeeded  in  getting 
them  to  remain  suspended  in  either  of  these  alcohols.  On 
the  other  hand,  the  metals  lead,  tin,  and  zinc  form  solutions 
in  both  of  the  alcohols,  while  with  methyl  alcohol  solutions 
were  also  obtained  with  bismuth,  iron,  and  copper.  In  all 
these  solutions  the  particles  moved  to  the  negative  electrode 
in  an  electric  field,  i.  e.,  they  are  positively  charged.  The 
numbers  are  given  in  Tables  V.  and  VI. 
Table  V.— 
Methyl  Alcohol  (free  from  acetone). 
Metal. 
L'sed  in  Pj 
-eparation. 
Specific           Sign  of        Velocity  m 
Conductivity    Charge  on     cms.  per  sec. 
1  of  Solution:      Particles.      per  volt  per 
cm. 
Voltage. 
Current. 
Lead  
30  volts. 
6*5  amp. 
i  10-0  XlO-15            4-             22xl0"5 
Bismuth... 
30      .. 
•j 
!  14-3  xlO-6           +        ;  10-2  xl0~5 
Iron    
40      „ 
,, 
9-oxio-'3  ;      +      h 
Copper   ... 
Tin 
40      „ 
30      „ 
•< 
68  XlO-6            4-               motion 
)■     very 
12VX10-  ;         +               slight 
Zinc    
30      „ 
" 
7-oxio-,!  '      +      ; 
Phil.  Mag.  Vol.  11.  No.  64.  April  1906. 
■1  G 
