a  •    Jour.  Pbarm.  1 
Dec.,  1886.  / 
Number  of  Bacteria  in  Ice. 
603 
The  most  striking  feature  of  the  table  is  the  great  difference  in  the 
individual  results.  This  will  probably  depend  on  the  spot  where 
the  ice  was  formed,  whether  near  or  far  from  the  surface,  and  whether 
near  or  far  from  the  bank.  It  is  further  evident  that  the  quantities 
-of  bacterial  germs  are  sufficient  to  justify  the  question  whether  such 
material  ought  to  be  employed  for  certain  purposes.  Water  contain- 
ing so  many  germs,  at  times  amounting  to  thousands,  would  be  con- 
demned for  purposes  of  common  use.  Moreover,  there  is  reason  to  be- 
lieve that  the  water  corresponding  to  such  ice  is  very  much  worse  than 
the  ice  represents  it  to  be.  The  author  finds  on  counting  the  germs  in 
a  water  and  freezing  the  water,  that  the  corresponding  ice  contains  only 
about  one-fifth  the  number  of  developable  germs.  It  is  evident,  there- 
fore, that  an  ice  rich  in  bacteria  corresponds  to  an  unusable  water. 
.  Figures  are  then  given  showing  the  results  of  experiments  made 
with  ice  from  other  works,  but  as  these  were  known  to  be  from 
more  impure  sources  than  the  ice  already  described,  they  were  not  so 
exhaustively  treated.  The  North  German  Ice-works  also  produce 
ice  from  distilled  and  from  spring  water— far  more  of  the  latter  than 
of  the  former.  Examination  of  the  spring  water  ice  showed  that  it 
also  contained  too  many  bacteria.  The  company  whose  representa- 
tions led  to  this  inquiry  manufacture  about  one-tenth  of  their  supply 
from  spring  water;  the  remainder  from  distilled  water,  distilled  over 
nto  the  freezing  vessel.  The  ice  from  spring  water  was  found  to  be 
as  impure  as  the  other  natural  ice  supplies.  The  following  table 
shows  the  results  of  examination  of  the  ice  made  from  distilled 
water,  and  may  be  usefully  compared  with  the  table  already  given. 
Day  on  which 
Interval 
Number  of  Colonies. 
Plate  Cultivations 
Day  of  Counting. 
in 
Counted  in 
Counted  in 
were  made. 
hours. 
l  ccm. 
Yz  ccm 
14th  April 
% 
18th  April 
90 
10 
6 
0  6 
loth 
19th  " 
90 
0 
2 
3  0 
18th 
u 
21st  " 
70 
14 
3 
3  3 
19th 
22nd  " 
70 
8 
8 
2.5' 
20th 
ci 
23rd  '; 
70 
6 
4 
4  5 
21st 
it 
24th  " 
70 
0 
6 
4  4 
24th 
27th  " 
70 
0 
2 
0  0 
2&th 
li 
1st  May 
70 
0 
0 
3  0 
30th 
3rd  " 
70 
0 
0 
0  0 
1st  Ma 
y 
4th 
70 
12 
4  9 
2nd  " 
5th ,  " 
70 
6 
I 
5  2 
3rd  " 
6th      "  , 
70 
2 
7 
3  5 
4th  " 
7th  " 
70 
3 
3 
2  0 
