18 
In his original work, Walter (41) calls attention to the misunder- 
standing arising from 'the improper use of the terms formaldehyde 
and formalin. Aronson, Trillat, and most investigators used formal- 
dehyde solutions; Oehmichen used formalin. The author also uses as 
a basis formalin (40 per cent formaldehyde solution). 
Treated nutrient gelatin with different amounts of formalin, inocu- 
lated with broth cultures, made Esmarch roll tubes, and observed after 
a week: 
Concentration. 
Anthrax 
spores. 
Cholera. 
Typhoid. 
Staphylo- 
coccus 
pyogenes 
aureus. 
Diphthe- 
ria. 
1:10,000 and greater 
' 
1:20,000 
+ 
+ 
+ 
-f 
-t 
1:50,000 and 1:100,000... 
+ + 
+ + ‘ 
+ + 
+ H- 
+ -F 
Control 
+ + 
+ + 
+ + 
+ + 
+ + 
— = no growth. + = small growth. ++ = rich growth. 
To test the bactericidal power he made up formalin solutions of 
various strengths in flasks, added to each agar cultures of germs, 
shook well, and added the mixtures to fluid gelatin from which roll 
tubes were made after certain exposures. He says that the antisep- 
tic action of what formalin remained after dilution in gelatin was 
negligible. 
SUMMARY OF RESULTS. 
Staphylococcus pyogenes aureus, 
1:2,000, growth after 2 hours’ exposure, liquefaction after If hours to half a minute. 
1:1,000, growth after 2 hours, liquefaction after 1 hour and less. 
1:100, no growth after 45 minutes, growth after 30 minutes, liquefaction after 10 
minutes. 
3:100, no growth after 2 minutes, growth after 1 minute. 
Streptococcus pyogenes. 
1:2,000, no growth after 1|- hours, growth after 1 hour and less. 
1:1,000, no growth after 20 minutes, growth after 15 minutes. 
1 : 100, no growth after 1 minute, growth after | minute. - 
Anthrax spores {dried on silk threads). 
1:2,000, growth after 2 hours, liquefaction after 1 hour and less. 
1:1,000, growth after 2 hours, liquefaction after 2 minutes and less. 
1:100, no growth after 30 minutes, growth after 20 minutes, liquefaction after 5 
minutes and less. 
3:100, no growth after 15 minutes, growth after 10 minutes, liquefaction after 5 
minutes and less. 
B. typhosus. 
1:1,000, no growth after If hours, growth after IJ hours and less. 
1:100, no growth after 20 minutes, growth after 15 minutes and less. 
3:100, no growth after 1 minute, growth after ^ minute. 
