60 



CAPT. LL. LLOYD. 



indicated in the case of 2*5 per cent., they occurred occasionally also in the case of 5 

 per cent, and I'd per cent, strengths. This method confirms the conclusion that the 

 most effective strength to use is 5 per cent., then 7 '5 per cent., then 10 per cent., while 

 2'5 per cent, is the least effective. The factors of effect of these concentrations had 

 been found to be 80 '3, 76"], 62 '5, and 33 '5 respectively. 



Table XIV. 

 Showing the Death-rate of Flies exposed to various strengths of Forjnaldehyde. 



Formaldehyde 



strength 



No. of 

 tests 



Av. no. 

 flies 



Av. percentages inert after 



10% 



7-5% 

 5-0O/O 

 2-5% 



81 

 92 

 98 

 96 



1 hour 



3 hours 



4 hours 



5 hours 



33 



45 



54 



58 



44 



53 



63 



65 



51 



58 



64 



72 



42 



48 



57 



53 



24 hrs 



92 

 93 



96 

 89 



100 r 



90 



60 



70 



<0 

 (D 60 



°50 

 <o 



-^40 

 % 



^ 30 



20 



JO 











\ 









1 ■ 















ff^^ 



.^^ 



*^ 



^^ 





^ 



^ 



^ 

 .«»" 



it*' ., 













^ 



^ 





ar^ 



^^ 



^^ 



c*^ 



.^ 



.^ 



**^ 





, ^ 



^,^ 



, 4^ 



















/i 



A 



.s^ 



a=* 



r^ 





-^ '* 





-• 



^' 



























y 



1/ 





• 



*•* 



^ * 



*^' 



**' 



































A 



7^ 



ri 















































,y' 



' 











































1 



••* 















































p 

















































k 















































































































































12 3 4-5 



6 7 8 9 10 II 12 13 \^ 15 16 17 18 19 20 21 22 23 24 

 Jnteri/a/s oft/me in hours. 



Formaldehyde 10 % 



~=.x«^ „ 7-5 % 

 „ 5-0 % 



„ 2-5% 



Diagram 3. Showing the relative strengths of formaldehyde. 



