9 
THE TRENNER-LEE FORMALDEHYD DISINFECTOR. 
This apparatus depends upon the principle of generating the forinal- 
dehyd gas from its watery solution, plus 1 per cent of glycerin, by dis- 
tillation from a retort without pressure. For the purposes of disinfection 
against bacteria 12 ounces of formalin (40 per cent) are prescribed for 
each 1,000 cubic feet of air space. 
Ko. 5. 
This experiment Tvas made in the same room, of 2,000 cubic feet 
capacity, as No. 1, and, as before, no calking or pasting was done. 
Twenty ounces of formalin (40 per cent), with the addition of 1 per cent 
of glycerin, were distilled in the Trenner-Lee apparatus. It required 
about forty -five minutes to evaporate this quantity. The room was 
kept closed six hours. 
The cultures of bacteria were exposed as follows : 
Paper slips impregnated with — 
Garden 
earth. 
Subtilis 
spores. 
Anthrax 
spores. 
Staphy- 
lococcus. 
Pyocya- 
neus. 
Icter- 
oides. 
In envelopes, not sealed 
-f 
-f 
+ 
_ 
_ 
In Petri dishes, open 
-f- 
+ 
— 
— 
I.ost. 
— 
In paper boxes, perforated ends 
+ 
+ 
+ 
-f 
— 
— 
Mosquitoes were exposed as follows : 
Dead. Alive. 
In a battery jar containing crumpled paper and a crumpled towel, loosely 
filling about half the jar (the object was to afford -a hiding place for 
the mosquitoes) 0 12 
In pill boxes — 
Covered with 1 layer toweling 0 5 
Covered with 2 layers toweling 0 6 
Covered with 4 layers toweling 0 4 
Under 2 layers moist tissue paper 0 5 
Wrapped in 4 layers damp toweling 0 8 
Wrapped in 6 layers damp toweling 0 7 
Rolled 4 times in a towel, ends not closed 2 6 
Rolled 10 times in a towel, ends not closed 0 4 
In this experiment the insects succeeded in hiding in tlie remote folds 
of the paper and towel in tlie battery jar, so that they escaped the effects 
of the gas, which was in sufficient strength to kill most of the non-spore- 
bearing organisms. Almost all the insects survived the other conditions 
of this test. Short exposures (six hours) to the ordinary percentages 
are, therefore, not enough to kill mosquitoes with as slight a protection as 
1 layer of a crash towel. 
