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iiig the organisms are placed between the fold of the sterile blankets or 
j sheets. The rule was to allow the blankets and sheets to dry. Some- 
times they were used while still moist, but when this latter was done it 
is always specifically noted. 
Three methods were adopted in placing the formalin in the boxes : 1, 
sprinkling ; 2, pouring ; 3, soaking on absorbent cotton. 
Particular pains were taken in sprinkling because it was found that 
the result depends upon the technique of sprinkling. 
The formalin was sprinkled from a pipette, drawn out so as to deliver 
a small drop. The solution was dropped from the pipette upon the 
blankets or sheets, as the case may be, spread out on the bottom of the 
box. The drops were evenly distributed over the surface and sufficiently 
far apart so as not to run together. It makes considerable difference in 
the results whether the formalin is poured on one place or carefully 
sprinkled in the manner indicated. 
The time of exposure varied from twenty -four hours to five days, and 
is stated for each test. The boxes were ordinary pine packing cases, 
made reasonably gas tight by the use of impervious paper and varnish. 
They closely imitated the conditions presented by a trunk. In all other 
respects the experiments were made to imitate as closely as possible 
s the conditions found in packing the average trunk. 
I' / After charging the boxes the covers were nailed down and left at the 
. room temperature, which in this laboratory is about 18° to 25° C. When 
the time of exposure has expired the boxes are opened and the slips of 
paper are inoculated into bouillon without delay. The large size test 
tubes, two-thirds full of bouillon, were used in order to dilute the trace 
of formaldehyd which sometimes remains. The method of neutralizing 
the slips of paper after exposure to formaldehyd with ammonia before 
inoculating them into bouillon was not used in all cases, especially in 
the earlier parts of the work. From and including test No. 39 all the 
slips were neutralized as follows : 
After the exj^osure the slips are held fifteen to thirty seconds in a beaker 
containing ammonia and then planted in bouillon. It is well to wash out 
the formamide formed by the combination of the formaldehyd and 
ammonia with a little distilled and sterile water, but that this is not 
necessary is shown in the following test : 
Slips of filter paper impregnated with bouillon cultures of typhoid, 
anthrax, and diphtheria, prepared as described above, were placed in a 
petri dish and exposed to formaldehyd for ten minutes by placing a 
little pledget of cotton containing a few drops of formalin in the same 
dish. Some of the slips were then inoculated into bouillon with the 
, following result : 
T 3 q)hoid (3 slips), no growth. 
Anthrax (3 slips), all grew. 
Diphtheria (3 slips), no growth. 
