wBm — 
Dried tuberculous sputum under different conditions — -Continued. 
Author. 
Conditions. 
Not killed. 
Killed. 
■ — j 
Hill 1903 
Tuberculous sputum exposed on glass 
rods in drying box to diffused daylight 
and slow diffusion ol air. 
/Tuberculous sputum spread on glass, ex- 
\ posed to air and light. 
16 days. 
4 days. 
6 days. 
10 days. 
|2 days 
<1 da3 T s 
f 6 days 
Tuberculous sputum in thick layers dried 
14 days. 
Txvjtchpll IQO.n 
on marble slab. 
Tuberculous sputum 
Produced le- 
No lesion after: 
In paraffined bottles in dark moist 
sions at end 
of: 
170 days. . . 
188 dajxs. 
i 
box. 
In paraffined bottles in dark closet... . 
160 daj^s. . . 
188 days. 
In paraffined bottles in diffused light. 
124 days... 
175 days. 
In paraffined bottles in thermostat . . . 
33 days 
100 days. 
Cotton stoppered bottles, in dark 
157 daj 7 s... 
172 days. 
moist box. 
Cotton stoppered bottles, in dark 
100 days. . . 
141 days. 
closet. 
On ice 
102 days... 
153 days. 
On handkerchief 
70 days . . . 
110 days. 
On towel 
70 days 
1 10 days. 
On carpet 
39 days 
70 da3^s. 
In sand, in moist light place 
123 days. . . 
148 days. 
In sand, in drv light place 
30 daj T s. . . 
70 days. 
In open bottles, out doors, winter 
110 days.. . 
132 days. 
Snrmnni. 1900 
Dried tuberculous excretion at 35°C 
15 days 
Rickards, Slack, and Arms, 
Dried tuberculous sputum in tenement 
1908. 
house: 
(a) Sunlight and dry 
( b ) Diffused light and drv 
(c) Dark and dry 
( d ) Dark and damp basement 
Experimen ts 
under way. 
1 month 
85 days 
Experimen ts 
under way. 
THE EFFECT OF SUNLIGHT. 
t 
Koch’s dictum that direct sunlight kills the tubercle bacillus within 
a few minutes to several hours has been confirmed by all workers 
except Feltz. The time required depends upon the brightness of the 
ray, the time of the year, the latitude, the temperature, the thick- 
ness and opacity of the layers, the medium in which the bacilli are 
embedded, and other conditions. 
This action of light corresponds to the well-known germicidal power 
of the ultra violet rays of the spectrum upon other nonspore-bearing' 
bacteria, and must play an important role in diminishing the danger 
from tuberculous sputum and dust out of doors and in sunny rooms. 
7987— Bull. 57—09 3 
