PRACTICAL DIRECTIONS FOR DISINFECTION. 215 
to the penetration of porous, non-conducting articles, such as rolls of 
blankets, clothing, etc. These points have been the subject of nu- 
merous experimental investigations, and the principles involved 
have been elucidated, especially by the investigations of Esmarch 
(1887), of Budde (1889), and of Teuschner (1890). 
It has been shown that streaming steam is more effective than 
confined steam at the same temperature, because it penetrates porous 
objects more quickly. Also that superheated, “‘ dry” steam is not as 
effective as flowing steam at 100° C.; on the other hand, it corre- 
sponds in effectiveness with dry air, and the temperature must be 
raised to 140° to 150° C. in order to quickly destroy the spores of 
bacilli. 
Esmarch’s investigations show that streaming steam penetrates 
porous objects, like rolled blankets, more readily than confined 
steam; but the later researches of Budde and of Teuschner show 
that a temperature of 100° C. is more rapidly reached in the interior 
of such rolls when the flowing steam is under pressure. With the 
same pressure (fifteen pounds) a temperature of 100° C. was reached 
in two and one-half minutes when the steam was flowing, and in 
eleven minutes by steam at rest (Budde). Intermittent pressure 
was not found by Budde to present any advantages over continuously 
flowing steam ; on the contrary, the time of penetration was longer. 
Teuschner, whose investigations are the most recent, arrives at 
the following conclusions : 
1. Strongly superheated steam is not to be recommended for practical 
disinfection. On the contrary, a slight superheating of the steam, such as 
occurs in the apparatus of Schimmel, is nof objectionable. 
2. Those forms of apparatus in which the steam enters from above are 
much safer and quicker in their disinfecting action than those in which this 
is not the case. In the construction of such apparatus care must be taken, 
in order to secure penetration of the objects, that the air and steam have a 
free escape below. 
3. Disinfection is hastened by previously warming the apparatus. 
4. The most rapid disinfecting action is secured by the use of streaming 
steam in a state of tension (under pressure). 
5. Objects which have been in contact with fatty or oily substances 
require a longer time for disinfection than those which have not. 
6. To accomplish disinfection it is necessary to expel, as completely as 
possible, all air from the objects to be disinfected, and also to secure a suffi- 
cient condensation of the steam. 
7. The condensation of the steam advances in a sharply defined line 
from the periphery to the centre of porous objects. 
8. The temperature necessary for disinfection is only found in the zone 
where condensation has already taken place. 
9. Only a few centimetres from the zone in which the temperature is 
100° C.—when disinfection is incomplete—there may be places in which 
the temperature is 40° C, or more below the boiling point. 
