142 DISINFECTION— STERILIZATION— DISINFECTANTS 



are the Pasteur-Chamberland (Fig. 105) and the Berkefeld. 

 The former are made of unglazed porcelain of different 

 degrees of fineness, the latter of diatomaeeous earth (Fig. 

 106). The designs of complete apparatus are numerous. 



8. Burying. — This is a time-honored method of disposing 

 of infected material of all kinds and at first thought might 

 not be considered a means of disinfection. As a matter of 

 fact, under favorable conditions it is an excellent method. 



Fig. 105. — Pasteur-Chamberland filter candles about one-half natural size. 



The infected material is removed. Pathogenic organisms 

 tend to die out in the soil owing to an unfavorable environ- 

 ment as to temperature and food supply, competition with 

 natural soil organisms for what food there is, and the injuri- 

 ous effects of the products of these organisms. Care must 

 be taken that the burial is done in such a way that the surface 

 soil is not contaminated either directly or by material brought 

 up from below by digging or burrowing animals, insects, 



