Potash. Sulfur 293 



the carbonate of potash found in wood-ashes, exert the 

 same effect. The carbonate of potash is doubly effec- 

 tive because of its potash and its ability to neutralize 

 acid substances in the soil. In the so-called alkali soils, 

 and, in general, in irrigated districts, the accumulation 

 in the surface soil of salts of potash and of soda, undoubt- 

 edly produces interesting bacteriological effects. 



BACTERIA IN RELATION TO SULFUR 



Sulfur is one of the chemical elements that enter 

 into the composition of protein substances; it is, there- 

 fore, essential to the life of plants and of animals. As 

 one of the indispensable building materials for organ- 

 ized life, it affects the development of bacteria. It is, 

 in its turn, affected by the growth of the latter in its 

 relation to other elements. Locked up in the inert 

 residues of plants and animals, it needs the transforming 

 touch of microorganisms before it can again enter into 

 circulation to be used once more as building material 

 for new cells. 



Sulfuretted hydrogen. — The odor of sulfuretted hydro- 

 gen, a compound of hydrogen and sulfur, is often per- 

 ceptible in the decay of eggs or meat. It denotes, under 

 such circumstances, that certain of the decay bacteria 

 are actively multiplying in the material undergoing 

 decomposition. More frequently, however, the sulfu- 

 retted hydrogen is formed slowly and its odor does not 

 become perceptible. This is true of decay processes 

 in the soil, in streams, lakes and the sea, where the or- 

 ganic debris is broken down by bacteria. But whether 



