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Arrangement and course of the experiment. 



If a mixture of sulfur and chalk is introduced into a saltpetre solution with 

 addition of some garden soil or canal mud, there will soon evolve at room tem- 

 perature or at 25 to 30 C., a current of gas consisting of free nitrogen and 

 carbonic acid. Thereby the saltpetre is denitrified, the sulfur is oxidised to sul- 

 furic acid, found back as gypsum and potassiumsulfate, after the formula. 



6 KNOa + 5S + 2 CaCOs = 3 K 2 SOi + 2 CaSOi + 2 COa + 3Na 



whereby per gram of decomposed nitrate about i cal. is produced. When after 

 some days the process has become intense, the mud with the gas rises to the 

 surface, and if the experiment is carried out in a flask, the contents can flow out with 

 the gas as a slimy mass. This is bacterial slime, which keeps the sediment together. 



If using distilled water with 10% chalk, io/o sulfur, 2 o potassiumsaltpetre, 

 o,02/o bipotassium phosphate, o,O2/o magnesium chloride, and infecting with a 

 small floccule from the said denitrification, we see after some days at 25 to 30 C. 

 the very same phenomena as when using soil, only less intense; so the presence 

 of soil is not necessary, but is clearly acts favourably. If the soil or mud is 

 beforehand left a few days under a dilute saltpetre solution, so that all the or- 

 ganic substances fit for denitrification are removed, the soil remains quite as 

 good for the sulfur-chalk experiment, hence the organic matter cannot be the 

 cause of the favourable action on the process. It seems to result from the 

 presence in the soil of colloidal silicic acid and aluminium silicate, which are to 

 be considered as catalyzers that hasten the decomposition. So, in a thiosulfate 

 denitrification the reaction goes on much swifter in presence of chalk and bolus 

 (aluminium silicate) than with chalk only. 



The saltpetre solution can be used in the most different concentrations. Even 

 in io"/o solutions in tapwater made to a pap with sulfur and chalk, I saw at 

 room temperature a spontaneous, intense gas production, with slime formation. 

 The gas was nitrogen and carbonic acid ; nitrogen oxydul seemed quite absent. 

 The slime is bacterial slime, for the greater part consisting of different varieties 

 of Bacterium stutzeri and B. denitrificans. It is so voluminous that its formation 

 can only be explained by admitting that the said bacteria themselves produce 

 this slime from the carbonic acid by chemosynthesis. With distilled water the 

 result of the experiment is the same. In a closed bottle and with destilled water 

 the process goes on as with accession of air, which proves convincingly, that 

 presence of organic substance is not required for the development of the rich 

 bacterial flora which encloses the chalk and sulfur, and where at last many in- 

 fusoria and monads, that feed on the bacteria, may be observed. As said the 

 organic matter of the bacterial bodies must here be formed from the carbonic 

 acid, whilst the required chemical energy is produced by the oxydation of the sulfur. 

 Consequently this is a case of chemosynthesis and no other analogous process is 

 known which produces organic substance in a simpler and more profuse way 1 ). 



') It is true that chemosynthesis at the oxidation of hydrogen in presence of 

 carbonic acid and soil, described by Niklewsky and Lebedcff, is as productive in 

 organic substance, but the experiment is less simple. 



