THE PRODUCTION OF SULPHURETTED HYDROGEN ^^ 



Thus sulphur is produced and energy hberatcd. The 

 following reactions then take place : — 



(11) 



CH„ . S . H CH, - S . S . - CH., 



I " I " I " 



2CH . NH, + H2CO3 = CH . NH„ CH . NH., + H . CHO + H„0, 



I 1 " I " 



c=o c=o c=o 



I I I 



R R R 



(III) H2O, = H20+i02 



Thus oxygen is developed inside the cell, which is utilized 

 to oxidize the sulphur to the sulphate, 



S— + 20^= SO4— . 

 The conclusions of this worker cannot be taken as final, for 

 all the pieces do not " fit." Thus sulphuretted hydrogen is 

 more soluble in an alkaline than in an acid medium, and yet 

 in the table given above an increasing alkalinity (H"^ from 

 I0~^ to I0~^) is associated with a decrease in the amount 

 of HgS in solution (from 2-2 X lO"^ to 2-2 X lO"^). Again, 

 Baas-Becking insists on the absence of organic matter from the 

 beds in which the sulphur bacteria are developing, and the use- 

 lessness of such matter in the metabolism of these organisms. 

 Under natural conditions the reactions which according to 

 him take place in the sulphur metabolism could not occur 

 except in the presence of an ample supply of organic matter : 

 for all of them are the direct results of the decomposition of 

 organic matter through the agency of saprophytic and other 

 microorganisms. Finally, the beneficial effect of supplying 

 the sulphur bacteria with a fluid containing sulphuretted hydro- 

 gen in solution is well established, and it is proved that the 

 organisms assimilate this substance directly in their metabol- 

 ism ; and this in spite of the fact that the energy level of 

 hydrogen sulphide is below that of sulphur. The sulphur 

 appears to be excreted and oxidized to sulphate outside the 

 cell. There is no reason to suppose that the sulphur takes 

 further part in metabolism any more than it does in the 

 metabolism of the thionic acid bacteria which deposit the 

 sulphur outside, instead of inside the cell. 



3 



