74 



THB 8ALTON SEA. 



place of free oxygen. According to Omelianski, * Beggiatoa is dependent upon the action of 

 Spmlhi7n desulphuricaTis (which reduces the sulphates of mineral waters and liberates the 

 hydrogen sulphide that serves the Beggiatoa for food supply), and the hydrogen sulphide is 

 acted upon by an organism that oxidizes it and forms sulphuric acid. It was found that 

 this acid acted upon iron and formed ferrous sulphide which dropped to the bottom of all 

 of the carboys in considerable quantities as the foregoing processes proceeded in the car- 

 boys of Salton Sea water. Chemical analyses of water from the various carboys were secured 

 through the kindness of Dr. Julius StiegUtz, of the Department of Chemistry of the Uni- 

 versity of Chicago. (Table 25.) Carboys (A) and (B) contained Salton Sea water, while 

 carboys (C), (D), and (E) contained Salton Sea water into which specimens of Prosopis 

 glandulosa, Prosopis pubescens, and Larrea iridentata respectively had been placed six months 

 previously. 



Tabu; 25. — Atudyses of water of SaUon Sea, in grams per 100,000 ex. 



In the waters which contained an appreciable quantity of hydrogen sulphide there 

 was a decided decrease in the amount of sulphate ion, showing that the SO4 had been 

 reduced. From the chemical analyses it is shown that every 100,000 of the parts of the 

 Salton Sea water contain from 105.233 to 107.650 parts of sulphate ion before receiving 

 the different woods. After retaining the wood specimens for six months the amount of 

 sulphuric (SO4) varied from 105.800 in Larrea tridentata to 75.39 parts in the culture of 

 Prosopis glandulosa. It was necessary to determine whether or not these changes might 

 have resulted from the direct action of substances in the water. 



According to the work of Beijerinck ^ this reduction of sulphates may have been accom- 

 plished by micro-organisms. One of the prominent anaerobic forms is Spirillum desul- 

 phuricans. He later* discovered forms that were less definitely anaerobic, which were 

 able to aid in sulphate reduction. The final products of this bacterial action include 

 sulphureted hydrogen as one of the main constituents. Thus we have an explanation of 

 the large quantities of hydrogen sulphide that appeared in the cultures of Prosopis and 

 Larrea in Salton Sea water. There were similar but less pronounced results in the cul- 

 tures of these same woods in Lake Michigan water, and similarly the same when Robinia 

 pseudacacia was placed in Salton Sea water and Lake Michigan water cultures. 



The next modification in the chemical change of the output of these first bacterial 

 forms is caused by Beggiatoa, according to Winogradsky.* This organism uses the hydrogen 

 sulphide as a source of energy releasal. The hydrogen sulphide is oxidized to sulphuric 

 acid, and free sulphiu- is first stored in the cell and then liberated in a free condition. The 

 sulphuric acid acts upon the carbonates or some of the bases, as iron, and forms sulphates 

 and ferrous sulphide. This accounts for the large amounts of free sulphur which collected 

 in the bottom of all of the culture carboys of Salton Sea water. It also explains why con- 

 siderable ferroiis sulphide collected in the bottom of the vessel in which the greatest amount 

 of sulphuric was decomposed, i.e., Prosopis glandulosa, where the 105.233 parts per 100,000 

 of Salton Sea water were reduced to 75.39 parts after the H2S was largely oxidized. 



» Omelianski, W., (1) Centralbl. f. Bakt. 2 Abt., vol. vin, p. 193, 1902; (2) vol. xi, p. 369, 1904; (3) vol. xii, 



p. 33, 1904. 

 ' Beijerinck: Centrbl. Bakt., vol. ii, 1, p. 1, 1895. ' Beijerinck: Centrbl. Bakt., vol. ii, p. 193, 1895. 

 * Winogradsky: Ueber Schwefelbacterien, Bot. Ztg., vol. liv, p. 493, 1887. 



