Chemical Papers. 59 



centage ; and second, the decomposition of the sulfides by atmos- 

 pheric carbon dioxide throwing out the calcium as calcium carbonate, 

 and thus tending to decrease the percentage. 



In the fourth column may be seen the percentages of total sulfur. 

 After the second day this percentage remains practically constant, 

 varying only 0.03 per cent. As with calcium, there are several 

 changes affecting these figures: First, concentration, tending to 

 increase the percentage ; second, decomposition of sulfides by car- 

 bon dioxide in the air forming, (a) in the case of poly sulfides, 

 volatile hydrogen sulfide and insoluble sulfur, and, (h) in the case 

 of monosulfides, volatile hydrogen sulfide only, tending to decrease 

 the percentage ; and third, oxidation to polysulfides and thiosul- 

 fates, thereby throwing sulfur out of solution. These three agen- 

 cies, and perhaps others acting in the same and different directions, 

 produce equilibrium in the percentage. 



If there were sulfites or sulfates present, we would expect a fur- 

 ther decrease in percentage total sulfur, owing to the throwing of 

 sulfur out of solution according to the reactions, 



OaS203 = CaSOs + S, and 

 CaSOa -t- O = CaS04. 



A study of table II will reveal some other interesting facts. 

 The columns representing calcium and sulfur calculated from the 

 percentage of calcium thiosulfate of course show the same rate of 

 increase as the thiosulfate column in table I. 



The column giving percentages of calcium in sulfates shows a 

 constant decrease, as would be expected, since the increase of cal- 

 cium in thiosulfate must have been at the expense of the calcium 

 in the sulfide. The same holds true for the sulfur in sulfides. 



On the first day the ratio of calcium in thiosulfate to calcium in 

 sulfides was 0.08 to 0.64, or as 1 to 8; on the sixteenth day the ra-' 

 tio of calcium in thiosulfate to calcium in sulfides had increased to 

 34 to 52, or more than 5 to 8. 



Likewise the ratio on the first day of the sulfur in the thiosul- 

 fate to sulfur in the sulfides was 1 to 13, while on the sixteenth day 

 it had increased to nearly 4 to 13. This disagreement between the 

 two ratios would be expected if the explanation regarding the cal- 

 cium and sulfur in table I be accepted. The ratio of calcium in 

 sulfides to sulfur in sulfides on the first day is 64 to 211, while on 

 the sixteenth day the ratio had changed to 52 to 182, or, in terms 

 of the first, to 64 to 224. This difference in ratio in calcium and 



