416 



[Vol. 9 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



the lime sulphur was washed from 1 of the exposed glass dishes 

 and the reaction determined. It was found to have changed 

 from an initial reaction of beyond the alkaline Ph ran*e of in- 

 dicators available (Ph 10.0) to Ph 6.4. Likewise, at the end of 

 the same length of time the mixture was washed from one of the 

 vessels in the second set and tested for its reaction. The reaction 

 in this case remained beyond P H 10. 



At the end of 6 hours the reactions were again delermined. 

 The wash from the first set remained the same. In the second 

 set the reaction had changed to Ph 7.4 and in the third siet it was 

 still beyond Ph 10. At the end of 24 hours a third set of readings 



Mannite -ti 5 PQfNaQ t i' 

 Dufkred Mxtur v 



Fig. 3. Germination 

 cultures: toxic actios of 



loidal sulphur 



without sulphur 



of spores of Gloeosporium venetum in hanging-drop 



: of 



flower a of sulphu r ; 



; of hydrophilie colloidal sulphur 



hydrc phobic col- 



; check, 



was made. All gave the same reaction, P H 6.4. The mixture 

 placed under the third condition did not dry out, but changed 

 in reaction to the same point as the others. It would appear 

 from these results that the lasting action of lime sulphur is not 

 due to its causticity. 



At this point it was thought advisable to make some chemical 

 determinations of the exposed or changed lime sulphur. Using 

 the same method as that listed by the Association of Official 

 Agricultural Chemists ('20) it was found that polysulphides were 

 absent. The percentage of thiosulphates as determined by the 



