Lime-Sulfur 55 



finds its way under the edges of the Httle 

 shell under which the insect lives, shutting 

 off the outside oxygen and rapidly con- 

 suming what remains inside. 



The fungicidal action of lime-sulfm* is 

 thot to be due to the sulfur deposited from it. 

 This, in the air, oxidizes slowly to sulfur 

 dioxid which is toxic. 



Long boihng exposed to the air, as is neces- 

 sary in laboratory manipulation, is harmful 

 to the product as the polysulfids react rapidly 

 with the oxygen of the air depositing sulfur 

 and forming thiosulfate, 



CaSs + 30 = CaSaOa + 3S. 



This is the change that takes place when 

 hme-sulfur stands exposed to the air. At 

 first only a film of sulfur is seen as the cal- 

 cium thiosulfate dissolvs, but as the upper 

 layer becomes saturated with thiosulfate 

 crystals these become mixt with the sulfur 

 forming a hard crust. It is evident from this 

 that the mixture should not stand in the 

 laboratory any longer than necessary. 



The action of lime-sulfur when used as a 

 spray follows from the explanation in the 

 previous paragraf. First, it rapidly takes 

 up oxygen forming calcium thiosulfate and 

 depositing all the sulfur in excess of two atoms 

 to the molecule. Second, the thiosulfate 



