802 Fungicidal Properties of Certain Spraji-fltiidH 



If we Ponipare first tliP seven leaves sprayed with amiiinniuin 

 ehlorido witli the seven leaves sprayed with the soap solution, we find 

 tiia( tlie condition of the mildew on the eleventh dav was as follows: 



Patches unaffected ... 



Checked, but .some patches with clustered 



eonidiophore.s 

 Leaf discarded (mildew apparently dying 



away naturally) ... ... ... ... 7 7 



* Tip of leaf sliowing '"scorching" injury. 



The seven leaves sprayed with ammonium chloride compared with 

 the opposite leaves at the same' node sprayed with Solution XI after 

 precipitation of sulphur (and containing 0-28 % ammonium chloride) 

 were class jfied on the eleventh day as follow's: 



Sol. XI after precipita- Amnioniuni 



tion of sulphur chloride 



No. of leaf No. of leaf 



Fungicidal 8*, 10*, 11*, 12 — 



Discarded a.s too jioor material !)*, 13, 14 !)*, 13. 14 



.\ I most fungicidal (a very few scattered coni- 



liiophorcs from a few patches) ... ... — 8*. 10*, \'l 



A few pati'hcs sterile; most patches with 



fresh clustered conidiophores ... ... — II* 



* Tip of leaf showing "scorching" injury 



There is, therefore, some evidence that the precipitated sulphur 

 e.xerted a fungicidal action, although owing to the poor material used, 

 this evidence cannot be considered as conclusive. 



Theoretical Considerations. 



Ill <uir previous communication we brought forward evidence showing 

 that the fungicidal value of alkaline sulphide solutions is not to be 

 ascribed to the total amount of sulphur such solutions contain, nor to 

 the proportion of sulphur which is present in the form known as sulphide 

 sulphur. We were led to conclude that the soluble polysulphides present 

 were mainly responsible for their fungicidal behaviour. 



During the seasons 1916-17 further evidence was gained in support 

 of this view. On reference to the analyses of the solutions used in the 

 course of this work which are given on page 306 it will be seen that 

 Solution III contained approximately ten times the amount of sulphide 

 sulphur present in Solution II, and eleven times that contained in 

 Solution I. Also Solution III has three times the amount of total sulphur 



