E. HORTON AND E. 8. SALMON 277 



thiosulphate solution and diluting to 100 c. cm. This was applied (Ex- 

 periment 35) and some fungicidal action was observable. The patches 

 on the sprayed leaves were all barren on the second day after spraying; 

 by the fourth day conidiophores had begun to be developed from some 

 of the patches, and by the seventh day clustered conidiophores either 

 covered these patches or had developed round their edges. The solution 

 thus proved ultimately non-fungicidal. 



Calcium hydroxyhydrosulphide. A concentrated solution of calcium 

 hydrosulphide was prepared in the manner described by Divers and 

 Shimidzu {Chem. Soc. Trans. 1884, 45, 272) by bubbling hydrogen 

 sulphide through a suspension of pure calcium hydroxide in water, fresh 

 lime being added at intervals as the liquid becomes clear. A pale yellow- 

 solution was obtained which was diluted for analysis and use. The mono- 

 sulphide sulphur was estimated by Chapin's method. 



Commercial lime-sulphur solution (concentrated) contains about 

 6 per cent, of monosulphide sulphur. Hence a wash diluted to the extent 

 of 1 in 150 (which we found to be the minimum fungicidal strength for 

 hop-mildew) will contain 0-04 per cent, of monosulphide sulphur. Ac- 

 cordingly spray solutions (each containing 10 c.cm. per 100 c.cm. of the 

 10 per cent, calcium caseinate solutions) were prepared by diluting this 

 calcium hydrosulphide solution so as to contain the required amount of 

 monosulphide sulphur. 



Experiment 27. 0-04 per cent, monosulphide sulphur and 1 per cent. 

 calcium caseinate. The solution was non-fungicidal; conidiophores were 

 re-formed 24 hours after the spraying, and the patches were densely 

 "powdery" by the fourth day. 



Experiment 30. 0-34 per cent, monosulphide sulphur and 0-5 per cent, 

 calcium caseinate. The solution was non-fungicidal; the patches bore 

 fresh conidiophores by the second day, and became "powdery" soon 

 afterwards. 



Experiment 29. 0-85 per cent, monosulphide sulfihur and 0-5 per cent, 

 calcium caseinate. On the second day after spraying, the patches were 

 practically obhterated by the deposit from the spray-fluid and were 

 barren. By the fifth day conidiophores had begun to develop from most 

 patches (chiefly from their edges), even where the deposit had completel}^ 

 covered the patch. By the ninth day it was quite evident that the 

 solution was non-fungicidal, most of the patches being as powdery as 

 those on the " control " leaves. 



Calcium pohjsulphide. Calcium hydrosulphide solution was prepared 

 as described above and the monosulphide sulphur estimated. A measured 



