J. V. Eyrk, E. S. Salmon and L. K. Wormald 305 



polysuljjhides for comparison with one containing some of the higher 

 ones. The analyses of the solutions j^repared show that solutions 

 Nos. VIII and IX were different from Solution XI with which they have 

 been compared. In the preparation of these two solutions, that is VIII 

 and IX, the attempt seems to have been successful in producing a 

 solution of the lower polysulphides of ammonia; the analysis showing 

 them to contain practically nothing else than the ammonium tri-sulphide 

 (NH4)2S3. On the other hand, Solution XI appears from the analysis 

 to contain some high polysulphides. It is interesting, therefore, to find 

 that solutions VIII and XI agree so completely when compared on a 

 polysulphide basis, and this seems to indicate that equal amounts of 

 polysulphide sulphur, whether the polysulphides present be high or low 

 . polysulphides, behave in precisely the same way fungicidally. In a 

 previous attempt to discover whether the polysulphides are active as such 

 in killing the fungus, or whether this property is due to the sulphur 

 deposited when these compounds decompose, evidence was found 

 favouring the former view. This was based upon some attempts to 

 weigh directly the amount of sulphur deposited from solutions of colour- 

 less ammonium hydrosulphide and yellow ammonium sulphide. As 

 was suggested then it was necessary to repeat and extend these experi- 

 ments. Work along these lines has given very conflicting results and 

 we are not inclined now to place as much reliance as formerly upon 

 the evidence then at hand; unfortunately we have not been able to 

 obtain concordant results. In this connection, however, the behaviour 

 of some of the stock solutions, for example No. X, proves of interest. 

 This solution was not stable when diluted with water and much sulphur 

 was deposited. The fungicidal action of this solution, rendered opaque 

 by the addition of water, was compared with that of Solution XI when 

 both were diluted to contain 0-078 % polysulphide sulphur and I % 

 soft soap. The fluid made from Solution XI was quite clear at the time 

 of spraying while that from Solution X was yellow and opaque owing 

 to the deposition of sulphur. Both liquids were found to have the same 

 effect on the fungus. This comparison was repeated this time after 

 the diluted Solution X had stood for two hours to secure as completely 

 as possible the precipitation of sulphur. After agitation liquid No. X 

 was contrasted with liquid No. XI and again the two solutions behaved 

 similarly. This result seems to show that a high polysulphide solution 

 may deposit some of its sulphur without losing any of its fungicidal 

 power and suggests that the freshly precipitated sulphur may have 

 some action on the fungus. In view of this result and a possible action 



