480 Fii)i(/ici(/al rropertii's of Certain Spnnj-Flnids 



Sodium iJiiosulphiilc. The onliiiarv coiiiiiiercial crvstalliiie material 

 was used. 



Ammonia. The aiiiinonia solutions used were prepared from a 

 strong solution which contained 21-7 % ammonia (sp. gr. O-IH 1 at I5°C.) 

 by diluting it with water. 



Caustic soda. The substance used was that usually sold in stick 

 form. 



Hydroijen sulphide. Distilled water, after having been boiled to 

 expel air, was cooled and saturated with the purified gas. The amount 

 of sulphide-sulphur present was found to be 0-113 %. 



Iron sulphide. Two methods were followed in the pre])aration of 

 this material; (i) a weighed i|uantity of crystallised ferrous sulj)liate 

 was dissolved in water and a dilute solution of yellow ammonium 

 sulphide added drop by dro]) until the fornuition of iron sulphide 

 seemed complete; (ii) a dilute solution of ferrous sulphate was added 

 to a known quantity of ammonium hydrosulphide solution until no 

 further precipitation occurred. It should be mentioned that when 

 made according to method (i) the iron sulphide remains longer in a 

 fine state of division and is consequently in a better form for applying 

 as a fine spray. 



I. Various Substances. 



Soft .soap. 

 Hops, iitll. 

 Exper. 1. Solution containing 1 % soft .soap. 



2nd day. The majority of the patches showhig a vigorous growth of coiiidiophores. 

 lird day. All the patches of mildew now as vigorous and as "powdery"' a.s before 

 .spraying. There was no injury to (he Icaf-cclls at any place. 



191.5. 

 Exper. 1. Solution containing 1 % soft soap. 



2nd day. The patches of mildew scarcely checked; all showing an almndant 

 growth of young conidiophorcs. 



'^rd day. All the patches now "[lowdery." 



Saponin. 



Hops. 11)11. 



Exper. 1. Solution containing 0-2.5 % saponin. 



Is/ day. INfildow little affected. 



3rd day. All tlic patches of mildew vigorou'^ and "powdery." 



