ZINC SULPHOCARBOLATE. 167 



and summer wheat treated on 6, 16, 20 June and 5 July were 

 free from rust and gave an excellent yield in grain, 284 grammes 

 against 240 grammes on the check plot of the same size. He re- 

 garded this preparation as efficient against rust. Fairchild was less 

 fortunate. The experiments undertaken by him to prevent — 



Phyllosticta spharopsidea, E. and E. (spots of the leaves of the 

 chestnut), Entoviosporium macidatum (spots of the leaves of the 

 pear, leaf scald), gave a negative result. 



6i. Silicate of Zinc. — Phyllosticta splicer ojjsidea and Entomo- 

 sjyorium mamilatiim, Lev. — Silicate of zinc bouillie produces no per- 

 ceptible effect. 



62. Zinc Ferrocyanide. — The zinc ferrocyanide bouillie examined 

 by Fairchild although perfectly adherent had no appreciable effect 

 against Entomosporium niaculatmu, Lev. (spots of the leaf of the pear- 

 tree), whilst injuring the leaf. 



63. Sulphocarbolate of Zinc. — The phenol sulphonic salt of zinc 

 cannot prevent Peronospora riticola (mildew), nor replace copper pre- 

 parations. All attempts to replace copper salts by zinc salts have 

 failed, because the latter have no salutary effect except in large doses 

 with which plants cannot be put in contact ; besides as the sporicidic 

 capacity of zinc salts is not superior to iron salts, they can in no 

 way act similarly to copper salts, and can never replace these in their 

 numerous prophylactic and therapeutic applications. 



64. Cadmium Sulphate, CdS044HoO. — Preparation. — By 

 roasting cadmiferous blends, or by dissolving cadmium oxide or car- 

 bonate in sulphuric acid. 



Properties. — Cadmium sulphate is very soluble in water ; it 

 dissolves in a little less than double its weight of water ; its crystals 

 are colourless. By dissolving sulphate of cadmium by an excess of 

 soda or by milk of lime, a white gelatinous cadmium hydrate is 

 obtained soluble in ammonia. 



Use. — Peronospora riticola, De By. (mildew of the vine). — Cad- 

 mium sulphate was tried comparatively against copper sulphate, like- 

 wise a bouillie made from cadmium sulphate and milk of lime was tried 

 against bouillie bordelaise. Eavaz and Bonnet made in 1898 five 

 sprayings on vines, 14 and 25 May, 22 June and 3 August, and 

 some days before the fall of the leaf, with (1) O'S, 1-0, and 2 per 

 cent bouillie ; (2) a 0*5 and 0-25 per cent solution of sulphate of 

 cadmium on a neighbouring plot ; (3) spraying with bouillie bordelaise 

 of 0-5, 1-0, and 2-0 per cent, and (4) a solution of copper sulphate of 

 0-25 and 0'5 per cent. They found that preparations with a cadmium 

 basis of equal strength had the same anticryptogamic effect as those 

 with a copper basis. Analogous experiments by Sbrozzi, and by 

 Guocdenovic, did not give such favourable results ; they found the 

 action of preparations with a cadmium basis always inferior to corre- 

 sponding preparations with a copper basis, and regard cadmium salts 

 as incapable of replacing copper salts in the struggle against anti- 

 cryptogamic diseases of plants. Passerini also found that cadmium 

 salts are incapable of replacing copper salts, because their anti- 

 cryptogamic action is too weak. 



