350 
NO. 22.— ZINC BORATE MIXTURE. 
(Rows 22 and 22*.) 
33.36 grams zinc sulphate (ZnS0 4 , 7H 2 0). 
33.36 grams sodium borate (borax) (Na 2 B 4 0 7 , 10H 2 O). 
1 gallon of Avater. 
Chemical votes. —A remarkably gelatinous precipitate of a milky white color. The 
above proportions are necessary, as a variation either way from equal parts gives a 
precipitate which settles very rapidly. It is a compound of very vague composi¬ 
tion (see Watts’ Dictionary. 1888, p. 530). The reaction would be written ZnS0 4 , 
7H 2 0+Na 2 B 4 0 7 , 10H 2 O = ZnB 4 O 7 -|-Na 2 S0 4 + 17H 2 0. A zinc borate and a sodium 
sulphate are in combination in the spraying mixture. 
Bernards. —This mixture is much more difficult of preparation than ammoniacal 
solution, covers the foliage less completely, and adheres with about the same tenac¬ 
ity. It proved markedly inferior in retarding the progress of the disease and injured 
the foliage slightly. The treated rows were 1 and | grades better than adjacent 
untreated rows on September 2, and 0 and 0 better on October 13. A mixture with 
no qualities to recommend it for further trial. 
NO. 23.— ZINC FERROCYANIDE MIXTURE. 
(Rows 23 and 23'.) 
33.36 grains zinc sulphate (ZnS0 4 , 7H 2 0). 
66.72 grams potassium ferrocyanide (yellow prussiate of potash). 
1 gallon of water. 
Chemical notes. —A yellowish white precipitate is formed by the reaction, settling 
very slowly. An increase of zinc sulphate causes a heavy precipitate to be formed, 
which sinks very rapidly. According to Watts’ Dictionary, 1889, p. 337, the formula 
is Zn 2 FeCy 6 , 3H. 2 0. The solution sprayed upon the plants contains in combination 
zinc ferrocyanide and potassium sulphate. 
Bernards. —This mixture is much more difficult of preparation, covers the foliage 
no more effectively, and adheres with about the same tenacity as the ammoniacal solu¬ 
tion. It proved wholly ineffective in retarding the progress of the disease and 
injured the foliage, necessitating a dilution to 2 gallons. The treated rows were 0 
and 0 grades better than untreated adjacent rows on September 2, and 0 and 0 on 
October 13. 
No. 24.— ZINC SILICATE MIXTURE. 
(Rows 24 and 24 1 .) 
33.36 grams zinc sulphate (ZnS0 4 ,7H 2 0). 
58.38 grams sodium silicate (water glass). 
1 gallon of water. 
Chemical notes .—An opalescent fluid with a precipitate which sinks very slowly. 
It is a compound of which little seems to be known. Watts does not include it. 
The chemical reaction would be written ZuS0 4 , 7H 2 0 -j-Na 2 Si0 4 = ZnSi0 4 -l-Na 2 S0 4 -{- 
7H. 2 0. The mixture therefore contains zinc silicate and sodium sulphate in combi¬ 
nation. 
Bernards. — This mixture is more difficult of preparation, does not cover the foliage 
any better, and is less adherent than ammoniacal solution. It proved wholly with¬ 
out effect in retarding the progress of the disease and injured the foliage slightly. 
The treated rows were 0 and 0 grades better than adjacent untreated rows on Sep¬ 
tember 2, and 0 and 0 on October 13. 
No. 25.— ZINC SULPHIDE MIXTURE. 
(Rows 25 and 25'.) 
33.36 grams zinc sulphate (ZnS0,,7H 2 0). 
66.60 grams potassium sulphide (liver of sulphur). 
1 gallon of water. 
