345 
Chemical notes. —The original intention was to have the formula as follows: 14.90 
grams cupric sulphate, 7.45 grams potassic hydrate, and 1 gallon of water, hut by 
a mistake the KHO was double the amount of cupric sulphate instead of being only 
one-half the amount. The original would have formed a basic sulphate, since KHO 
when added short of saturation to CuS0 4 , 5H 2 0 gives a basic sulphate (see Prescott 
and Johnson, l. c., pp. 86-87). The chemical formula of the hydroxide would be 
Cu(OH) 2 , and in addition to the hydroxide present in the mixture there would be 
potassium sulphate. The reaction is the same as for No. 6. 
Remarks .—This mixture is scarcely more difficult to prepare, covers the foliage as 
well, and adheres about as well as ammoniacal solution. It proved markedly supe¬ 
rior in retarding the progress of the disease, but injured the foliage slightly. The 
treated rows were 0 and 2 grades better than adjacent untreated rows on September 
2, and 2 and 2 better on October 13. It is certainly worthy of further trial, and 
is markedly superior to the black hydrate No. 6. 
No. 8.—CUPRIC HYDROXIDE MIXTURE. 
(Rows 8 and 8'.) 
14.90 grams cupric sulphate (CuS0 4 , 5H 2 0). 
26.82 grams potassium hydrate (KHO). 
1 gallon of water. 
Prepared exactly as No. 7. 
Chemical notes .—This mixture, which was intended for the simple hydroxide, was, 
because of a mistake in using an increased amount of potassium hydrate instead 
of a diminished amount (26.83 grams instead of 8.27 grams), applied as a hydroxide, 
with a large excess of KHO. It differed from No. 6 only in not being allowed to 
stand and thus become a black hydrate and from No. 7 in having less KHO. The 
substances in the sprayed mixture were the same as in Nos. 6 and 7, and the reaction 
would be the same. 
Remarks .—In ease of preparation and application and in adhesiveness this mixture 
is like No. 7. It proved superior to ammoniacal solution in retarding the disease, 
but injured the foliage slightly. The treated rows were 1| and \ grades better than 
the adjacent untreated rows on September 2, and 0 and 1^ on October 13. It is 
slightly inferior to No. 7, but superior to No. 6. It differs in composition in no essen¬ 
tial way from No. 7, and the difference in result is probably not significant. 
NO. 9.— TRICUPRIC ORTHOPHOSPHATE. 
(Rows 9 and 9'.) 
14.90 grams cupric sulphate (CuS0 4 , 5H 2 0). 
26.07 grams sodium phosphate (Na 2 HP0 4 , 12H 2 0). 
1 gallon of water. 
Chemical notes .—The pearly blue precipitate thus formed is in all probability the 
tricupric salt mentioned in Watts’ Dictionary, 1866, p. 560, and having the formula Cu 3 
P 2 0 8 . No excess of CuS0 4 was observable in the supernatant fluid. The mixture 
as sprayed upon the plants was composed of copper orthophosphate and sodium sul¬ 
phate. The reaction can be expressed as follows: CuS0 4 , 5H 2 0-t-Na 2 HP0 4 ,12H 2 0= 
CuIIP0 4 -fNa 2 S0 4 +17H 2 0. 
Remarks .—This mixture is more difficult to prepare, but covers the foliage better 
and adheres better than the ammoniacal solution. It proved to have more efficiency 
in retarding the progress of the disease and did not injure the foliage. The treated 
rows were 1| and \ grades better than adjacent untreated rows on September 2, and 
2£ and 0 on October 13. It is a mixture worthy of further trial. 
No. 10.— CUPRIC POLYSULPHIDE MIXTURE. 
(Rows 10 and 10'.) 
j. 4.90 grams cupric sulphate (CuS0 4 , 5H 2 0). 
14.90 grams potassium sulphide (K 2 S 3 and K 2 S 5 with intermediate forms) 
(liver of sulphur). 
1 gallon of water. 
