178 Report OF THE BOTANICAL DEPARTMENT OF THE 
Upon standing a slight deposit of gypsum is formed leaving a deep blue 
solution of hydrate- of copper. If desired the spray may be applied im- 
mediately after preparation as the small amount of finely divided gypsum 
will not interfere. Prepared in this manner the solution contains about the 
same amount of copper hydrate as the ordinary bordeaux mixture. It may 
be diluted indefinitely with water without a precipitate forming. The solu- 
tion should be kept in well stoppered bottles and is best if used within 48 
hours after preparation. 
In case complete solution of the copper hydrate is not obtained, add a 
little more of solution No. 2 of sucrate of lime. 
It is believed, on account of the soluble condition of the copper hydrate 
in this preparation, that its efficiency as a fungicide will be much greater 
than in the ordinary bordeaux mixture and consequently that it may be 
diluted at least ten and possibly fifty times and still protect plants from 
the ordinary fungus diseases. In addition to this advantage the absence 
of solid particles permits the use of a much finer spray than is now em- 
ployed and it is evident that with a fine spray much more surface can be 
covered with the same amount of material. In these two ways it is hoped 
that the expense for the materials used in spraying may be greatly reduced. 
Soda bordeaur.—Considerable interest in soda bordeaux for 
potatoes has been aroused recently by Prof. 8S. Fraser** who calls 
attention to the fact that some experiments made in Ireland tend 
to show that soda bordeaux is superior to the regular lime bor- 
deaux as a preventive of potato blight.*® The experiments men- 
tioned extended over three years, included nine varieties, and each 
year soda bordeaux eave better results than lime bordeaux. ‘The 
average yield per acre for the three years was as follows: Lime 
bordeaux, 370 bushels; soda bordeaux, 391.7 bushels; unsprayed, 
303.9 bushels. Thus the lime bordeaux gave an average gain of 
66 bushels and the soda bordeaux, 88 bushels per acre. ,The lime 
bordeaux was made by the &8-4-40 formula or the 1-to-5 formula, 
which is stronger than it is used in this country. The soda bor- 
deaux, also, was made by the 1-to-5 formula with 10 pounds of 
washing soda (sal soda) substituted for the lime. 
As these results are not in harmony with accepted heer on 
the subject the writers thought it advisable to make farther ex- 
periments comparing soda bordeaux with lime bordeaux and 
with Dr. Babcock’s soluble bordeaux. 
Fraser, S. Treatment for Potato Blight. Country Gentleman, 69:510. 
June 2, 1904. 
Ibid. A New Treatment for Potato Blight. American Agriculturist, 73: 
668. June 18, 1904. 
Ibid. The Potato, p. 131. Orange Judd Co., New York. 1905. 
#°Prevention of Potato Blight. Department of Agriculture and Technical 
Instruction for Ireland. Leaflet No. 14, 
