
New York AGRICULTURAL EXPERIMENT STATION. 401 
as a fairly reliable indication regarding the purity of the com- 
pounds mentioned. When adulterants are added, they nave 
generally been found to exist in the form of some finely powuered 
white substances, such as barium sulphate, gypsum, ete., which 
are insoluble in water, acids or alkalies. 
IMPORTANCE OF Ustna PurE CHEMICALS AND MIXTURES. 
Contradictory results have been obtained’ in using copper com- 
pounds and prepared mixtures for spraying fruit trees, grape 
vines, etc. Itis suggested that, in many cases, the widely vary- 
ing results may have been due to the use of impure copper 
compounds, which failed to make spraying mixtures of the 
required degree of strength. The use of commercially prepared 
mixtures of inferior strength may also account for some failares. 
It can readily be seen that purity and strength of chemical prepa- 
rations are absolutely necessary, if trustworthy results are to be 
expected. . 
CONCLUSION. 
Fruit-growers who have to use large quantities of copper com- 
pounds should, for the sake of economy, buy the separate ingre- 
dients of some reliable house, that| can guarantee purity. They 
should test their compounds, to make doubly sure, and should do 
their own mixing. Persons who have occasion to use only small 
amounts of spraying mixtures may find it advantageous and 
economical of time to purchase prepared mixtures ready for use, 
provided they can be sure that the preparation is reliable in 
strength, and not extravagantly high in price. 
XXL ,ANALYSES OF SPRAYED GRAPES. 
In September, 1891, the New York city board of health seized 
and destroyed large quantities of grapes, on the ground that they 
had been sprayed with copper compounds and were poisonous. 
This action caused a serious loss to many grape-growers. Mr. D. 
G. Fairchild, representing the United States Department of Agri- 
culture, visited the Hudson river region, where the grapes were 
grown which had been seized. He took pains to secure the worst 
sprayed branches of grapes obtainable from those vineyards from 
51 : 
