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COMMERCIAL ROSE CULTURE 



ing its vapors. This was probably the result of a fertile imagi- 

 nation, but withal it must be handled with great caution. The 

 cyanide is permanent in dry air but is decomposed in moist air 

 so that, when water is added, the deadly gas is quickly formed. 

 To make sure of this, and to hasten the decomposition of the 

 cyanide, sulphuric acid is added to the water. A small lump 

 of the cyanide left exposed in a chest where seeds or specimens 

 are kept, will be slowly decomposed by the moisture in the case, 

 and give off enough gas to kill insect life. 



Copper, sulphur, and lime are principally used in the various 

 mixtures used for the spraying of trees. Soot is valuable on the 

 foliage and on the ground as a preventive of fungous diseases, 

 but must not be dusted near flowers, or it will disfigure them. 



ROSE DOROTHY PERKINS 



