THE MONTHLY BULLETIN. 273 



The Effect of Acids on the Fungicides. 



Bordeaux. The common acids (with the exception of carbonic 

 acid) dissolve the precipitated copper of Bordeaux mixture. 



Lime-sulfur. All acids, including carbonic acid, precipitate free 

 sulfur from lime-sulfur solutions. 



Iron-sulfid. The stronger acids dissolve the iron sulfid of the 

 paste, liberating hydrogen sulfltl. 



The Effect of Alkalies on the Fungicides. 



Bordeaux. Excess of the strong alkalies dissolves the precipitated 

 copper of Bordeaux mixture and form new compounds which are suit- 

 able for use in many instances, if the necessary caution is used. 



Lime-sulfur. Lime-sulfur is broken up by the strong alkalies. 



Iron-sulfid. The strong alkalies will dissolve the precipitated 

 sulfur of the paste and form caustic compounds. 



The Effect of Alkalies and Acids on the Arsenicals. 



All of the arsenites are more or less decomposed by either acids or 

 alkalies, producing soluble forms of arsenic. The acid lead arsenate is 

 unstable in the presence of alkalies, while the neutral form is unstable 

 in the presence of acids. 



The Effect of Alkalies and Acids on the Contact Insecticides. 



Emulsions. Enuilsions are broken up by either alkalies or acids, 

 and the liberated oil may cause injury on account of uneven distribution. 



Soaps. More alkali added to a soap will not affect its properties. 

 If injurious effects are produced, it will be from the alkali and not from 

 the change in composition of the soap. Soaps are decomposed by the 

 strong acids. The fatty acids are freed from the base and are no longer 

 a part of the soap. 



Tobacco. It is believed that alkalies would have no effect on free 

 nicotin in extracts. Nicotin sulfate, however, would be decomposed by- 

 alkalies. The sulfate part of the compound would unite Avith the alkali 

 and the nicotin would be set free. In this form the alkaloid would be 

 just as active, and probably more so, but would be more liable to loss by 

 volatilization. Acids would have no effect upon the different tobacco 

 preparations. 



Spraying, Followed by Cyanid Fumigation. 



Paris green, as well as the copper of Bordeaux mixture, is readily 

 soluble in solutions of cyanid. Copper compounds in general form com- 

 plex soluble salts with cyanids and soluble copper is injurious to foliage. 

 Trees sprayed with any form of copper should not subsequently be fumi- 

 gated with cyanid without the lapse of at least one year, on account of 

 the solvent action of the cyanid on the copper. 



So far as known, there is no danger of this character from the use of 

 the other sprays. 



