The Rhizoctonia Damping-Off of Conifers 



31 



Copper carbonate of technical grade was procured from the J. T. Baker 

 Chemical Co., of Phillipsburg, New Jersey. 



Mercuric chloride, U. S. P. IX, was obtained from Merck & Co., and 

 mercurous chloride (calomel) from the Mallinckrodt Chemical Works, of 

 New York City, under the trade name Calogreen. For the experiments 

 with dry chemicals these two materials were diluted with talc. 



The organic mercury preparations contained as their toxic ingredient 

 either chlorophenol mercury (hydroxymercurichlorophenol sulfate), cyan- 

 cresol mercury, or nitrophenol mercury (hydroxymercurinitrophenol 

 sulfate). Of these preparations, Uspulun, Bayer compound, Bayer 

 dust, and preparations 1-8, II-6, 101, and 112, were furnished by the 

 Bayer Company, of New York City. Their toxic constituents are as 

 follows: 



Name of preparation 



Name and percentage of toxic constituents 



Approximate 



solubility of the 



toxic constituents 



in water 



Bayer compound 



Bayer 1-8 



Bayer II— 6 



Bayer dust 



Dipdust 



Bayer 112 



Bayer 101 



Uspulun 



10% nitrophenol mercury 



8% nitrophenol mercury 



6% nitrophenol mercury 



4% nitrophenol mercury 



2% nitrophenol mercury and 6% chlorophenol 

 mercury 



3% nitrophenol mercury and 3% chlorophenol 



mercury 



10% chlorophenol mercury 



30% chlorophenol mercury 



(Per cent) 

 Complete 



5 

 10 



5 



20 



5 



80 

 Complete 



Semesan Bel, Semesan, and Semesan Jr., obtained from E. I. du Pont 

 de Nemours & Co., of Wilmington, Delaware, contained respectively 10 

 per cent, 35 per cent, and 10 per cent of chlorophenol mercury. This 

 chemical as it occurred in Semesan was almost completely soluble in water, 

 in Semesan Bel it was only slowly soluble, and in Semesan Jr. approximately 

 one-third was immediately soluble. 6 



Germisan, containing approximately 31 per cent of cyancresol mercury, 

 was obtained from the Saccharin-Fabrik, Aktiengesellschaft, Magdeburg 

 Siidost, Germany. 



The mercury content of chlorophenol mercury is 61 to 02 per cent, in 

 comparison with 55 per cent in nitrophenol mercury, 73.89 per cent in 

 mercuric chloride, and 84.96 per cent in mercurous chloride. 



'■ Several changes have been made in the composition of two of these preparations since the experiments 

 here reported were conducted. Thus, as manufactured in June, L928, Semesan Bel contained the chloro- 

 phenol mercury in a form which was about 40 per cent immediately soluble, while Semesan Jr. contained 

 as the toxic constituent 12 per cent of cresol mercury, approximately 40 per cent of which was readily 

 soluble. 



