1922] 



YOUNG — THE TOXIC PROPERTY OF SULPHUR 405 



driticum, F. Pyrinum, Botrytis cinerea, and Nectria ditissima. 

 They conclude that sulphur dioxide cannot be a factor. 



Marcille ('11) attributed the toxic property of sulphur to 

 sulphur trioxide and sulphuric acid in the control of grape mil- 

 dew. A similar conclusion was arrived at by Moissan ('04) who 

 was able to obtain this gas from the spontaneous oxidation of 

 different kinds of sulphur at ordinary temperatures. As far as 

 the author is aware, these results have never been confirmed, and 

 Bourcart (13) and Barker, Gimingham, and Wiltshire ('20) 

 proved on the contrary that sulphur trioxide and sulphuric acid 

 do not contribute to the fungicidal property of sulphur. 



That sulphur is toxic because of its volatilization as such is 

 probably the view most commonly held at the present time. 

 The fact that spores are inhibited in germination when not in 

 direct contact with the sulphur particle has been frequently dem- 

 onstrated. Smith ('06), working with asparagus rust, con- 

 cluded that sulphur acts by its fumes but that the sulphur must 

 be uniformly distributed to be effective in controlling the disease. 

 He found that the disease was best controlled in air pockets which 

 aided in preventing a too rapid spreading and dilution of the 

 fumes. Similar views are held by Mares and Mohr (see Bour- 

 cart, 13), Bioletti ('07), Bourcart ('13), Barker, Gimingham, 

 and Wiltshire ('20), Doran ('22), and others. 



The conditions under which sulphur is volatile or under which 

 volatile substances are formed from sulphur have been inves- 

 tigated by Marcille (11), Bourcart (13), Blodgett (13), Kuhl 

 /21), and Doran (17, '22), with the following general con- 

 clusions : ( 1 ) a certain temperature must be maintained, usually 

 above 25° C; (2) oxygen is necessary; (3) sunlight is a possible 

 factor; (4) the influence of the leaves and spores is considered 

 by some a factor. These conclusions were arrived at by the use 

 of flowers of sulphur. 



The toxicity of other forms, such as finely divided sulphur and 

 the various sulphides, has been investigated by a number of 

 workers. Doran ('22) found that Schloesing's precipitated sul- 

 phur 1 was more effective in killing spores of Venturia inaequalis 

 than any of the finely divided sulphurs used. Atomic sulphur 2 

 has been reported effective. 



1 Manufactured by Usines Schloesing Freres et Cie., of Marseille, France. 

 'Prepared by the General Chemical Co., New York and Baltimore. 



