J. y. Eyre and PI S. Salmon 475 



a 1 % solution of "liver-of-sulishur" against Sphucrothecn pannosa, 

 although it is not stated whether this solution is intended for use on 

 foliage or not. Hollrung^ states that Mohr employed against 8. pannosa 

 on the Rose and Peach a 1-3 % solution of "liver-of-sulphur" containing 

 1-3 % glycerine, wathout stating whether the mixture was used in 

 summer or winter. Against *S'. inors-ucue, the American Gooseberry- 

 mildew, Goff^ recommends the use of a 0-18% to 0-37% solution, 

 and Close*, Beach*, and Duggar^ a solution containing 0-37 %. Against 

 the Vine-mildew (Uncinula necator) Galloway^ recommends the 0-37 % 

 solution ; against the Cucumber-mildew {Erijsiphe Cichoracearuni) 

 Humphrey' recommends as successful a 0-18 % solution. 



It has to be remembered that the substance "liver-of-sulphur" 

 is not a chemical individual substance but rather a mixture of a great 

 variety of sulphur compounds, chiefly sulphides and polysulphides of 

 potassium (or sodium) and that its composition varies according to 

 the mode of its preparation. Also, that its composition changes on 

 the material being kept unless precautions are taken to avoid contact 

 with the air. It is clear, therefore*, that the composition of one sample 

 of "hver-of-sulphur" may differ very widely from another sample 

 which appears to the eye to be ecjually good, a fact which may perhaps 

 explain to some extent the diversity found in the concentrations 

 recommended for use. 



The opinion which has been geiierally held regarding the mode of 

 action of "liver-of-sulphur" appears to be that this substance is valuable 

 by reason of the fact that on exposure to air its solutions readily deposit 

 sulphur in an extremely fine state of division. It is believed in fact 

 that the soluble constituents of the "liver-of-sulphur" — which are 

 chiefly sulphides and polysulphides — do not act per se, although their 

 presence is necessary as giving the required deposit of sulphur. Other 

 views have been put forward attributing the fungicidal action to some 

 oxidation product of the higher sulphides, e.g. the thiosulphate — either 

 present in the spray fluid or produced after spra3dng on the plant. 



1 HoUning, M., Handhuch d. chemischen Mittel gegeii Pflanzenkrankh. ji. 44 (1S08). 

 - Goff, E. S., in Journ. of Mycology, v. p. 33 (1889). 



3 Close, C. P., in New York Agric. Exper. Slat., Bull. 161, p. 1.53 (1899), 

 ^ Beach, S. A., in New York Agric. Exper. Station Bull. p. 114 (1897). 

 ' Duggar, B. M., Fungous Diseasea of Plants, p. 223 (1909). 

 ' Galloway, B. T., in Journ. of Mycology, vi. p. 13 (1891). 



' Humphrey, .J. E., in Rep. Mass. Slate Agric. Exper. Stat. IX- 222 (1892). .and X. 225 

 (1893). 



8 Vide Journ. of Board Agric. xxi. p. 236 (1914). 



