EXPERIMENT STATION BULLETINS. 373 



FOREWORD. 



Technical Bulletin No. 6. 



The importance of the lime-sulfur solution, both as an insecticide 

 and fungicide is increasing each year. In many sections it is now the 

 only remedy used against the scale insects and it is fast replacing Bor- 

 deaux mixture as a summer spray. 



Many exceedingly interesting observations were made during the prog- 

 ress of the work here reported, for which, as yet, no satisfactory ex- 

 planations have been reached. These will be taken up for further in- 

 vestigation as opportunity permits. 



The methods of analysis used have made it possible to gain more in- 

 formation upon the composition of the polysulfides. In table V, page 10, 

 it will be observed that the ratio between the mono-sulfide and poly- 

 sulfide sulfur, in all but three cases, is almost exactly one to four, 

 proving, in these cases at least, that the sulfide sulfur is in the form of 

 calcium pentasulfide (CaSj). In these cases the sulfur was in excess. 

 In the three exceptions (2A, 2B and 6 A) the limes used were compara- 

 tively pure and the calcium was in excess, making the formation of 

 calcium pentasulfide impossible. 



From these observations together with other unpublished results we 

 are led to the conclusion that when the ratio between the calcium 

 and sulfur is greater than 1 to 21^ the sulfide sulfur is present as 

 calcium pentasulfide. When a greater amount of lime is used the sul- 

 fide sulfur is present as a mixture of the lower sulfides together with 



some pentasulfide. 



A. J. Patten. 



