360 Report oF THE CHEMIST OF THE 
the disturbing effects noticed are the result of inhalation of 
hydrogen sulphide gas given off during the preparation of the 
lime-sulphur mixture and that the formation of the gas is due 
to the use of lime containing magnesium oxide. 
It may be stated also that when magnesium oxide is added 
to a concentrated mixture of calcium pentasulphide (Ca’S,), 
which is usually the chief constituent of the lime-sulphur prep- 
aration, hydrogen sulphide gas is formed, resulting in loss of 
calcium pentasulphide. 
METHODS OF ANALYSIS. 
For the benefit of those interested in the analytical methods 
employed in obtaining our results, we give a brief outline. Con- 
Stituents other than sulphur were determined by the methods 
in common use. (1) Zotal sulphur in solution is determined by 
oxidizing to sulphate with alkaline solution of hydrogen per- 
oxide, following in essential details the Avery method (U. 8. 
Dept. Agr., Bureau of Chemistry, Bul. 107, p. 34). The use of 
bromine as an oxidizing agent was carefully tried but the re- 
sults were less satisfactory. (2) Thiosulphate sulphur in solu- 
tion is determined by the ammoniacal zine chloride method. 
(U. 8S. Dept. Agr., Bureau of Chemistry, Bul. 101, p. 9.) (3) 
Sulphide sulphur in solution is found by subtracting the 
amount of thiosulphate sulphur from total soluble sulphur. 
(4) Free sulphur, as in sediment, is determined by extraction 
with carbon bisulphide in the usual manner. (5) Sulphite 
sulphur is estimated by treatment with excess of standardized 
iodine solution, titrating excess with standardized solution of 
sodium thiosulphate. 
EXPERIMENTAL WORK. 
In the work carried on here, a study has been made of 
various points connected with the preparation of the lime- 
sulphur mixture with special reference to the difficulties ex- 
perienced by fruit-growers in making their own concentrated 
solutions. Among the questions thus raised, we mention the 
following: (1) Why do home-made preparations often vary so 
much in concentration when prepared at different times? 
