Aug. i8,1923 
Sulphur Compounds in Dry Lime-Sulphur 
329 
The method as represented by the first equation might be designated 
as the carbonic acid method, and is called method A; the other, as rep¬ 
resented by the second equation, might be designated as the hydro¬ 
chloric-acid method, and is referred to as method B. 
No attempt is made by the use of either of the proposed methods to 
calculate the amount of polysulphid sulphur present in the dry lime- 
sulphur mixture, because of the uncertainty as to just what proportion 
of the residual sulphur (contained in the reaction flask) can be attributed 
to polysulphid sulphur and what amount to soluble free sulphur. 
The same uncertainty is apparent upon application of methods based 
on aqueous solutions of polysulphids. If the lime-sulphur mixture con¬ 
tained free sulphur, the addition of water resulting in the solution of the 
lime-sulphur compounds would naturally precipitate some if not all of 
the free sulphur in solution, the quantity deposited depending upon the 
dilution. On the other hand, the hydrolysis of polysulphids in aqueous 
solutions results also in the xieposition of sulphur, the amount depending 
upon the dilution and temperature of the solution and the concentration 
of calcium hydroxid formed. In either case, whether methods are applied 
to the dry lime-sulphur products or to solutions of the same, it is quite 
impossible to differentiate accurately between true polysulphid of sulphur 
and free sulphur in solution. 
The true polysulphid sulphur might be estimated with some accuracy, 
provided there existed a method for determining different amounts of 
free sulphur in the presence of water soluble polysulphids. 
The fact is recognized by the writer that title total amount of soluble 
sulphur can be estimated only by analysis of the solutions of lime- 
sulphur mixtures. But in such analyses the solution used should be of 
the same concentration as that used for spray or as that recommended 
by the manufacturer of the product. 
EXPERIMENTAL TESTS WITH METHODS A AND B 
The samples of dry lime-sulphur used in the following experiments were 
received from the same manufacturers upon two different occasions. 
The results given in Table I are from a sample received and analyzed in 
1919. All other results are from a sample received and analyzed in 1921. 
The methods taken for comparison were the HC 1 and iodin methods 
recommended by Averitt. They were chosen because of the advantages 
claimed by the originators and others. There can be no criticism in 
regard to the quickness and ease of manipulation, but the inaccuracy of 
results is clearly apparent from the following work. 
It was thought that numerous comparisons were unnecessary, pro¬ 
vided it could be proved that the use of H 2 C 0 3 results in a quantitative 
separation of the monosulphid sulphur from the thiosulphate sulphur 
and that the use of an excess of C0 2 has no appreciable effect upon the 
calcium thiosulphate in solution. The experimental work as given in the 
following pages is believed to substantiate the accuracy of the proposed 
methods. 
54485—23 - i 
