Aug. 18, 1923 
Sulphur Compounds in Dry Lime-Sulphur 
333 * 
HYDROCHLORIC ACID AS A MEASURE OF THE BASICITY OF THE 
SULPHID SOLUTION 
That the number of cubic centimeters of HC 1 used in the direct 
acid titration method can not be taken as an index of the quantity of 
monosulphid sulphur present in lime-sulphur mixtures, but may be 
taken as a measure of the basicity of the solution, is borne out by the 
following experiments. 
Five-tenths gm. charge of dry lime-sulphur was analyzed by the 
carbonic acid method; C 0 2 was passed through the solution for four hours, 
the solution brought to boiling, and the C 0 2 passed through the solution 
for another hour. The contents of the reaction flask, A, containing free 
S, CaC0 3 , Ca(HC 0 3 ) 2 , and CaS 2 0 3 , were then titrated with N/2 HC 1 , 
using methyl orange as indicator. It was found that 8.23 cc. of acid 
we e required to neutralize the solution. 
Upon application of the direct acid titration method (Averitt) it was 
found that 8.26 cc. of N/2 HC 1 were necessary to carry the reaction to 
the end point of methyl orange. The number of cubic centimeters of 
acid used according to the method is the equivalent of the monosulphid 
sulphur present. Therefore the amount of the latter, based on a 0.5 gm. 
sample, should equal 13.24 per cent. 
A comparison of these two simple tests shows that in one case 8.26 cc. 
of N/2 HC 1 were used in neutralizing the polysulphid solution, while in 
the other case almost an equal amount of HC 1 was required to neutralize 
the basic salts present, after the removal of the monosulphid sulphur. 
The only possible deduction is that the HC 1 reacts with not only the 
calcium sulphid but other calcium compounds as well, and consequently 
the amount of HC 1 required can not be used as a direct estimation of 
the monosulphid sulphur present. 
That 13.24 per cent for monosulphid sulphur is much too high is again 
made apparent by completing the former experiment in the usual way. 
The results obtained for the three forms of sulphur are as follows: 
Residual sulphur. 50. 64 per cent. 
Thiosulphate sulphur. 2. 61 per cent. 
Monosulphid sulphur. 8. 35 per cent. 
ABSORPTION SOLUTIONS 
Different absorptive solutions for the evolved H 2 S were substituted in 
place of the hydrated sodium peroxid. Among the solutions tried were 
the following: Ammoniacal H 2 0 2 , ammoniacal ZnCl 2 , ammoniacal CdCl 2 , 
acetic acid solution of Zn^HgO^, dilute standard solution of iodin 
(with a protective flask containing a standard solution of Na^SjOg), 3 to 4 
N KOH and NaOH solutions. 
With the exception of the alkali solutions, all these proved unsatis¬ 
factory for one reason or another. Solutions of hydrogen peroxid in¬ 
variably contain sulphates in greater or less quantity and consequently 
necessitate the employment of exact measured amounts and require 
that blank tests be made upon each lot of peroxid solution used. The 
use of zinc and cadmium solutions, neutral or alkaline, gives precipitates 
of metallic sulphids which are of a decidedly colloid nature. The diffi¬ 
culties attending filtration and washing are well known. Oxidation of 
the sulphids during the operation is a constant source of error tending 
toward low results. The sulphid can not be weighed directly with accu¬ 
racy because of occlusion, and, therefore, must necessarily be changed into 
some other form in order that the estimation of the sulphur content majr 
be made. 
