328 Journal of Agricultural Research voi. xxv, No. 7 
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ADVANTAGES OF PROPOSED METHODS 
The advantages derived from the use of either of the two methods are 
based on accuracy, simplicity of reactions, and the employment of but 
few and simple operations. 
The claim for accuracy is based on the following reasons: 
1. Both methods are based directly on the use of dry lime-sulphur and 
not upon prepared solutions. The methods are applicable, however, to 
solutions of lime-sulphur. 
2. All results are obtained on the one sample throughout the determi¬ 
nation. 
3. The liberation of sulphur, equivalent to the monosulphid sulphur of 
the metal, is made complete by the action of dilute acids upon the poly- 
sulphid in solution. 
4. The evolution of the hydrogen sulphid and the complete removal by 
aid of a gas allows clear and complete separation of the three forms of 
sulphur. 
5. The determination of monosulphid sulphur, when present in large 
quantities, can not be more accurately made than by the evolution 
method; and the absorption, oxidation, and weighing as BaS 0 4 is as 
accurate a method for the final determination as any method yet devised. 
6. The thiosulphate sulphur is determined by the usual and exact 
method of oxidation by means of iodin. 
7. The sulphur remaining after the complete removal of the mono¬ 
sulphid sulphur is readily separated from the thiosulphate solution by 
simple filtration and is determined by weight. 
The application of these methods is simple because: 
1. Complexity in reactions and processes is eliminated by the use 
of one process for the complete separation of the three forms of sulphur. 
2. The time required for the determination is reasonably short, and the 
process of expelling the hydrogen sulphid from solution does not require 
the constant attention of the operator. 
3. The use of a solution, in connection with hydrogen sulphid, which 
answers the purpose of an absorbing and oxidizing agent saves time and 
promotes accuracy. 
DISCUSSION OF METHODS 
These methods do not include any procedures dealing with the detection 
or estimation of any of the possible and theoretical sulphur compounds, 
stated by a few investigators as existing in solution as traces, but are con¬ 
cerned wholly with the determination of the principal constituents con¬ 
tained in the commercial lime-sulphur products, which are considered to 
give to lime-sulphur solutions their insecticidal and fungicidal value— 
namely, monosulphide and residual and thiosulphate sulphur. 
Both methods are based upon the fact that the acids used are ionized 
to a greater extent than the hydrosulphuric, and therefore have the power 
of decomposing completely the polysulphids of calcium, with liberation 
of hydrogen sulphid and deposition of sulphur, according to the following 
equations: 
’ 1. CaS.S x + HjO + C0 2 = CaCO s + H 2 S 4- Sx. 6 
2. CaS.Sx + 2 HC 1 == CaCl 2 + H 2 S + Sx- 
6 Evidence that carbonic acid completely decomposes the sulphids in solution can be obtained by testing 
the solution at the end of the experiment with sodium nitroprussid. 
