COMPOSITION" OF LIMB-SULPHUR ANIMAL DIPS. 9 
To eliminate the disturbing effect of hydrolysis which had evidently occurred, 
Preparation N was made by charging 20 grams sulphur and slaked lime equiv- 
alent to 9 grams available calcium oxid into a 4-ounce sample oil bottle, which 
was then filled with water and sealed. For some weeks the bottle was shaken 
by machine several hours each working day, but the action was so slow that 
finally it was simply given a brief shaking by hand once or twice a day. After 
42 days a sample of the clear liquid, diluted to 2 volumes, showed the molecular 
ratio M 2 Sx : M 2 S 2 03=1.92. 
The last preparation suffered a slight exposure to air while the necessary 
degree of dilution for analysis was being ascertained. To get further light on 
the possibilities Preparation O was similarly made, but using only 10 grams 
sulphur and employing a slight calculated excess of caustic soda solution in- 
stead of lime. In 5 days the sulphur was entirely dissolved, and on the next 
day a 4-volume dilution showed the molecular ratio M 2 S* : M 2 S 2 3 =1.93. The 
dilution had been prepared by pipetting 25 c. c. into a 100 c. c. volumetric flask 
about half full of water, then making to the mark. The diluted solution was 
filled into 15 c. c. glass-stoppered bottles, one of which was used for each test. 
Freshly boiled water was used for the original preparation and for the dilution. 
From Experiment 8 it is evident that the fundamental reaction 
between lime and sulphur is parallel to that between caustic soda and 
sulphur and it must be assumed that two molecules of polysulphid 
are produced for each molecule of thiosrlphate. The analytical 
methods are not known to be at fault except in a minute error of 
end-point, arising from the necessity of obtaining the sulphid-acid 
figure by subtraction. The chief cause of the failure to reach the 
theoretical ratio must, therefore, be oxidation during the manipu- 
lation of the solutions. An oxidation of 1 per cent of the mono- 
sulphur to thiosulphate by calculation would produce a drop in the 
ratio from 2.00 to 1.94. 
LOWER POLYSULPHIDS; EFFECT OF EXCESS OF LIME. 
The composition of the crystalline polysulphid which sometimes 
forms in a solution prepared with excessive lime has received consid- 
erable previous study with conflicting results. 8 It seems, however, to 
have been proved to be a basic polysulphid which is decomposed 
when treated with water into calcium hydrate and a soluble calcium 
polysulphid that was first stated by Schone to be tetrasulphid. For 
present study the composition of the crystals themselves is imma- 
terial, since we are only concerned with polysulphids in solution. 
So far as work subsequent to Schone has covered the question it has 
only served to confirm his observations and to strengthen the hy- 
pothesis that tetrasulphid is the lowest polysulphid ever occurring 
in a lime-sulphur solution. Only the following experiment was, 
therefore, thought necessary. 
EXPERIMENT 9. 
Preparation P, originally intended to follow Preparation E in Experiment 
3, was made on the formula 70 : 100 : 521, boiling for one hour. After standing 
