H. Vohl recommends the following as the best method of detecting
sulphur in organic compounds: The substance to be tested is heated in
a solution of caustic lime and oxide of lead in glycerin. The latter
is prepared as follows: One volume of distilled water is mixed with
2 volumes of pure glycerin and heated to boiling; freshly prepared
slaked lime is added, little by little, until it is saturated. Freshly
precipitated hydrated oxide of lead, or moist litharge, is added in
excess, and the liquid allowed to boil gently for a few minutes,
then tightly corked and left to cool, after which the clear liquid
is decanted from the sediment into a glass vessel that can be tightly
corked. If into this solution be introduced and heated any organic
which contains sulphur, like hair, feathers, horn, albumen, and the
like, it will at once turn black from the formation of sulphide of
lead. The great delicacy of this test is evident from the fact that,
when pure wheat bread is boiled with this reagent, it turns yellow at
first and then dark gray in consequence of the presence of sulphur in
the gluten of the bread.
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