4 BULLETIN 102, PART 3, UNITED STATES NATIONAL MUSEUM. 
the United States is fulfilled is the actuating motive for this paper. 
The resulting expression is a review of the existing situation in the 
light of science without pretense toward an increment to the light 
itself. 
GENERAL CONSIDERATIONS. 
Inorganic nature affords sulphur in three forms of occurrence; 
namely, in the free or native condition ; in combination with one or 
more metals forming the so-called sulphide minerals; and united 
with oxygen and certain metals to form the class of minerals known 
as sulphates. The sulphides include many important ore minerals; 
indeed, a large part of the world’s output of copper, lead, zinc, sil- 
ver, nickel, antimony, mercury, and other metals is derived from 
ores which are direct combinations of sulphur with the metal in- 
volved. It therefore appears that sulphur has in the past played a 
part of great importance to the welfare of man as an essential agent 
in the geological evolution of many important ore deposits. The 
sulphates, as a class, are of far less importance industrially than the 
sulphides, though they are widespread in occurrence and bulk, and 
many of them, such as barite and gypsum, have many useful techni- 
cal applications. The sulphur industry, as treated in this paper, is 
confined to a consideration of native sulphur, as free sulphur is not 
yet won on a commercial scale from either the sulphides or sul- 
phates, owing to the superior cheapness with which it may be ob- 
tained from large and easily worked deposits of the native element. 
The sulphides, it is true, at present yield practically all the sulphuric 
acid used in this country, obtained either as a by-product in smelting 
ores of copper, lead, zinc, and silver, or directly by the roasting of 
pyrite, the commonest of all sulphides, imported largely from Spain ; 
but the sulphuric-acid industry is technically and economically quite 
distinct from the sulphur industry proper and is appropriately 
treated under a separate head, though the two industries will prob- 
ably not always remain estranged. 
Sulphur has been known from the earliest times because of its 
bright yellow color, its conspicuous occurrence in many parts of the 
world in the neighborhood of volcanoes, and the ability possessed by 
it of burning with a blue flame to form a pungent gas. Because of 
this last-named property it came to be regarded by the alchemists 
of old as the principal of combustion; and this idea is retained in 
modified form in the sjunbolical meaning that attaches to brimstone 
(the Anglo-Saxon used for sulphur) in its frequent use throughout 
English literature. 
Sulphur first sprang into world prominence in the fourteenth cen- 
tury, in consequence of the invention of gunpowder, of which it is 
an important ingredient. It has held a conspicuous place to the 
present day by virtue of the increasing use of that explosive, as well 
