S

ULPHUR, a non-metallic element known subterranean beds, having an average thickness

from very early times, and proved to be of 125 feet, and covered by about 90 feet of an element by Lavoisier, in 1772. It was soft rock (mainly gray limestone) and 375 feet

not definitely admitted to the list of rec- of clay, sand and gravel. The deposits were ognized elements, however, until after the re- first discovered in 1865, and between 1868 and searches of Gay-Lussac and Thénard, in 1809. 1895 many unsuccessful attempts were made In the free state, it occurs native in many parts to work them commercially by ordinary methof the earth, usually in volcanic regions or in ods of mining. Herman Frasch, an American connection with gypsum and other allied rocks. petroleum, expert, then undertook a careful Until within recent years the commercial sup- study of the subject, and worked out a method ply has been obtained largely from Sicily, of mining the sulphur that has proved emithough a considerable quantity has been ob- nently successful. The entire practicability of tained from the Chilean Andes, and from cer- the Frasch process was first established in tain parts of Mexico, China, Japan, India and 1903, in which year 35,000 tons of sulphur were the Philippine Islands. The large deposits of brought to the surface by means of it. The southern Utah are also mined, but the American essential ideas of the Frasch process are (1) supply is now obtained almost wholly from the the use of highly heated water to melt the sulextensive deposits in and near Calcasieu Parish, phur as it lies in its bed, and (2) the use of La. Four general methods have been employed compressed air to force the molten sulphur to for separating sulphur from the stony and earthy the surface of the ground. Several concenimpurities with which it is usually associated in trically-arranged steel pipes are driven into the nature. (1) The (ore) containing it may be ground, and highly superheated water is forced heated to a temperature high enough to melt down into the sulphur bed through the outer the sulphur and permit it to run out at the bot- ones. The sulphur is thereby melted, and as tom; or (2) the ore) may be heated still more it is considerably heavier than water it collects strongly, so as to cause the sulphur to volatilize in a subterranean pool, into which the pipe and pass away in the form of vapor; or (3) system dips. Air, compressed to a pressure of the Wore may be lixiviated with a fluid (such about 250 pounds to the square inch, is forced as carbon disulphide) in which the sulphur is down the central pipe (which is one inch in soluble, the sulphur being afterward recovered diameter), and as this air returns to the surby evaporating the solvent. (4) The Frasch face of the ground through the annular space process, specially developed in connection with between the inner pipe and the next one to it, the Louisiana deposits, is described below. the melted sulphur is carried upward at the The method by melting is almost exclusively same time. When the operation is properly used in extracting sulphur from the inert mate- conducted the melted sulphur and hot water rial with which it is associated in nature, the can be kept separate, so that when the sulphur volatilization and solution methods being re- reaches the surface it is only necessary to run served for the subsequent purification of the ii into bins to cool and solidify. The product product as first obtained by melting. When that is obtained in this way is remarkably free the sulphur is extracted from an "ore, the from impurities. In fact it is not uncommonly heat required for melting it and isolating it is 99.9 (and sometimes even 99.98) per cent pure, obtained by various means. In some regions and hence it does not require further purifiit is obtained by burning a part of the sulphur cation for technical use. For a good techitself. This method is wasteful in sulphur, but nical description of the Frasch process, consult it can be put into practice very simply, and Thorpe's Dictionary of Applied Chemistry, hence its application does not call for skilled article «Sulphur." labor. In Nevada and California, and, to a Iron pyrites (native yellow sulphide of more limited extent, in Italy and Sicily, the iron) is utilized quite extensively as a source Core) is heated by steam under a pressure of of sulphur in certain lines of manufacture, 70 pounds or more; the yield by this method but the sulphur of the pyrites is rarely won being considérably greater, though the expense in the elementary form. Almost invariably the of treatment is also much greater.

sulphur dioxide that is obtained by roasting In mining the Louisiana deposits a special the pyrites is used in the preparation of sulmethod is used, which merits separate descrip- phuric acid or other compounds, without being tion. These vast deposits occur in the form of reduced to sulphur,

S

a

ULPHUR, a non-metallic element known subterranean beds, having an average thickness

from very early times, and proved to be of 125 feet, and covered by about 90 feet of an element by Lavoisier, in 1772. It was soft rock (mainly gray limestone) and 375 feet

not definitely admitted to the list of rec- .of clay, sand and gravel. The deposits were ognized elements, however, until after the re- first discovered in 1865, and between 1868 and searches of Gay-Lussac and Thénard, in 1809. 1895 many unsuccessful attempts were made In the free state, it occurs native in many parts to work them commercially by ordinary methof the earth, usually in volcanic regions or in ods of mining. Herman Frasch, an American connection with gypsum and other allied rocks. petroleum expert, then undertook a careful Until within recent years the commercial sup- study of the subject, and worked out a method ply has been obtained largely from Sicily, of mining the sulphur that has proved emithough a considerable quantity has been ob- nently successful. The entire practicability of tained from the Chilean Andes, and from cer- the Frasch process was first established in tain parts of Mexico, China, Japan, India and 1903, in which year 35,000 tons of sulphur were the Philippine Islands. The large deposits of brought to the surface by means of it. The southern Utah are also mined, but the American essential ideas of the Frasch process are (1) supply is now obtained almost wholly from the the use of highly heated water to melt the sulextensive deposits in and near Calcasieu Parish, phur as it lies in its bed, and (2) the use of La. Four general methods have been employed compressed air to force the molten sulphur to for separating sulphur from the stony and earthy the surface of the ground. Several concenimpurities with which it is usually associated in trically-arranged steel pipes are driven into the nature. (1) The (ore) containing it may be ground, and highly superheated water is forced heated to a temperature high enough to melt down into the sulphur bed through the outer the sulphur and permit it to run out at the bot- ones. The sulphur is thereby melted, and as tom; or (2) the (ore) may be heated still more it is considerably heavier than water it collects strongly, so as to cause the sulphur to volatilize in a subterranean pool; into which the pipe and pass away in the form of vapor; or (3) system dips. Air, compressed to a pressure of the "ore may be lixiviated with a fluid (such about 250 pounds to the square inch, is forced as carbon disulphide) in which the sulphur is down the central pipe (which is one inch in soluble, the sulphur being afterward recovered diameter), and as this air returns to the surby evaporating the solvent. (4) The Frasch face of the ground through the annular space process, specially developed in connection with between the inner pipe and the next one to it, the Louisiana deposits, is described below. the melted sulphur is carried upward at the The method by melting is almost exclusively same time. When the operation is properly used in extracting sulphur from the inert mate- conducted the melted sulphur and hot water rial with which it is associated in nature, the can be kept separate, so that when the sulphur volatilization and solution methods being re- reaches the surface it is only necessary to run served for the subsequent purification of the it into bins to cool and solidify. The product product as first obtained by melting. When that is obtained in this way is remarkably free the sulphur is extracted from an "ore, the from impurities. In fact it is not uncommonly heat required for melting it and isolating it is 99.9 (and sometimes even 99.98) per cent pure, obtained by various means. In some regions and hence it does not require further purifiit is obtained by burning a part of the sulphur cation for technical use. For a good techitself. This method is wasteful in sulphur, but nical description of the Frasch process, consult it can be put into practice very simply, and Thorpe's Dictionary of Applied Chemistry,' hence its application does not call for skilled article «Sulphur.” labor. In Nevada and California, and, to a Iron pyrites (native yellow sulphide of more limited extent, in Italy and Sicily, the iron) is utilized quite extensively as a source Core) is heated by steam under a pressure of of sulphur in certain lines of manufacture, 70 pounds or more; the yield by this method but the sulphur of the pyrites is rarely won being considerably greater, though the expense in the elementary form. Almost invariably the of treatment is also much greater.

sulphur dioxide that is obtained by roasting In mining the Louisiana deposits a special the pyrites is used in the preparation of sulmethod is used, which merits separate descrip- phuric acid or other compounds, without being tion. These vast deposits occur in the form of reduced to sulphur,

SULPHUR, MEDICAL USES OF - SULPHURETTED HYDROGEN

a

quantities in the manufacture of sulphuric acid through cool water, and the steam that they to remove the arsenic which is found in larger contain is condensed and the sulphur dioxide or smaller percentage in all acid made from removed by solution, a supply of pure oxygen pyrites. It is also used to precipitate copper gas is obtained. Pure anhydrous sulphuric acid from solutions containing salts of copper, and has a specific heat, at ordinary temperatures, of for precipitating gold and silver from sweep- about 0.34, and coefficient of expansion ings and other waste material. In the chemist's (Fahrenheit scale) of about 0.000310. The conlaboratory it is one of the most valuable centrated acid is a powerfully corrosive poison, reagents.

destroying organic tissues rapidly, and even SULPHURIC ACID, or OIL OF VIT- charring paper and wood. It is also poisonous RIOL, a common and exceedingly important

(though far less violently so) when adminisoxy-acid of sulphur, having the chemical

tered in any considerable quantity in a highly

dilute form. Concentrated sulphuric acid has formula H.SO.. It was first prepared by Geber, in the 8th century, by distilling aluni; and in

a powerful affinity for water, its combination the 15th century it was manufactured by burning

with water being attended by the evolution of a sulphur with saltpetre, though the identity of

large amount of heat. The strong acid is used the product so obtained with that described by as a drying agent, for removing moisture from Geber was not established until near the end

gases. For this purpose it is sometimes suffiof the 16th century. Considerable quantities

cient to allow the gas to stand for a time in a of sulphuric acid were formerly manufactured

receiver containing a dish of the concentrated by the distillation of ferrous sulphate, the prac

acid; but a more effective mode of procedure tice of this method dating from the early part

consists in passing the gas through tubes that of the 18th century. At the present time prac

are partially filled with fragments of pumice tically all of the sulphuric acid that is used

that have been wetted with the acid. is prepared from sulphur dioxide gas, either by

Chemically, sulphuric acid is dibasic, either the chamber process, or by the more recently

or both of its hydrogen atoms being replaceperfected "contact process,"" both of which are

able by metals or other bases, the compounds described in this article.

that are thus formed being termed "sulphates." When pure and free from water, sulphuric

With the metals of the alkalis (which are acid is a colorless liquid with an oily appear

monovalent), sulphuric acid therefore forms two ance, and a specific gravity of 1.89. It may

kinds of sulphates, which may be sufficiently be readily frozen, the solidified acid melting

illustrated by the potassium salts. If one of again at 50.9° F. It exhibits the phenomenon the hydrogen atoms of the acid is replaced by of surfusion to a marked extent, and the liquid potassium, the resulting salt, HKSO., is called acid can be cooled, much below the melting

(hydrogen potassium sulphate, or (acid popoint here given, without inducing solidifica

tassium sulphate”; while if both are replaced, tion; but if a crystal of the solid acid, or a the resulting salt has the formula K.SO., and small amount of sulphur trioxide, be added to

is known as “normal potassium sulphate.” Many the supercooled Auid, crystallization begins at

of the sulphates of the metals occur native once, and the temperature rises until it becomes in large quantities, and many of them are of 50.9° F., after which no further solidification great value in the arts. Those that are of

The presence of a trace of water in especial importance are described, in this enthe acid lowers the freezing point nearly to 32° cyclopedia, under the metals (or other bases) F. If five parts (by weight) of sulphuric acid

with which the acid is combined. The sulphate be mixed with nearly one part of water, and

of barium is perhaps the most insoluble salt the solution is cooled by a freezing mixture,

known. It is formed whenever a soluble a definite hydrate of sulphuric acid, having the

barium salt (such as the chloride) is added to a composition H2SO, + H2O, crystallizes out at solution of a soluble sulphate; and its forma45° F. Another solid hydrate, having the com

tion constitutes a valuable test for sulphuric position H,SO. + 4H,0, may also be prepared

acid and the sulphates. See CHEMICAL by cooling, to a much lower temperature, a

ANALYSIS mixture of sulphuric acid and water, containing When sulphur trioxide is dissolved in anhy57.6 per cent of water. Several other hydrates drous sulphuric acid in the proportion of one are also believed to exist, and special study has molecule of the trioxide to one of the acid, a been expended upon them, on account of their definite compound having the formula H2S,O: importance in the illustration of the "hydrate (or H2SO4SO3) is obtained. When pure, this theory of solutions. ( (Consult Mendeléeff, substance is known as "pyrosulphuric acid.” Principles of Chemistry," Vol. II). Sulphuric It is a dibasic acid, forming salts which are acid has no really definite boiling point. It termed "pyrosulphates, but which are of combegins to boil at about 550° F., the distillate paratively little practical importance. Pyrocontaining sulphuric acid, water and sulphur Sulphuric acid forms large crystals, which melt trioxide. (See SULPHUR). The temperature

at 95° F., and it is easily decomposed by heat of the liquid may be raised to 640° F., how- into ordinary sulphuric acid and free sulphur ever, before a state corresponding in definite- trioxide. Fuming sulphuric acid (now comness to the boiling point of water is attained, monly known in the arts as "oleum” but forthe vapor that passes off then consisting en- merely called Nordhausen oil of vitriol”) contirely of water vapor and free sulphur trioxide. sists of a mixture of pyrosulphuric acid and At higher temperatures the decomposition is ordinary sulphuric acid and may be regarded even more complete. Thus if a stream of the as a solution of sulphur trioxide in sulphuric acid be allowed to Aow over redhot bricks, it acid, the trioxide not being present in sufficient is broken up into sulphur dioxide (SO2), free quantity to convert the ordinary acid entirely oxygen and water-vapor.

If the gases

into pyrosulphuric acid. It fumes strongly in sulting from this decomposition are passed the air, gives off sulphur trioxide when heated

occurs.

re