May 24, 1901.] 
it is used for the production of very high 
temperatures in the electric furnace. In 
simple form the electric furnace consists of 
a box made of fire bricks in which the carbon 
poles of an electric are light are placed. 
Under the influence of the high tempera- 
tures produced between the carbon pencils 
nearly all metal oxides are reduced by car- 
bon. Aluminium oxide is reduced in this 
way at Niagara Falls, and aluminium 
bronze, an alloy of aluminium and copper, 
is made. Sand isreduced inthe same way, 
and the element silicon unites with the ex- 
cess of carbon and forms the compound car- 
borundum, an exceedingly hard substance 
which is used so extensively as a substitute 
for emery. Artificial graphite and phos- 
phorus are also made in the electric fur- 
nace and the carbides of a large number of 
metals have been prepared. Of these car- 
bides calcium carbide has become of com- 
mercial importance, as it is used extensively 
for making acetylene. 
The other way in which the electric cur- 
rent is utilized is for the electrolysis of 
liquids, either solutions of substances in 
water or fused substances. At Niagara 
metallic sodium is now made by the elec- 
trolysis of fused caustic soda. One of the 
uses of the metallic sodium is to prepare 
sodium peroxide, the new bleaching agent, 
for which purpose the metal is burnt in 
dry air. Metallic aluminium is obtained by 
the electrolysis of aluminium oxide in a 
fused bath of cryolite. Caustic soda and 
chlorine are made by the electrolysis of 
salt solutions, and potassium chlorate by 
the electrolysis of potassium chloride solu- 
tion. The electric current is also used in 
refining certain metals, for which purpose 
sheets of the crude metal are suspended at 
one pole in a bath of the metal salt and the 
pure metal deposited at the other pole. 
During the past century great progress 
has been made in the methods of extract- 
ing the metals from their ores. Not only 
SCIENCE. 
807 
has this been true of iron, but of all the use- 
ful metals. As an example, it is only nec- 
essary to call attention to the cyanide proc- 
ess of extracting gold and silver. Gold 
and silyer ores which are so poor that it 
was unprofitable to work them in previous 
years are now successfully treated with 
a solution of potassium cyanide, which has 
the power, in the presence of air, of dis- 
solving the noble metals. Itis this method 
which has largely contributed to the in- 
creased production of gold in recent years. 
Side by side with this improvement of 
metallurgical processes has gone the util- 
ization of by-products. Not only is blast- 
furnace slag used in making Portland cem- 
ent, but other slags, such as those ob- 
tained in the basic steel process and which 
contain phosphoric acid, are used as fertiliz- 
ers. The sulphur dioxide formed by roast- 
ing lead and zinc ores is no longer allowed 
to escape into the air, but is converted into 
sulphuric acid. 
PROGRESS IN ORGANIC CHEMISTRY. 
But undoubtedly the most rapid strides 
in the development of chemistry have been 
made in the past century in that depart- 
ment known as organic chemistry. One 
hundred years ago our knowledge of the 
compounds occurring in the organs of plants 
and animals was very meager indeed. A 
few organic substances had been isolated, 
but their composition was very imperfectly 
known, as the methods of analysis were 
very crude. Liebig in 1830 improved the 
method of analyzing these compounds and 
thus laid the foundation of organic chem- 
istry. 
A century ago it was generally believed 
that organic compounds could not possibly 
be made artificially by synthesis in the 
laboratory, as was the case with mineral 
compounds. It was thought that a peculiar 
vital force in some way intervened in their 
production in the organs of plants and 
. 
