206 GRAVEL AND PLACER MINING IN ALASKA. [bull. 263. 
In melting, a gasoline 2-jet furnace may be used. Gasoline under 
a pressure of 30 pounds enters a heating coil attached to the burner. 
The heating coil is so arranged and fed that liquid gasoline burning on 
the outside of the main feed vaporizes the gasoline which is used 
within the furnace. With the 30 pounds pressure used a very hot 
flame is the result. The gasoline supply should be stored without the 
building and brought in through pipes, so as to reduce the danger of 
explosion. An air barrel connected with the supply line and supplied 
Avith a small hand pump serves to keep the gasoline pressure as high 
as may be necessary. The furnace is made of sheet iron and lined with 
fire brick. A cover of asbestos and iron serves to retain heat. This 
should be so constructed as to allow the bolting on of new iron plates, 
as they burn off with the great heat generated. The operator should 
be supplied with asbestos gloves. 
Crucibles are of various sizes. A No. 30 crucible, costing between 
$2 and $2.50, will hold from 900 to 1,000 ounces of impure gold or 
bullion with the necessary fluxing charge. They are composed of a 
mixture of line clay and graphite, and to prevent breaking certain 
precautions should be observed. A new crucible should stand near 
the furnace, at least during two melts, and when first used should be 
heated gently. This precaution is not necessary when a crucible has 
once been used. • After a crucible has been used five or six times it can 
not be depended on and it would be economy to discard it, as breaking 
during a melt is a source of great inconvenience and loss of time. 
It is necessary to have an iron table near the furnace, upon which 
can be placed gold pans, shovels, tongs, etc. 
Before the gold is placed in the crucible it should be accurately 
weighed and cleaned with a magnet, as above described. 
In melting 900 to 1,000 ounces, three-fourths of a pound of borax 
should first be melted in the crucible as a flux. After the dust is : 
poured in, one-fourth pound of soda with one-half pound of borax 
should be placed on top. The soda unites with the silica of the sand, 
but in perfectly clean gold is not needed. The borax unites with the 
iron occurring with the gold. When the dust is mixed with consider- 
able iron pyrite it is well to add a small quantit}^ of scrap iron. This, 
in uniting with the sulphur, forms iron sulphide, which comes off in 
the slag. If this precaution be not taken a hard matte, very difficult 
to remove, forms upon the brick. 
During the melt it is necessary several times to skim the slag from the 
gold. A special instrument is used for this purpose, essentially a long 
rod bearing at its lower end an enlargement to which the slag will stick. 
After gathering a small quantity upon the skimmer it is brought 
out, and by rolling on the iron table is made into a smooth, disk- 
shaped mass upon the end of the rod. This operation is continued 
until the slag collected upon the skimmer becomes unwieldy, when it^ 
is cooled by plunging it in water and broken off. When the gold is 
