78 WOLFRAM FROM BATANG PADANG. 
The following extract from the Exglish Mechanic gives some in- 
teresting details respecting the metal and its uses. 
“Tungsten belongs to a group of rare metals, and until a com- 
paratively recent time was known only to the chemist, and its value 
was known only in the laboratory. 
“With the invention of 1oo-ton guns the demand for tungsten soon 
made the previously obscure metal well known throughout the mining 
world. It was soon found that the steel tube lining the bore of these 
enormous guns could not resist the shock entailed by discharging many 
shots without becoming fractured. Experiment proved that the addition 
of a small quantity of tungsten to the fine steel employed in gun-making 
rendered the latter metal wonderfully elastic, so that the steel tube will 
expand under the tension of firing and contract again to its normal size 
a great many times before the quality of the metal is in any way impaired. 
The German gun factories absorb most of the tungsten found in the 
world, and from being a mere curiosity seen only in the laboratory of the 
chemist, this rare metal has acquired considerable value. Wolfram 
generally occurs in combination with iron in Europe, but it is also found 
in scheelite, or tungstate of lime. It is in the latter form that it occurs 
in Otago (New Zealand). The metal itself is of a white colour, extremely 
brittle and heavy, the specific gravity being 1g‘t, that of gold being 19.3. 
It will thus be seen that tungsten is a very heavy metal, being only very 
slightly lighter than gold.” 
