Page:Popular Mechanics 1928 01.pdf/80

 experts employed by the government of California that natural treasure, beside which that taken by the dredges is trifling, is still lying in the gravel deposits of the state. From 1853 to 1909, it is stated, $1,200,000,000 in gold was produced by hydraulic and placer-mining methods from the river beds, old and new. State engineers believe that there are at least fifty, and probably one hundred, surface and buried-river gravel beds which never have been touched by miners, though their gold content may be too low for profitable working.



 

Chemists have developed a new treatment for rubber goods, to prolong the life of the material by counteracting the effect of oxygen. Experts declare that some rubber articles would last almost indefinitely were it not for the results of oxidation from the air. Tires, for instance, suffer a serious loss in tread abrasion, owing to this process. Besides offsetting the action of oxygen, the new substance is said to counteract the effect of high temperatures, which is of importance regarding bus and truck tubes, often exposed to heat and air at once.

 



For boiling eggs up to five minutes, a timer operated by a sandglass has been introduced. It can be set for almost any interval under five, and as the sand runs into the lower glass, the weight causes the tube to descend. This releases another weight at the proper time, and a bell rings, announcing that the eggs are done.

