New applications for Gallium
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460 CURRENT TOPICS. [J. F. 1. on an up-draft; down-draft or both combined. The water supply is regulated by a needle valve and is allowed to flow either into a vaporizer above the refractory or into the annular space around the base depending upon whether a down or up-draft is used. The generator is operated by engine suction. To start it, a fire is lighted with sticks and after a few minutes the hopper filled with coke. If the engine must be cranked it is well to start if off with gasoline; if provided with a self starter the engine can be started directly on gas. The most desirable type of fuel should have a relatively high volatile content, low moisture and low ash. Low temperature coke has proved eminently suitable for these reasons. Wood charcoal also makes a good fuel. The engine is provided with a special cylinder head giving a compression ratio between 6 and 7 to I. The designer estimates fuel consumption to be 63 pounds per Ioo miles while 0.85 gallons of water are used for the same distance. T. K. C. A New Principle in Grinding.--( Chemistry and Industry. Feb. I2, I932 ). A grinding mill whose design represents a new departure from the usual type. The principle under which most grinding and pulverizing mills operate is that of exerting friction upon the ma- terial. This is usually accomplished by passing it between closely spaced moving surfaces which at the same time exert a considerable pressure. In contrast to this method, classed as pulverization by grinding and retention this new mill pulverizes by shattering and ejection. Its grinding elements consist of rows of free swinging hammers fastened between a series of discs attached to the shaft of the mill. These hammers are cast from high tensile manganese steel so tough and hard it cannot be machined. The mill operates through the medium of these swinging hammers which shatter the material in mid-air. In such a mill friction is practically eliminated. Accidental addition of large, hard objects to the mill will not result in the damage so often experienced with the present type since the hammers can freely swing back into the spaces between the discs. T. K. C. New Applications for GaUium.--(News Edition, Industrial and Engineering Chemistry.) The element Gallium was discovered in I875 by Lecoq de Boishandran. This silver-white metal melts at about 3°0 C. and boils around 2000 ° C. Gallium is comparatively rare and until recently a unit which now costs $8.70 sold for $I75. This cheapened method of preparation has been worked out by a German firm.
Transcript of New applications for Gallium
460 CURRENT TOPICS. [J. F. 1.
on an up-draft; down-draft or both combined. The water supply is regulated by a needle valve and is allowed to flow either into a vaporizer above the refractory or into the annular space around the base depending upon whether a down or up-draf t is used. The generator is operated by engine suction. To start it, a fire is lighted with sticks and after a few minutes the hopper filled with coke. If the engine must be cranked it is well to start if off with gasoline; if provided with a self starter the engine can be started directly on gas. The most desirable type of fuel should have a relatively high volatile content, low moisture and low ash. Low temperature coke has proved eminently suitable for these reasons. Wood charcoal also makes a good fuel. The engine is provided with a special cylinder head giving a compression ratio between 6 and 7 to I.
The designer estimates fuel consumption to be 63 pounds per Ioo miles while 0.85 gallons of water are used for the same distance.
T. K. C.
A New Principle in Grinding.--( Chemistry and Industry. Feb. I2, I932 ). A grinding mill whose design represents a new departure from the usual type. The principle under which most grinding and pulverizing mills operate is that of exerting friction upon the ma- terial. This is usually accomplished by passing it between closely spaced moving surfaces which at the same time exert a considerable pressure. In contrast to this method, classed as pulverization by grinding and retention this new mill pulverizes by shattering and ejection. Its grinding elements consist of rows of free swinging hammers fastened between a series of discs attached to the shaft of the mill. These hammers are cast from high tensile manganese steel so tough and hard it cannot be machined. The mill operates through the medium of these swinging hammers which shatter the material in mid-air. In such a mill friction is practically eliminated. Accidental addition of large, hard objects to the mill will not result in the damage so often experienced with the present type since the hammers can freely swing back into the spaces between the discs.
T. K. C.
New Applications for GaUium.--(News Edition, Industrial and Engineering Chemistry.) The element Gallium was discovered in I875 by Lecoq de Boishandran. This silver-white metal melts at about 3 °0 C. and boils around 2000 ° C. Gallium is comparatively rare and until recently a unit which now costs $8.70 sold for $I75. This cheapened method of preparation has been worked out by a German firm.
April, I932. ] CURRENT TOI'~CS. 461
Gallium already has been recommended in this count ry as a filler for quartz thermometers to be used for high temperatures around 500 ° to IOOO ° C. Gallium readily forms alloys and as such may be used for brightening optical mirrors, and as a subst i tute for amalgam in filling teeth. Gallium should find application in metallic vapor lamps for unlike mercury it gives a spectrum ex- tending into the infra-red region.
T. K. C.
The Exploding W e d g e . - - T h e Du Pont Magazine for Feb. r932 describes an innovation in wedges which greatly reduces the labor usually involved in splitting logs of very tough and cross-grained wood. The steel wedge is fitted with a handle inside which is a small strong-walled chamber. In addition, there is a hole through the thicker end of the wedge and into this space the opening of the chamber passes. To operate, the hollow of the handle is loaded with a small charge of black powder, the wedge driven into the log up to the hilt, then a fuse is a t tached and lighted, . . . . The log is split wide open.
T. K. C.
High Chromium S tee l s . - - In a paper, " High Chromium Steels in the Chemical Indus t ry " (Chemistry and Industry,, Vol. 5 I, No. 3, 1932) DR. F. M. BECKET reviews the progressive changes in the consti tut ion of these steels as a t tempts have been made to discover the most suitable composition for this or tha t fabricating appara tus or unit.
I t is well known tha t chromium imparts to steel pronounced rust-resisting qualities by virtue of which such alloys have won the very descriptive name " stainless." The earliest commercial stain- less steels contained from I2 per cent. to 14 per cent. chromium with o.25 per cent. to o.40 per cent. carbon. These steels required a drastic quench from high temperatures in order to acquire their stainless properties. Such t rea tment also left them in a hardened condition which prevented their application in the major i ty of engineering processes.
Several years later another alloy appeared having I2 per cent. to i6 per cent. chromium with carbon as low as o.~2 per cent. This type could be rendered stainless wi thout the necessity of a drastic quench and was capable of passing through many of the ordinary processes of steel fabrication.
While chromium possesses very high resistance to oxidizing influences nickel on the other hand is particularly resistant to re-
