March, I923.1 U . S . BUREAU OF MINES NOTES. 375

METALLURGICAL POSSI BI LI TI ES OF T H E DESCLOIZITE ORES AT GOODSPRINGS, N E V A D A .

By H. A. Doerner.

FOR the past three or four years attention has been attracted to the deposits of lead vanadate in the Goodsprings, Nevada, dis- trict. Some ore running as high as 9 per cent. V._,O5 has been produced, but most of it runs from o. 5 to 3 per cent. Only a little ore, and that of the richer sort, has been shipped.

It has been estimated that the district is capable of producing twenty-five tons per day of ore averaging from 2 per cent. to 3 per cent. V,,O:,. Since ore of that grade and character will not stand the cost of shipment or of chemical refining, a concentrating mill is essential to any plan for the exploitation of the deposits.

Experiments on table concentration of the ore indicate that ordinary classification and tabling of the ore and treatment of the slimes on a special canvas table will extract at least 7 ° per cent. of the lead and vanadium content and yield a concentrate contain- ing ~o per cent. V20~ and over 3 ° per cent. Pb.

No practical method, either mechanical or chemical, was found which would reduce the loss of metals in the slimes below 15 per cent. of the total amount.

The Io per cent. V~.O.~ concentrate will stand the costs of ship- ment and the extraction of the lead and vanadium, but on account of its unusual nature, there may be difficulty in finding a satis- factory market. If such is the case, the concentrate may be profit- ably refined by smelting to remove the lead and reduction of the vanadium bearing slag to ferro alloy by means of silicon: or the lead may be separated by a reducing caustic fusion and the vana- dium leached from the slag and precipitated as vanadie acid. The latter method is to be preferred on account of the uniformly high extraction and the high-grade product. Further details are given in a recent report issued by the bureau.

EFFECT OF CARTRIDGE D I A M E T E R ON T H E STRENGTH A N D S E N S I T I V E N E S S OF CERTAIN HIGH E XPL O S IVE S .

By Spencer P. Howell and J. E. Crawshaw.

ONE of the most important problems in mental mining, tunnel- ing or quarrying, is the most economical method of bringing down the ore or rock. The two factors having great influence in deter- mining this are drilling and blasting costs.

376 U . S . BUREAU OF ~'IINES NOTES. [J. F.I.

The bureau's attention has been called to the lack of definite data on the effect of cartridge diameter on the strength and sensitiveness of high explosives. This information is especially valuable to the user of explosives as it assists him in determining what diameter of borehole is most economical.

The Bureau of Mines, in co6peration with the Institute of Makers of Explosives, has carried out a series of tests to show the effect of cartridge diameter on the strength and sensitiveness of certain high explosives.

The explosives chosen for the tests are those very extensively used in metal mining, tunneling and quarrying, namely, 4o p e r cent. strength L. F. gelatin dynamite, 6o per cent. strength L. F. gelatin dynamite and 4o per cent. strength ammonia dynamite.

The tests carried out have shown conclusively, ( I ) That both the rate of detonation and sensitiveness to

explosion by influence increase with the increase in diameter of cartridge.

(2) That gelatin dynamites rapidly decrease in sensitiveness to detonation and explosion by influence on aging while the ammonia dynamite was very little affected.

(3) That the insensitiveness of gelatin dynamites to detona- tion and explosion by influence on aging proceeds more rapidly the smaller the diameter of cartridge.

(4) That the insensitiveness to detonation and explosion by influence proceeds more rapidly with 6o per cent. strength L. F. gelatin dynamite than with 4o per cent. strength L. F. gelatin dynamite. Further information will be found in the report on this subject recently published by the bureau.

A New Amplifier of Sounds. L. GAUMONT. (Comptes Ren- dus.)--Many amplifiers of sound distort it without mercy. It is claimed that the following device is free from this defect. The vibrat- ing part is a cone of fine silk fabric around which is wound a spiral of fine aluminum wire in one or more layers. The angle of the cone is 90% This is introduced into the space between the pole pieces of an electromagnet which have the same angle. The cone fits over one of these. When telephonic currents are sent through the aluminum wire there are forces exerted upon the latter by reason of the interaction between its magnetic field and that of the electro- m~ignet. Since the spiral has no natural period of its own, it does not reproduce the sound with distortion. Great distinctness is claimed as well as great intensity. G . F . S .