US 1925641 A
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Patented Sept. 5, 193g PRODUCING IGNITIBLE COMPOSITION 7 Stanley. Hector Lucas, Witton, Birmingham, V England, assignor to Imperialv Chemical lindnstries Limited, a corporation of Great Britain No Drawing. Application July 7, 1932, Serial No,
LIGHT 621,314, and in 1931 This invention relates to improvementsin com positions which when ignited emit albrilliant light and which consist of a metallic powder mixed with an oxidizing agent. such'compositions consist essentially of one or morefinely divided metals such as magnesium, aluminium and zirconium, and oxidizing agents'such as potassium chlorate, barium nitrate, potassium nitrate,
, barium. peroxide and the like. These light producing ignitible powders find application in the art of pyrotechny, as flash powders for photographic purposes, and they are also applied for obtaining tracing effects in military and other,
forms of ammunition. The compositions hitherto used have had certain disadvantages, such as the sensitivity to shock or friction associated with those containing potassium chlorate as the oxidizing agent. Others containing barium peroxideas the oxidizing agent are unstable and suffer deterioration. when exposed to the atmosphere.
Those containing nitratesare diflicult to ignite,
and further, barium salts are toxic and therefore undesirable under certain conditions of use, e. g.v connection with tracer pellets forv shot gun:
The objects of this invention are to produce an improved light emitting ignitible composition which is not sensitive to ignition by shock or;
51 j friction, which is stable whenexposed to the at'-. mo'sphere, which is easily ignitible and non toxic. I have found thatthese objects are obtained if the oxidizing agent used in combination with the metallic powder is bismuth oxide or sodium bismuthate or mixtures of these two compounds.
'35 Sodium bismuthate is. an oxidizing agent and details of its preparation and properties are given 7 in volume 9 of Mellors Comprehensive Treatise on Inorganic and Theoretical Chemistry. I Bismuth oxide is preferable, to sodium bismuthate since experience has shown that the compositions containing sodium bismuthate,- although stable in ordinary atmospheres, are apt to be aiTected by excess of moisture or exposure to a humid atmosphere for long periods. It appears that under these conditions the sodium bismuthate reacts with the metallic powder, e. g. magnesium, and the ignitibilityof the composition is thereby impaired. Bismuth oxide, how- 5 ever, does not behave in this way.
" It has'also been found that the metallic pow- Great Britain October 21,
7 Claims. (01. 52 24) I ders themselves tend to deteriorate when exposed to moisture for long periods and that it is therefore desirable, in order to obtain an absolutely reliable product, topack the same'in air-tight containers. Accordingly, in the manuiacture'of tracer pellets for ammunition, the composition Jmay be pressed into moisture-proof capsules, the
open ends of which are sealed by means of metal foil so that the pellets arecompletely' air and moisture tight.
As an example of one improved light emitting composition prepared in accordance with the invention, I may mention a mixture of two parts of magnesium powder and three parts of bismuth oxide, which when pressed under a load of ten cwts. into tracer pellets for shot gun cartridgesgives excellent results, having the desired properties of certainty of ignition, brightness of trace, and freedom from danger of possible toxic efieots. Similar resultsare obtained with a mixture of one part magnesium powder and one to two parts of sodium bismuthate.
As a 'further example Ifmay mention a composition containing three parts of bismuth oxide,
. two parts of magnesium powder or other suitable metallic powder, and half a part of strontium v peroxide. -The addition of the strontium peroxide changes the'white colour of the flame emitted :by the tracing composition'to a reddish, colour and in brilliant sunlight thetrace is much more 'disce'rnible than a completely whitelight.
While I have referred principally to the use of the improved compositions in connection with tracer pellets for shot gun cartridges, it is to be understood that they are also applicable for a Variety of other purposes such as those mentioned 4. A light-emitting ignitible composition comprising magnesium powder and bismuth oxide.
5. A light-emitting ignitible composition comprising magnesium powder and sodium bismu- I thate. V
1 6. A light emitting ignitible composition consisting of two parts by weight of magnesium powder and three parts of bismuth oxide.
7. A light-emitting ignitible composition consisting of one part by weight of magnesium powder and 1-2 parts of sodium bismuthate.
v STANLEY HECTOR,'LUCAS.