US2476370A - Electric initiator device and ignition composition - Google Patents

Description

July 19, 1949. E. .1. HANLEY ELECTRIC INITIATOR DEVICE AND IGNITION COMPOSITION Filed Jan. 19, 1945 [dwara l Han/ey INVENTOR.

ATTORNEY Patented July 19, 1940 t v ELECTRIC mm'roa DEVICE IAulo IGNITION Comosrrron Edward J. Hanley, Port Ewen, N. Y., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Application January 19, 194,5, Serial No. 'l3l55y 12 Claims. l l

This invention relates to ignition compositions and more particularly to ignition compositions for use at low temperatures.

Rocket projectiles are launched by igniting theV powder in the rocket motor.

For this purpose an electric squib containing aksuitable flash mixture is customarily employed. However, in order that the rocket projectile may be aimed with accuracy, it is essential that the squib re the projectile almost instantaneously; that is, the propellant powder in the rocket should be fully ignited in the order of 0.1 second or less after closing of the electric circuit which fires the squib. In the application for U. S. Letters Patent, Serial No. 449,695, now U. S. Patent No. 2,370,159, electric squibs are described which have ignition times of about 0.3 second at ordinary and elevated temperatures. However, at

temperatures below about 54 C. the ignition time of these squibs increases to about 0.8 second or higher. The squibs ordinarily used for this purpose, containing a charge of about l gram of nely granulated black powder, meet this requirement at ordinary and elevated temperatures, but at temperatures kbelow about 54 C.

the ignition time increases, averaging around 0.3

second at -18 C. This is undesirably long, especially when the rocket projectile is to be launched at or from a rapidly moving object.

Now in accordance with this invention, electric initiators have been prepared which re rocket projectiles instantaneously not only at elevated but also at extremely low temperatures. `This has been eiected by an ignition composition comprising selenium, a metal selected from the group consisting of lead and tin, a flame-producing metal and a name-spreading agent such as an .oxidizing material or a gas-producing material 'containing an oxidizing material. This ignition mixture is adapted for use in the standard types of both vented and ventless electric lnitiators.

In general, electric initiators in accordance with this invention comprise a shell,` a. ring assembly, and the novel ignition composition. The ring assembly includes a plug which serves as the means for spacing the lead wires and holds them in dielectric relation to each other. An electrically-resistant bridge wire connects the terminal ends of the lead wires. The initiator may be made waterproof by a layer of moistureresistant compound such as asphalt or wax, and by a layer of sulfur or other sealing material. The ignition composition of this invention may be employed as the sole ash mixture in electric squibs. Preferably, however, it is used together (Cl. 1oz-2s) lead wires d to the terminal ends of which isA with a. baseI charge of ash mixture comprising a. flash-producing metal and a name-spreading agent.

and delay types.

The nature and purpose of the invention'have hash charge 2y of potassium nitrate and powdered magnesium. The ignition composition 3 superimposed upon the ash charge 2 comprises approximately 0.5 gram of a loose mixture of lead,-

selenium, magnesium, and Vpotassium nitrate. Embedded in the ignition mixture is a pair of aiiixed a bridge of electrically-resistant wire E.

'I'he -lead wires are held in position by the ignition plug 6. A layer of asphalt waterproofing compound 'i and a sulfur seal 9 held in position by crimps 8 in the shell complete the squib.

The following examples illustrate the practice of this invention.

EXAMPLE l Electric squibs were prepared according to l standard procedures employing .25-caliber aluminum shells, and electric blasting cap-type ig-l nition assemblies, containing as the sole ash mixture various formulations of an ignition com` v, position comprising lead, selenium, and powdered aluminum' and/0r magnesium. The proportions of the ingredients employed are given in Table I.

These squibs were tested in a 2.36-inch rocket held in position in a concrete block such that the gases emitted by the rocket motor were permitted to escape into the atmosphere. The sticks of smokeless powder comprising the charge for the rocket motor were inspected and weighed, then The ignition composition is also satisfactory as the ignition charge in electric blast-. ing caps or igniter fuses of both instantaneous 3 l at 18 C. and 40 C. they were used until the threads showed signs of wear.

The static ring tests were conducted at -40 C., 18 C., and at 54 C. The rocket assemblies were allowed to remain at the temperature of the tests for about 18 hours before ring ,to make certain that the interiors of the sticks of smokeless powder were at the proper temperature. The temperature was held to a tolerance of il" C. The round was red within 2 minutes after removal of the rocket assembly from the conditioning temperature. In the-18 C. test, the opening in the nozzle was closed with a cardboard disk to prevent condensation of moisture in the interior of the motor. In the -1'8 C. test 2 strain gauges which change in resistance with the pressure were used. At 54 C. 3 ball gauges which measure the maximum pressure were used in addition to these. These gauges were connected to the interior of the motor tube through a grease channel which is formed `by drilling a hole in the normally closed end of the motor tube.

A separate photographic record in duplicate was made of each shot on a strip of sensitized paper about 4 inches wide and 5 feet long, by means of a rotating drum camera. This record showed when the current was applied to the squib and the pressure at all times during the test. From this information the ignition time', pressure data, and burning time were obtained. 'I'he term ignition time designates the time elapsed between closing of the electric circuit which res the squib and the time pressure rst begins to build up due to burning of the smokeless powder in the rocket motor.

The images on the photographic record were formed by three mirror galvanometers. One of these vibrated at a known rate and thus placed timing lines on the record. Each of the other galvanometers was actuated by one of the strain gauges. Their degree of deflection was a measure of the change which in turn was a measure of the pressure. To obtain the actual pressure value, the deflection was compared to the deflection caused by unbalancing the galvanometers in steps of 1 ohm. The resistance value thus determined was then converted into pressure by means of a graph which was kept for each gauge. These galvanometers were caused to flicker when the current was applied to the squib. The time between this icker and the first appearance of pressure is therefore the ignition time. I'he total time that the system is under pressure is the measure of the burning time.

'Ihe ignition times observed in ring these squibs are shown in Table I:

The above results show that squibs having ignition compositions similar to that of this invention but, however, lacking a flame-spreading material fire rocket projectiles at fair ignition times at elevated temperatures but give very poor results at low temperatures.

Squibs exactly the same as the above were prepared containing as the sole ash mixture the same ignition composition modified by the addition of potassium nitrate as the flame-spreading agent. The proportions of the ingredients in the various formulations of Iignition mixture employed and the firing results observed when fired as described above are given in Table II.

Table II Ignition Composition 1 2 Per cent Lead 61.2 57. 8 Per cent Selenium 23. 4 22.1 Per cent Aluminum 2. 7 2. 55 Per cent Magnesium 2. 7 2. 55 Per cent Potassium Nitrate 10.0 15.0 Ignition Time (Seconds) (Average of at least 5 squib These results show that addition of a flamespreading agent, in this case an oxidizing material, yields an ignition mixture quite different in properties. Such a composition gives a squib which res rocket projectiles instantaneously not only at elevated temperatures but also at temperatures as low as 18 C.

EXAMPLE 2 Squibs were prepared and tested as described in Example 1. The ignition mixtures employed contain lead, selenium, aluminum, and/or magnesium with black powder as the llame-spreading agent.' Six formulations of ignition mixture were employed in the preparation of these squibs as shown in Table III. The squibs were fired in a static 2.36-inch rocket assembly at -40 C., 18 C., and 54 C.

The results show that black powder may be substituted for potassium nitrate in the'ignition composition of this invention without adversely affecting the ignition time.

EXAMPLE 3 When magnesium powder is employed as an ingredient of flame-producing compositions for military use, it is sometimes coated with linseed oil to protect the magnesium against moisture and reaction with chemicals which may be in contact with it. Electric squibs were therefore prepared containing uncoated and linseed oilcoated magnesium in order to determine whether the linseed oil coating had any effect upon the ignition time. These squibs each contained 2.5 grams of the ignition composition of this invention as the sole flash mixture ignited usingl an electric blasting cap-type ignition assembly. The results observed after ring the squibs in a static 2.36-inch rocket assembly as described in Example 1 are given in Table IV. It is apparent that the linseed oil coating has little effect upon ignition time.

Squibs containing each of the above ignition mixtures were stored for months at 50 C. in order to determine whether a larger ring current was required after storage. Those containing uncoated magnesium fired at 0.45 ampere before and after storage while those containing linseed oil-coated magnesium fired at 0.45 ampere before and at 0.55 ampere after storage.

EXAMPLE 4 Electric squibs were prepared employing 2% inch .25 caliber aluminum shells. In these vshells was inserted 0.8 gram of a flash mixture containing 37% magnesium and 63% potassiuml nitrate which was pressed under a pressure of 500 lim/sq. in. to a height of 'K3 inch. Upon this flash mix-` ture was placed 0.5 gram of an ignition composition containing 57.9% lead, 22.1% selenium, 7.5% magnesium, and 12.5% potassium nitrate, which was lightly pressed to a charge-height of 13/54 inch by the insertion of the ignition plug containing the lead wires and the bridge wire.- f

Twenty of these squibs were red in a' 2.36-inch rocket as described in Example 1 at -18 C. The ignition times observed ranged between 0.042 and not the plugs would pop out of the shells without rupture of the shell at low temperatures. No appreciable' lag in ignition time was found nor wlere there any signs of the shells starting of! the p ugs.

It was decided to determine the maximum charge density at which the squibs would re satisfactorilm Twenty-six squibs were therefore prepared in which the base flash charge was pressed at the maximum pressure (4000 lb./sq. in.)

possible in the charging machine. At this pressure the shell wall bulged. Twenty of these were then red in the open at -40 C. and 6 were fired in a dummy 2.36-inch rocket containing wooden sticks in place ofthe smokeless powder at the same temperature. They fired substantially instantaneously and gave complete ignition of the base charge.

Tests were conducted in order to determine whether ignition would occur if segregation of the flash mixture resulted duringor following charging. Ten squibs were prepared with' 0.06

0.052 second with an average of 0.049 second.

gram of potassium nitrate on top of the pressed flash mixture of magnesium and potassium ni trate. Fifteen additional squibs were prepared having 0.15 gram of potassium nitrate pressed to a height of 9/s4 inch placed on top of the magnesium-potassium nitrate flash mixture. These squibs were then fired in the 2.36-inch rocket. Complete ignition of the base flash mixture was obtained in each case.

EXAMPLE 5 Electric squibs were prepared in accordance with the procedure outlined in Example 4. Each of the squibs contained electric blasting cap-type plugs. The proportions of ingredients in .the various formulations of ignition composition are given in Table V. These squibs were fired in a 2.36-inch rocket according to the procedure described in Example' 1 and the ignition times observed recorded in Table V. l

The' squibs containing a magnesium-potassium nitrate 'base charge gave slightly better ignition in the open at 40 C. to determine whether or 45 times.

Table V Ignition Composition, Per cent by weight Base Charge, Per cent by weight Ignition Time, Seconds I tion Lead-Seie- Potassium Potassium Ch e o s mum 1 Mmmm Nin-sie W- Mmmm Nima weig t *18 0- 54 C- 1 84 6 10 2. 5 None None N one 0. 78 0. 068 0.086 0.094 0.082 0.076 0. 070 0. 060 Av. 0.079 Av. 0. 076 2 78 0 15 2. 5 None None None 0. 082 0. 056 0. 062 0. 070 0.078 0.060 0.080 0. 064 0.064 0. 070 Av. 0. 073 Av. 0. 062 3 68 12 .20 2.5 None None None 0.096 0.060 0. 054 0.064 0.090 0.100 0.060 0.078 0.038 0.052 0.088 Av. 0. 071 Av. 0. 071 4 60 15 25 2. 5 None N one Nona 0. 044 0. 052 0.062 0.054 0.050 0.080 0.044 0. 056 0.078 0.056 Av. 0. 056 Av. 0. 061 5 80 7.5 12.5 0.5 37.5 62.5 0.8 0.048 0.043 0.043 0. 038 0.044 0.035 0. 052 0.042 0.050 0.038 0.034 Av. 0.047 Av. 0.038

1 72.4% lead and 27.5% selenium.

Electric squibs were prepared by placing 0.8v Iram of an aluminum-potassium nitrate ilash nixture containing 30.8% aluminum and 69.2% otassium nitrate in a .25 caliber aluminum shell. ['his ilash mixture was lightly pressed. An iglition mixture was prepared containing 80% sad-selenium (72.4% lead, 27.6% selenium) and of the `s'al'ne aluminum-potassium nitrate lash mixture that was'employed in the base barge. Five-tenths gram of this loose ignition nixture was inserted in the shell. An electric lasting cap-type ignition assembly was inserted n such a manner that the bridge wire was emedded in the ignition mixture. The shell was ealed by a layer of waterproofing compound and y a layer of sulfur held in the shell by crimps.

These squibs were ilred in a 2.36-inch dummy 'ocket assembly as described in Example 4. They ired substantially instantaneously. In each case art oi the base charge was recovered in an uniurned condition.

Exurrx.: 7

Electric squibs were prepared using .25 caliber iluminum shells containing as the sole ilash mix- .ure 1 gram of an ignition composition comprisng 58% lead, 28.3% selenium, 18% powdered zinc, and 5% barium nitrate. These squibs )roved very superior to ordinary squibs containng diazodinitrophenol-potassium chlorate and liazodinitrophenol-potassium chlorate-charcoaliitrostarch flash mixtures. In the ignition of poyassium chlorate-trinitro-toluene explosive pelets, they gave 17 more ignitions out of 100 tests. llso, the squibs ignited C granulation black )owder in the open air at a distance 4 inches from the ignition mixture without failure in suc- :essive trials. The air cavity in delay-type ini- ',iators is usually less than 1 inch long. Thus, ahe ignition composition was shown to be sat- `sfactory in delay initiators. Twenty-live squibs ,n series showed a critical ilring current of 0.6 impere. The critical firing current for 25 squibsl with diazodinitrophenol-potassium chlorate ignition mixture in series is 0.8 ampere. These fir-v .ng currents and the ability to ignite C granulation black powder were not appreciably changed by storage of the squibs for 5 months at 50 C.

Examens Electric squibs containing 1 gram of a loose flash charge comprising 77% of a mixture of lead and selenium (72.4% lead and 27.6% selenium),

20% powdered zinc, and 3% potassium chlorate were tested for minimum tiring current and for llame-throwing ability before and after 5 months hot storage at 50 C. The shells were sealed by an asphalt waterprooilng compound and a layer of sulfur crimped in the shell. 'Ihe electric blasting cap-type ignition plugs in each case were, fitted with platinum bridge wire on 0.142 inch terminal centers. The lead wire terminals protruded 64 inch from the face oi' the plug. Aluminum, bronze, and zinc closed shells (0.267 caliber) were'employed. The minimum ring current was found to be 0.50 ampere before and after storage,

regardless of which type of shell was used.

The squibs were placed 4 inches from C granulation black powder in wire basketsand red.= No failures to ignite the powder were noted. The ilash mixture when red in aluminum or bronze shells broke open the side of the shell with not too much violence. When the mixture was iired in zinc shells, the entire bottom portion ofthe andere 8 shell Vwas usually disintegrated, thereby giving a large ilash with no indication of violence.

'I'he ignition ilash mixture in accordance with this invention contains as essential ingredients a mixture of powdered selenium and either lead or tin, a flash-producing metal such as powdered magnesium or aluminum. and a name-spreading material such as potassium nitrate or black powder. This ignition mixture may be employed in squibs, igniter fuses, blasting caps, or other electric firing devices. In electric squibs and igniter fuses it may serve as the sole ilash mixture, or, preferably, it may be used together with a mixture of a dash-producing metal, such as magnesium, and a flame-spreading material.' such as potassium nitrate or a gas-producing mixture containing an oxidizing agent such as black powder.

The ignition composition in accordance with this invention, as illustrated by the examples, contains a mixture of powdered selenium and either powdered lead or powdered tin, preferably in stoichiometrically vequivalent proportions. Such a chemically equivalent mixture contains, by weight 27.6% selenium and 72.4% lead or 40% selenium and tin. However, it has been found that mixtures containing between 64% and 80% leadl and between 20% and 36% seler nium are satisfactory. Similarly, mixtures containing' between 46% -and 69% tin and between 31% and 54% selenium have given good results. In general, ratios containing the smaller quantities of lead and the larger quantities of selenium give the smallest firing time. BetweenI about 57% and about 84% of the lead-selenium mixture by Weight of the total ignition composition is customarily employed. However, between 55% and about 90% by weight of the ignition mixture has given satisfactory results.

As the Hash-producing metal, powdered magnesium or aluminum are preferred. Of these, magnesium gives somewhat better results. Aluminum on certain occasions shows an undesirable difficulty in ignition. The 'function of the dash-producing ingredient is to ignite the smokeless powder or other explosives present.

Between about 3% and about 40% dash-producing metal, by weight of the ignition mixture, may be employed. When magnesium and aluminum are used, they should preferably comprise between 5% and 20% by weight of the ignition mixvwith the greatest economy in material.

ture. This quantity gives the optimum ash Other metals which may be employed as the flash-producing ingredient in quantities stoichiometrically equivalent to magnesium within the above ranges include zinc in an amount between 17% and 37% by weight, and, under certain circumstances, tin. Metals other than magnesium or aluminum, however, may fail to give nearly instantaneous, complete ignition of propellant rocket powder at low temperatures. Mixtures of two or more dash-producing ingredients, such as mixtures of magnesium and aluminum, may also be employed. It is desirable under certain conditions to coat the flash-producing ingredient :,with linseed oil in order to protect it from reaction With the explosives with which it may be mixed or Afrom reaction with the atmosphere.

An essential ingredient of the ignition composition is a flame-spreading material such as oxidizing compound, or a gas-producing mixture containing an oxidizing compound such as black powder, preferably in an amount suchthatthe ignition composition has a aero or slightly msitive oxygen balance. However, under-,certain circumstances a small negative oxygen balance not lower than approximately 5 may be tolerated. Higher negative oxygen balances tend to produce hangres. On the other hand, positive omen balances assist in reducing the'ignition time to a minimum. In fact. in one instance where the ignition composition had a positivev oxygen balance of 2, the ignition time was only. 0.003 second. Where potassium nitrate is the oxidizing compound, it is employed in an amount between and 30% by weight of the ignition mixture, preferably between and 25% by weight. Other 'oxidizing compounds,

euch as potassium chlorate, barium nitrate, sodium nitrate, sodium chlorate, barium peroxide, and lead' dioxide may be employed in amounts stoichiometrically equivalent to potassium ni-v trate within the ranges given above and within the limitations of oxygen balance of the composition. Preferably, potassium nitrate is used with magnesium or aluminum.

The importance of each of the essential in-l gradients in the ignition mixture may readily be demonstrated. If a mixture of lead or selenium,

esium, and potassium chlorate or nitrate 'poor flash while mixtures cont lead, selenium, and magnesium give only a` mild flash. The addition of a small' amount of a damespreading material, such as an oxidizing agent, to the mixture of lead, seleniurmand magnesium causes the ame to spit out and scatter over a wider area in a more desirable manner, and makes possible the ignition oi rocket powder substantially instantaneously at low temperatures.

The importance of e. name-spreag material in the ignition mixture is further emphasized by the results shown in Example l, comparing tests with ignition mixtures containing and lacking such an agent. However, materials which are not 'themselves oxidizing agents will give this effect. Black powder, whichY is a good reducing agent but which contains an oxidizing agent and during burning gives ou large quanhties of gas, has proved itself almost the equal of potassium nitrate in causing the-:dame to scatter in a desirable manner. It appears that any materialscontaining oxidizing compounds which liberate large quantities of gases will serve the same function. Such gas-producing materials may be employed in amounts such that the oxidizing compound is present within the ranges given for potassium nitrate, above.

The particle size of the ingredients employed must be carefully regulated in order to prevent segregation. While segregation does not necessarily produce failure, it should be avoided. The lead, tin, and selenium should be of a particle size comparable to the flash-producing metal. The llame-spreading material and the nameproducing agent should b e of approximately the same mesh size. Satisfactory particle sizes for potassium nitrate have been found to be between 30 and 150 mesh, and for magnesium about 80 mesh. Potassium nitrate which passes through rockets and the like, and. when it is employed in l blasting caps, it will ignite the priming charge. However, when employed in squibs, an even shorter ignition time has been obtained by employing in addition to the ignition mixture of this invention a ash mixture comprising a ashproducing metal and a dame-spreading material, preferably the same :dash-producing metal and the same :dame-spreading material that are employed in the ignition mixture itself. d. mixture of magnesium and potassium nitrate has given best results, and is preferred. lsiowever, mixtures of aluminum, zinc, or tin and poytassium nitrate or mixtures of flash-producing metals with other name-spreading materials may be employed. Stoichiometrically equivalent amounts of flash-producing metals and iiamespreading agents are preferable. However, between 37% and 50% magnesium and between and 63% potassium nitrate have been found operable. Stoichiometrically equivalent Quanti-- ties of hash-producing ingredients and other oxidizing agents may be substituted for magnesium. and potassium nitrate within these ranges. 4

Electric blasting caps containing the ignition mixture of this invention may contain the customary base explosives such as pentaerythritol tetranitrate, tetryl, cyclonite, mannitol hexanitrate, trnitrotoluene, nitrolactose, nitrosucrcse, etc. The blasting caps, squibs, and igniter fuse shells may be formed of copper, aluminum, lead, and other metals, cellulose acetate, ethyl cellulose, phenol-formaldehyde resin, and other plastic materials. The plugs may be formed of the standard materials including sulfur, rubber. polystyrene, phenol-formaldehyde resin, ethyl cellulose, etc. li desired, the plugs may be sealed and the 4shells made waterproof by using a sealing compound such as asphalt, sulfur, wax, or other waterproofing adhesive material. rlhe lead wires may be copper or iron wire, plain, tinned, or enameled, insulated in desirable lmanner using cotton or plastic materials. The bridge wire connecting the terminal ends of the lead wires may be electrically-resistant wire composed of noble or base metals or alloysthereoi such as platinum, Nichrome, copper-nickel, etc.

Delay electric. igniters and blasting caps have been prepared using electric blasting cap-type plugs. The loosev ignition composition may be placed in e. capsule of Celluloid or other inamrnable material, where an air space is provided, and thereby held in position about the bridge wire, or may be placed upon the delay fuse, where an air space is not needed. The ,ignition mixture has satisfactorily ignited delay fuses having cores of black powder, barium peroxide-selenium,-

and other standard del-ay powders.

The improved squibs in accordance with this invention have been found particularly useful for insuring the ignition of smokeless powder of the type used in rockets in an extremely low ignition time. They may be usedin rockets of all sizes.

When used in l5-'inch or larger rockets, it may jC. to 54 C. and above.

y of the ignition composition; and an amount of --30% potassium nitrate based position.

il be advisable to insert the squib in a bayonet igniter-a long narrow tube iilled-with a ilash mixture, such as black powder. The squib ignites the ilash mixture, which then provides a greater scattering eiiect the full length of the rocket motor.'

These squibs show an improved rapid ignition time at low and high temperatures, from 40 They have shown substantial reductions in critical ring current when fired in series.

This application is a continuation-in-part of my application for U. S. Letters Patent, Serial No. 449,695, now Patent No, 2,370,159, iiled July 3, 1942.

What I claim and desire to protect by Letters Patent is:

1. An ignition compositionv comprising seleniumand a material of the group consisting of lead and tin in-which the selenium to lead proportion is 20-36% selenium to 64-80% lead and the selenium to tin proportion is 3154% selenium to 4669% tin by weight; from 340% of a llame-producing material based on the weight a flame-spreading material comprising an oxygen-yielding salt stoichiometrically'equivalent to on the weight of the ignition composition.

2. An ignition composition comprising selenium and a material of the group consisting of lead and'tin in which the selenium to lead proportion is 2036% selenium to 64-80% lead and the selenium to tin proportion is 3154% seleniumcto 4669% tin by weight;. from3-40% of magnesium based on the weightof the ignition composition; and an amount of a flame-spreading material comprising an Oxygen-yielding salt stoichiometrically equivalent to 5-30% potassium nitrate based on the weight of the ignition com- 3. An ignition composition comprising selenium and a material of the group consisting of lead and tin in which the selenium to lead proportion is 20-36% selenium to 64-80% lead and the Se'- lenium to tin proportion is 3154% selenium to 46-69% tin by weight; .from 3-40% of zinc based on the weight of the ignition composition; and an .amount of a flame-spreading material comprising an oxygen-yielding salt stoichiometri cally equivalent to 530% potassium nitrate based on the weight'of the ignition composition.

4. An ignition composition comprising selenium and a material of the group consisting of lead and tin in which the selenium to lead proportion is 2036% the selenium to tinproportion is 3154% selenium to 46-69%-tin by weightyfrom 340% oi! aluminum based on the weight of the ignition composition; and an amount of a flame-spreading material comprising an oxygen-yielding salt stoichiometrically equivalent to 5-30%I potassium nitrate based on the weight of the ignition composition.

5. An ignition composition comprising sele.- nium and a material of the group consisting of lead and -tin inwhich the selenium to lead proportion is 2036% selenium to (i4-80%' lead and the selenium to tin proportion is 31-54% selenium to .4G-69% tin by weight; from 3-40% of magnesium based on the weight of the ignition composition; and 5-30% of potassium nitrate based on the Weight of the ignition composition.

6. An ignition composition comprising selenium and a material of the group consisting of selenium to 6480% lead and 5 ignition composition.

12 lead yand tin in which the'selenium to lead proportion is 20-36% selenium to 6480% lead and the selenium to tin proportion is 31-54%vsele nium to 46-69% tin by weight; vfrom 3-40% oi' zinc based on the weight oi the ignition composition; and an amount of potassium chlorate Y which is stoichiometrically equivalent to 5-30% of potassium nitrate based on the weight of th 7. An ignition composition comprising selenium and a material of the group consisting oi lead and tin in which the selenium to lead proportion is 2li-36% selenium to 64-80% lead and the selenium to tin proportion is 31-54% selenium to lift-69% tin by weight;vfrom 340% of vzinc based on the weight of the ignition composition; and an amount nf barium nitrate which is stoichiometrlcally equivalent to 5-30% of potassium nitrate based on the weight oi' the ignition composition.

8. An ignition composition comprising selenium and a material of the group consisting of lead and tin in which the selenium to lead proportion is 20-36% selenium to 64-80% lead and the selenium to tin proportion is 31-54% selenium to 4669% tin by weight; from 340% o! aluminum based on the weight ofthe ignition composition; and between 5-30% of potassium nitrate based on the weight of the ignition composition.

9.V An electric initiating ndevice comprising 'a shell, a ring assembly and a llame-producing mixture comprising an ignition composition consisting of selenium and a material of the group consisting of, lead and tin in which the selenium to lead proportion is 2li-36% selenium to 6480% lead andthe selenium to tin proportion is 31-54% selenium to 46-69% tin by weight, from 3-40% of a name-producing metal; and an amount of a flame-spreading material comprising an oxygenyielding salt stolchiometrically equivalent to 530% potassium nitrate based on the weight oi.'

spreading material comprising an oxygen-yielding salt stoichiometrically equivalent to 530.% potassium nitrate based on the weight oi the ignition composition.

11. An electric initiating device comprising a shell, a flring assembly and an ignition composition comprising selenium and a material of the group consisting of lead and tin in which the selenium to lead proportion is 2li-36% selenium to 64-80% lead and the seleniumfto tin proportion is 31-54% selenium to 46-69% tin by weight; from 340% of zinc based on the weight of the ignition composition; and an amount of a flamespreading material comprising an oxygen-yielding salt stoichiometrlcally equivalent to 530% potassium nitrate based on .the weight of theignition composition. i

l2. An electric initiating device comprising a shell, a firing assembly and an ignition composlyielding salt stoichiometrically 'equivalent to 5 5-30% potassium nitrate based on the weight of the ignition composition.

EDWARD J. HANLEY.

REFERENCES CITED The following references are of record in the le of this patent:

Number -14 UNITED STATES PA Name A Date Dahmen Sept. 29, 1903 Cahuc Nov. 2, 1909 Large Sept. 26, 1933 Placard Aug. 28, 1934 Alexander Feb. 5,4 1935 Burrows July12, 1938 Burrows et al Jan. 14, 1941 Lawrence May 30, 1944 Hanley Feb. 27, 1945

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