3,274,035 United States Patent Office Patented Sept. 20, 1966

2 Example I 3,274,035 METALEC COMPOSTON FOR PRODUCTION OF Ingredients: Percent by weight HYGROSCOPEC SMOKE Lithium carbonate ------19.34 Lohr A. Barkardt and William G. Finnegan, China Lake, ------20.66 Calif., assignors to the United States of America as Aluminum ------20.50 represented by the Secretary of the Navy Potassium ------39.50 No Drawing. Fied June 5, 1964, Ser. No. 375,402 This composition burns completely and leaves no resi 4 (Caims. (C. 49-40) due, i.e., all the reaction products are volatilized. The The invention herein described may be manufactured 0. percentages of lithium carbonate and hexachloroethane and used by or for the Government of the United States may vary from the values stated so long as their mutual of America for governmental purposes without the pay proportions remain the same. ment of any royalties thereon or therefor. The ingredients are blended and compression molded This invention relates to new compositions for pyro into appropriate containers. technic production of hygroscopic Smokes. Example II Many compositions and methods are known to the art for producing smokes for concealment purposes as well Ingredients: Percent by weight as cloud seeding. A variety of haloid compositions have Lithium carbonate ------16.9 been made which are said to produce hygroscopic Smoke. Hexachloroethane ------18.1 They consist essentially of an admixture of an oxidant, 20 Aluminum ------22.3 a fuel, a halogen donor and a halogen receptor. Other Potassium perchlorate ------42.7 substances, which dispersed, have cloud nucleating char The above composition was mixed and pressed into acteristics include the well-known iodides, silver, lead, a cylinder one-inch diameter, one-half inch long with a and copper, cupro-oxide, copper sulphide, copper selenide, one-fourth inch hole. This cylinder was ignited using mercury telluride, vanadium pentoxide, silver Sulphide, 25 a loose packed mixture of 2.42% lithium carbonate, silver nitrate, silver oxide and cadmium telluride. The 2.58% hexachloroethane, 32.5% aluminum and 62.50% pyrotechnic generation of zinc, aluminum and magne potassium perchlorate in the hole as an igniter. The sium chlorides by the reaction of these in pow composition burned, leaving no residue and producing dered form with tetrachloride and hexachloro a white Smoke cloud. The solid matter in the cloud was ethane with other additives for the production of Smokes 30 Sampled using a cold plate and the solid products for concealment purposes is well-known. These mate Were identified as aluminum oxide (Al2O3), potassium rials have fairly low hygroscopicities. Since dispersion chloride (KCl) and lithium chloride (LiCl). The solid of many of the above-mentioned cloud nucleating mate product was quite hygroscopic and absorbed water from rials is accomplished by use of concentrated solutions the atmosphere, although the relative humidity at the in spray-type devices, the total effectiveness is reduced. 35 time was probably below 5%. The present invention provides compositions which show The decomposition of this new composition may be as good capability of forming nuclei for cloud seeding represented by the following unbalanced equation: as any of the compositions used heretofore, and is sim A ple and easy to obtain. LiCO3 + C2Cls -- Al -- KClO --> It is therefore an object of this invention to provide 40 LiCl -- KCl -- Al2O3 -- CO2 -- CO a composition which produces hygroscopic smoke for Obviously many modifications and variations of the use in influencing the weather. present invention are possible in the light of the above Another object is to provide a material which can be teachings. It is therefore to be understood that within used for clearance of fog from large areas such as air the scope of the appended claims the invention may be craft runways. 45 practiced otherwise than as specifically described. Yet another object is to produce a hygroscopic smoke What is claimed is: for inducing precipitation from warm clouds. 1. The composition which produces hygroscopic smoke Other objects, features and many of the attendant ad comprising an admixture of the following ingredients: vantages of this invention will become readily appreciated Ingredients: Percent by weight as the same become better understood by reference to 50 the following detailed description: Lithium carbonate ------19.34. The present invention is for a composition which upon Hexachloroethane ------20,66 combustion yields hygroscopic smoke. It comprises a Aluminum ------20.50 carbonate selected from the group consisting of lithium, Potassium perchlorate ------39.50 sodium, potassium, cesium, rubidium, , magne 55 2. The composition which produces hygroscopic smoke sium, and carbonates and mixtures comprising an admixture of the following ingredients: thereof; a light metal selected from the group consist Aluminum ing of aluminum, magnesium, zinc and zirconium and Potassium perchlorate mixtures thereof; and an inorganic oxidizer selected from Lithium carbonate the group consisting of nitrates and of so 60 Hexachloroethane; dium, lithium, potassium, calcium, barium and strontium; the percentage of said ingredients being such that and a polyhalogen compound selected from the group upon combustion of said composition a stoichi consisting of hexachloroethane and octachloropropane. ometric reaction occurs. The percentages used must be such that stoichiometric 3. A composition which produces hygroscopic smoke reactions occur and complete volatilization of the com 65 comprising the following components: bustion products is obtained. Components Parts by weight The following examples better illustrate this invention Pyrotechnic mixture ------1.5 but should not be considered as limiting. Smoke generating mixture ------1.

m 3,274,035 3 4. said pyrotechnic mixture consisting essentially of alu- References Cited by the Examiner minum and potassium perchlorate; and UNITED STATES PATENTS said smoke generating mixture consisting essentially of lithium carbonate and hexachloroethane. 2,939,780 5/1960 Brock ------149-40 4. A composition which produces hygroscopic smoke 5 2,995,526 8/1961 De Ment ------149-40 X comprising the following ingredients: a carbonate selected from the group consisting of so- OTHER REFERENCES dium, potassium, cesium, rubidium, calcium, magne- Bebie: Manual of Explosives, Military Pyrotechnics sium, strontium and barium carbonates and mixtures and Chemical Warfare Agents, Macmillan Co., New York, a lightthereof; metal selected from the group consisting- of mag l0 N.Y., page 79. nesium, zinc, aluminum and zirconium and mixtures References Cited by the Applicant thereof; UNITED STATES PATENTS an inorganic oxidizer selected from the group consist ing of sodium perchlorate, lithium perchlorate, po- 15 2,756,097 7/1954 Brandau et al. tassium perchlorate, calcium perchlorate, barium 2,775,515 12/1956 Magram. perchlorate, strontium perchlorate and the corre- 2,895,679 7/1959 Elton. sponding nitrates, and mixtures thereof; 2,934,275 4/1960 Ball. a polyhalogen compound selected from the group con- 2,993,648 7/1961 Blackwell. sisting of hexachloroethane and octachloropropane; 20 the percentages of said ingredients being such that upon 3,056,556 10/1962 Sanger et al. combustionaction occurs. of the composition a stoichiometric re- BENJAMIN R. PADGETT, Primary11 Ms. Examiner.Fr. 1 r.