GRASS AND HAY 215 



origin of this fire may be lacking, the circumstances are such that it 

 seems safe to consider it of spontaneous origin. 



It is well known that when moist hay is stored under favorable 

 conditions fermentation takes place, which may produce a consider- 

 able amount of heat. According to recent investigations made in 

 Germany, the amount of heat may be sufficient to set fire to the hay. 

 Under suitable conditions some of the organic matter of the hay is 

 oxidized by the oxygen of the air. Carbon dioxid and water are 

 produced. The water moistens the hay and the moistened material 

 ferments. Fermentation produces carbon dioxid, water, and small 

 amounts of other compounds. Heat also is produced. The fermen- 

 tation is more active if the material is moistened at the beginning. 

 However, the water produced by the oxidation of the materials is 

 sufficient to start it. This fermentation produces a temperature of 

 about 132.8 F. At this temperature a second and more violent 

 oxidation takes place and the temperature rises to about 194 F. 

 Other processes then take place which char the material and cause a 

 slow rise of temperature to 266 F. When this temperature is 

 reached, the hay chars rapidly. All these processes destroy at least 

 half of the material present. Theoretically, the temperature may 

 rise to 374 F. According to the tests made, clover hay will become 

 ignited at 302-392F. 



Spontaneous combustion is indicated by the hay becoming 

 darker in color until it is finally black, by a sooty odor, and by 

 smoke irritating to the eyes. The ash of the burned hay has a char- 

 acteristic grayish-white appearance and feels like sand. The burned 

 hay is surrounded by a layer of charred but not burned material, 

 which is a poor conductor of heat. 



(Authorities Consulted on Grasses. U. S. Dept. Agr. Botanical 

 Div. Special Bulletin; do. Div. Agros. B. 14 and B. 15; N. J. Agr. 

 Ex. Sta. B. 207; Tex. A. E. S. B. 103; Mass. A. E. S. B. 134; Tenn. 

 B. 1, Vol. IV; N. H. A. E. S. B. 129; S. Dak. A. E. S. B. 66; Mont. 

 A. E. S. B. 36; Neb. A. E. S. B. 84; Tenn. Parts I. and II. Bui. 

 1892-94; Iowa A. E. S. B. 54; B. 5"6; Tex. A. E. S. B. 59; Vt. B. 

 149; R. I. B. 103; Iowa B. 83; N. J. B. 190; R. I. B. 82; Minn. B. 

 20; Ariz. Timely Hints Cir.; Ind. B. 29; Kans. B. 86; Va. B. 180; 

 La. Ann'l Rpt. 1901; Wyo. B. 46; Colo. B. 61; Ky. B. 124; Okl. B. 

 70; N. Dak. B. 47; Kans. B. 141; Nev. B. 33; Okl. B, 55; Tenn. B. 

 4, Vol. IL; Mich. B. 20; Ore, B. 19; Kans, B. 87,) 



