Vol.. XVIII. No. 462. 



THE AGRICULTURAL NEWS. 



269 



SPONTANEOUS COMBUSTION. 



So-called ' spontaneous combustion ' in reterence to such 

 things in ships' cargoes, as coal, cotton, hay, tobacco, and cacao 

 is a subject of considerable importance in the tropics. The 

 Journal of the Royal Society of Arts for June 20 contains a 

 paper on the subject, read by Mr. Watson Smith, F I.C, 

 before the .Society. This paper begins by explaining that 

 spontaneous combustion arises by reason of such chemical and 

 physical changes in bodies, mostly consisting of or containing 

 carbon, and under the influence of atmospheric oxygen, that 

 sufficient heat is generated to give rise ultimately to 

 combustion. In a general way the most freqiieot places 

 «f spontaneous combustion occur in coals and not many years 

 ago the German Government, after an elaborate inquiry, 

 declared ttiat more ships were lost through such outbreaks 

 than through any other cause. It is noted that coal, con- 

 taining throughout its mass pyrites, is most inclined to fire 

 when in a damp state. This should cause certain precautions, 

 such as observations of temperature at certain periods to 

 be regularly taken. 



Another substance in which fires may arise through the 

 gradual generation of heat, is qnick lime. It is well 

 known that if water be suddenly added to quick lime 

 there is a rapid generation of heat, and this m y be quite 

 enough to set fire to dry material or inflammable substances 

 in closB proxiiiiity. Owing to its physical properties 

 charcoal is liable to fire. It has been found by experi- 

 ments that finely ground charcoal placed in a barrel attained 

 a temperature of 75° C. after fifteen hours ; after 

 twenty hours ignition took place. This was due to the 

 absorption of oxygen and a certain quantity of water. This 

 circumstance might be borne in mind in connexion with 

 the transmission of seed like cacao or rubber in damp 

 charcoal from one part of the tropics to another. If trans- 

 mitted in large quantities it should be quite possible for 

 enough heat to be produced to kill the seeds, if not to set 

 fire to the parcel. 



The statement that wet cotton is liable to break out in 

 combustion is improbable; but a spark getting into a bale will 

 smoulder for a long time, and the fire eventually occurring will 

 then be probably stated as having been due to .spontaneous 

 combustion. Greasy cotton is undoubtedly dangerous, most 

 fatty oils absorbing oxygen rapidly with the generation of 

 much heat. A case is recorded in which a firm received a 

 consignment of Indian cotton damaged with river water, and 

 it was offered for sale by auction. On the auction day, the 

 eooper observed that a number of bales had burst several of 

 their encircling iron bands, and the heating of the cotton was 

 .perceptible. Investigation showed that these bales contained 

 an extraordinary proportion of cotton seeds. The germination 

 of the seeds in the bales could not proceed, but the heat 

 produced was enough to cause expansion of the air, and 

 to raise the tempsrature very nearly high enough to set fire 

 to the cotton. 



In the case of tobacco, fermentation is frequently the 

 cause of combustion. Also in the case of ensilage there is 

 some danger of over-heating. Care should be taken in 

 West Indian islands where silos have been erected to institute 

 a proper routine for cliecking the temperature from time to 

 time. In regard to such substar.ces as dried fish, g-ian", 

 and bone dust, it is recorded that on one occasion a few 

 hundred tons of such material were landed from a ship at 

 Glasgow, and at once placed in bulk in a store on a stone 

 floor. In a short time the material began to heat internally, 

 and so it was opened out and spread more thinly over the 

 floor by a gang of men, this of course bringing the heated 

 Btatt more in contact with the ')xygen of the air. While 



this spreading out waM taking place a large quantity of tho 

 material took fire, and before extinction could be efl'ected a 

 portion of the enclosure was destroyed. 



Amongst the acids the most dangerous are sulphuric acid 

 and nitric acid. Asships' freights, thecarbiys in straw should 

 be stored with great care, and enclosed either under deck or • 

 on deck with sand so that should the safety of the ship 

 demand it, they can be readily thrown over the side. 



KOSTER'S CURSE. 



An interesting memorandum by .Mr. Jepson, Government 

 Entomologist, Fiji, has been received by this department 

 through the Colonial Ottice The memorandum consists of 

 remarks and observations on the spread of a noiious weed in 

 Fiji called Roster's Curse and known botanically as CUdemia 

 hirta. This weed occurs commonly in British Guiana 

 and in most of the West Indian islands, but it is 

 not a weed that causes, in the West Indies, a serious 

 amount of trouble. A note on the subject appeared in the 

 Agricultural Ndvs, Miy 3, 1919. In Fiji, however, it is 

 of a most troublesome character, and what makes matters 

 worse is r.ipidly spreading into zones which were formerly 

 free from its presence. A gentleman known as Mr. Corbett is 

 referred to in the memorandum as the originator of certain 

 suggestions as to why the weed is such a pest in Fiji and as 

 to measures that might be taken to control the weed. Most 

 of these suggestions Mr. Jeps m shows to be impracticable. 

 One point however appears to be definite, and that is 

 the statement that the weed in Fiji is principally 

 distributed by birds known as mynahs. Mr. .Jepson 

 considers that the absence of Indian mynahs in the 

 West Indian Colonies is the true explanation of the 

 dormant condition of this plant in those places. It is 

 certain that in the West Indies the weed is not controlled 

 by insect or fungus enemies. Mr. Jepson has recently made 

 an examination of the stomach content of some mynahs shot 

 at Nasinu, with the following remarkable resjlt. Up to the 

 time of writing six birds had been examined, and seeds of 

 Clidemia, hirta were found in every instance. In all, 

 14,084, were isolated, or an average nf 2, .347 feeds per bird. 

 The greatest number of seeds found in one bird was 6,644. 

 There is no doubt therefore from this and other evidence in 

 the possession of the Fiji Department of Agriculture, that 

 mynahs feed freely upon the ripe berries of Clidcmia liirta 

 and that they are active disseminating agents of the weed 

 in the colony. 



Mr. Jepson considers it desirable to draw the attention 

 of other Colonial Governmeats to the above habits of this 

 bird. Its introduction some thirty years ago into Fiji was 

 done with the object to benefit planters, owing to its sup- 

 posed insectivorous hibits. Mr. Jepson considers that the 

 introduction of this bird to other colonies would be danger- 

 ous The luynah has the reputation of being useful as a tick 

 destroyer on cattle. Careful observation shows, however, 

 that although th^s bird does settla on the backs of cattle, it 

 is more with the object of catching grasshoppers disturbed 

 by the animal as it grazes than with the object of consuming 

 ticks which, after all. arc most commonly found in the 

 inaccessible places of the animal's body. 



The suggestion was imde sometime ago by a convention 

 of planters in Fiji, that a scientific oflicer should be sent to 

 the West Indies to disjover why Clidemia hirta is not a 

 noxious weed in those colonies. On the basis of the state- 

 ments given alove it his been decided that such a course is 

 now quite unnecessary. 



