ON SPONTANEOUS INFLAMMATIONS* ^41 



i"efidue of the combuftion, efpecially if the combiiftible is not 

 entirely confumed, and a part is not reduced into charcoal, 

 which frequently happens in the fire-places in which the com- 

 buftibles are not burned in grates, and the afhes are not fepa- 

 rated from the charcoal. There have been inflances of houfes 

 having been burnt by aflies intermingled with the charcoal 

 which had been taken too early from the fire-place and put 

 into places where they were furrounded with combuftibles, 

 •which they fet on fire by a fpontaneous inflammation. Hap- 

 pily thefecaufes of conflagration rarely occur; for pyrophorus 

 does not retain its property of inflaming for any length of lime, 

 and it is frequently decompofed fliortly after its produdlion, 

 without occafioning any unpleafant event : neverthelefs, care 

 fiiould always be taken not to put aflies newly burned, and 

 which are ftill intermingled with charcoal, in places where 

 they can communicate with combuftibles. 



The formation of a pyrophoricmatter is principally obferved 

 in the preparation of the ibda of commerce, which is obtained 

 by the incineration of different maritime plants containing 

 much fulphate of foda, and which, in the combuftion, fome- 

 limes furnifli a certain quantity of fulphur, greater or lefs, ac- 

 cording to the manner in vv-hich the operation is direfted. 



The formation of phofphuret of lime has great analogy with 

 that of fulphuret of lime. Although the phofphoric acid is not 

 found fo often in vegetables as the fulphuric acid, it neverthe- 

 lefs exifts in them in greater quantity than has hitherto been Phofphoric acid 

 believed : it is principally found in moft plants which grow in '^ ^ ^^1^"^ ^"^ 

 marfliy places, in turf, and in feveral fpecies of the white 

 woods. In reducing thefe woods into charcoal, a fmall quan- 

 tity of phofphorus is fometimes formed, which may remain 

 combined with the fame bafes as retained the phofphoric acid 

 before the combuftion : the phofphorus, by forming other 

 comb..iations, may be rendered incapable of occafioning any 

 accident, but it may alfo happen from a concurrence of feve- 

 ral circumflances-, lliat charcoal impregnated with any phof- 

 phuret whatever, may, by expofure to the a6lion of a warm 

 and humid air, difengage phofphorated hidrogen gas, whicii, 

 by the contact of the atmofpheric air, will take fire and com- 

 municate the inflammation to the mafs of the charcoal. 



Two examples of this kind of fpontaneous combuflion have Spontaneous In- 

 taken place in the powder magazine of Eifone, in the years 8 cn^^',5'i'n a * 



Vol. VIIL— August, 1804. K and p wder maga» 



