A Disastrous fire at Demossville last night totally destroyed the dwelling, store-house and tobacco warehouse of Mr. J. M. Stephens, and also the residence of Dr. McGill.  The buildings were of frame and the warehouse contained a quantity of tobacco.  The loss can not fall short of about $10,000 or $15,000 for Stephens, $700 of which is covered by insurance in the Aetna.  Dr. McGill's residence was uninsured.  The fire was evidently the work of an incendiary, as a lot of cotton saturated with turpentine was discovered piled against the warehouse where the flames first broke out.