=An American Slave in England.= Douglas, who escaped from slavery and found his way to England, has received marked attention from the nobility and gentry of England. He has attended their soirees, occupied the most honorable positions at their dinner parties, rode in their carriages, flirted with their daughters, walked arm in arm through their gardens with lords, viscounts, counts and mayors of cities. * * * * * Many of the girls employed in the mills of the Nashua Corporation, have refused to work by candlelight. They may be right. THE =SCIENTIFIC AMERICAN=. Persons wishing to subscribe for this paper, have only to enclose the amount in a letter directed (post paid) to MUNN & COMPANY, Publishers of the Scientific American, New York City. TERMS.--$2 a year; ONE DOLLAR IN ADVANCE--the remainder in 6 months. _Postmasters_ are respectfully requested to receive subscriptions for this paper, to whom a discount of 25 per cent will be allowed. Any person sending us 4 subscribers for 6 months, shall receive a copy of the paper for the same length of time. Observations on the more recent Researches concerning the operations of the Blast Furnace in the Manufacture of Iron. BY DR. J. L. SMITH. The great difference existing between metallurgical operations of the present day, and those of a former period, is owing chiefly to the ameliorations produced by the application of the science of chemistry to the _modus operandi_ of the various changes taking place during the operations, from their commencement to their termination. Copper and some other metals are now made to assume forms in the chemist's laboratory, that formerly required great artistical skill for their production--the chemist simply making use of such agents and forces as are at his command, and over which he has, by close analytical study, acquired perfect control. Our object, at present, is only to advert to the chemical investigations more recently made on the manufacture of iron, treating of those changes that occur in the ore, coal and flux, that are thrown in at the mouth of the furnace, and in the air thrown in from below. For most that will be said on this subject, we are principally indebted to the recent interesting researches of M. Ebelman. The importance of a knowledge of the facts to be brought forward, in this article, will be apparent to every one in any way acquainted with the manufacture of iron. It will be seen that the time is not far distant when the economy in the article of fuel will amount in value to the present profit of many of the works. The consequences must be, that many of those works that are abandoned will be resumed, and others erected in localities formerly thought unfit.