was first used in Pittsburg, it has already displaced about 40,000 bushels of coal per day in these mills.  Sixty odd glass works, which required about 20,000 bushels of coal per day, mostly now use the natural gas.  In the work around Pittsburg beyond the city limits, the amount of coal superseded by gas is about equal to that displaced in the city.  The estimated number of men whose labor will be dispensed with in Pittsburg when gas is generally used is 5,000.  It is only a question of a few months when all the manufacturing carried on in the district will be operated with the new fuel.  As will be seen from the analyses appended to this paper, it is a much purer fuel than coal; and this is a quality which has proved of great advantage in the manufacture of steel, glass, and several other products.  With the exception of one, and perhaps two concerns, no effort has been made to economize in the use of the new fuel.  In our Union Iron Mills we have attached to each puddling furnace a small regenerative appliance, by the aid of which we save a large percentage of fuel.  The gas companies will no doubt soon require manufacturers to adopt some such appliance.  At present, owing to the fact that there is a large surplus constantly going to waste, they allow the gas to be used to any extent desired.  Contracts are now made to supply houses with gas for all purposes at a cost equal to that of the coal bill for the preceding year.  In the residences of several of our partners no fuel other than this gas is now used, and everybody who has applied it to domestic purposes is delighted with the change from the smoky and dirty bituminous coal.  Some, indeed, go so far as to say that if the gas were three times as costly as the old fuel, they could not be induced to go back to the latter.  It is therefore quite within the region of probability that the city, now so black that even Sheffield must be considered clean in comparison, may be so revolutionized as to be the cleanest manufacturing center in the world.  A walk through our rolling mills would surprise the members of the Institute.  In the steel rail mills for instance, where before would have been seen thirty stokers stripped to the waist, firing boilers which require a supply of about 400 tons of coal in twenty-four hours—­ninety firemen in all being employed, each working eight hours—­they would now find one man walking around the boiler house, simply watching the water gauges, etc.  Not a particle of smoke would be seen.  In the iron mills the puddlers have whitewashed the coal bunkers belonging to their furnaces.  I need not here say how much pleasure it will afford me to arrange that any fellow members of the Institute who may visit the republic are afforded an opportunity to see for themselves this latest and most interesting development of the fuel question.  Good Mother Earth supplies us with all the fuel we can use and more, and only asks us to lead it under our boilers and into our heating and puddling furnaces, and apply