A Staunton, Va., correspondent sends a sketch of a bath boiler, here reproduced, explaining that in that section of the country they have a very strong limestone water. What he wants to know is whether with this form of arrangement the stopping up of the water-back with lime will be prevented; also, whether the water in the boiler can be heated in as short a time as in the ordinary form of boiler; and, finally, whether the water in passing through A B will not find its way into the pipe C.

The principle of the boiler is the same as that utilized in many forms of water heaters now on the market, the pipes within the heaters, however, serving for the circulation of waste steam instead of hot water, as in the present case. These heaters, as our correspondent undoubtedly knows, all work more or less successfully. In the particular case under consideration the water-heating capacity, or the rapidity with which the water in the boiler D will be heated by the circulation of hot water in the pipes A B, is simply a question of heating surface in the pipes A B and in that part forming the water-back. With sufficient surface, relatively, to the amount of water in the boiler D, we do not see why good results should not be reached. The tendency of hot water from the pipes A B to enter the pipe C is slight; not worth considering, in fact, unless the connection were of so very large a diameter as to admit of circulation within the pipe itself. The chance of this is remote. Some heat will go to the cold water in the inlet pipe by conduction, but this will be slight.

The theory in this case of the prevention of lime obstruction in the water-back obviously is that the water which is once admitted to the pipe system A B and the water-back extension practically remains there, unchanged in quality, except so far as that change is concerned which occurs after it is heated for the first time by circulation through the water-back. This first heating would have the effect of causing a separation of some of the scale-forming impurities held in solution, after which there would be no tendency to form a further deposit. The pipes A B and water-back would probably not be stopped up by this comparatively small amount of initial scaling, though in the course of time, if the water contained in them be drawn off occasionally and fresh water let in from the cold-water supply pipe, new deposits would be formed, which would ultimately, if this drawing off and refilling be repeated often enough, clog the pipes.

Hot-Water Coil For Boiler

The scale-forming matter in the water which is heated in the boiler D by the pipes A B would be deposited in the boiler itself, and not interfere with the working of the water-back.