320 APPLIED SCIENCE 



in them is a non-conductor of heat, and, therefore, when the 

 surface of the tubes is covered with soot only a portion of the 

 heat of the gases passing through them can get to the v/ater 

 surrounding the tubes. The remainder is carried to the 

 chimney. In a boiler tube, a layer of soot J/g in. thick will 

 cause as much waste of fuel as A in. of scale. When burning 

 bituminous coal, soot will collect to the above depth in about 

 ten hours. Therefore, in order to have reasonably clean tubes 

 at all times it is necessary to clean them once each day. 



361. Care of Boiler. The boiler should be inspected 

 frequently during construction, and when completed should 

 be thoroughly tested. After the boiler is in position and the 

 brickwork completed, it should be allowed to stand, if possible, 

 for a week in order to give the brickwork a chance to dry and 

 set. After this it may be filled to the proper level and a small 

 fire kept burning under it for a few days. Great care should 

 be taken at this time not to heat up the boiler and brickwork 

 too quickly. 



In starting up a new boiler, it is a good plan to put a few 

 pounds of sal soda in the water, and then, after the brick- 

 work is well dried and set, to let down the fire and steam, run 

 off the water, and give the boiler a good washing out. This 

 treatment will be found to prevent the foaming which so often 

 occurs when a new boiler is started. This foaming is caused 

 by the grease left in the boiler by the boiler-makers. 



The fireman who has charge should at all times, before 

 starting his fire, see that the water in the boiler is at the 

 proper level. He should not be satisfied by merely looking 

 at the water glass, but should open the cock at the bottom of 

 the glass, and also try the gauge cock. Many accidents have 

 occurred through neglect of this duty. He should also see 



