144 Of the Management of Fire 



the boilers of steam engines, for distilleries, and for 

 various other purposes. As the escape of heat into 

 the brick-work is almost entirely prevented, and as the 

 surface of the boiler on which the heat is made to act 

 is greatly increased by means of the hollow walls, the 

 liquid in the boiler is heated in a very short time, and 

 with a small quantity of fuel. 



There is still another advantage attending this con- 

 struction, which renders it highly deserving the attention 

 of distillers. By making the tops of the flues arched 

 instead of flat (which may easily be done, and which is 

 actually done in the boiler in question), or in the form 

 of the roof of a house, as the hottest part of the flame 

 will, of course, always occupy the upper part of the flues, 

 and as the thick or viscous part of the liquor in the 

 boiler that which is in most danger of being burned 

 to the bottom of the boiler, and giving a bad taste to the 

 spirit which comes over cannot well lie on the convex 

 or sloping surface of these flues, there will be less danger 

 of an accident which distillers have hitherto found it 

 extremely difficult to prevent. 



In constructing boilers on these principles for distil- 

 lers, it will probably be found necessary to increase very 

 much the thickness of the hollow walls of the flues, 

 and perhaps to make them even deeper than the level 

 of the bottom of the flues, in order more effectually to 

 prevent the thick matter which will naturally settle in 

 those cavities from being exposed to too great a heat. 



A similar advantage will attend large boilers con- 

 structed on these principles for making thick soups for 

 hospitals ; these soups being very apt to burn to the 

 bottoms of the boilers in which they are prepared. 



I made another experiment in the House of Industry 



