228 EVERY MAN HIS OWN FARRIER 



to RumfortPs plan. But heating liquids by steam 

 is • not so easy a process as would seem at the 

 lirst thought. There must be a large [that is large in 

 proportion to the quantity of liquid to be warmed] and 

 strong boiler, with two safety valves, one opening out- 

 wards to let out the steam, if by the sudden increase of 

 heat it should acquire so much elasticity as to endanger 

 the bursting of the boiler ; and one valve opening in- 

 wards to prevent the sides of the boiler from being 

 collapsed, or crushed inward, or the liquid from being 

 forced out of the cistern through the steam tube into 

 the boiler by the weight of the atmosphere. Then 

 there must be steam tubes rising- some height above the 

 surface of the wash in the cistern, and descending, 

 vertically, to near its bottom. The steam must be so 

 elastic as to overcome not only the pressure of the 

 atmosphere, b#t also the additional pressure of that 

 part of the liquid in the vessel, containing the wash, 

 which lies above the opening or end of the tube where 

 the steam is discharged into the vessel. 



Various means may be used to give the wash a tem- 

 perature conducive to fermentation. Water-tight tubes 

 filled with hot air, from a furnace or a stove, might 

 answer the purpose by being carried through the cis- 

 tern containing the wash to be fermented. But for 

 common farming purpose, we believe it will be best 

 either to keep up a moderate degree of heat in the room 

 or cellar in which the wash is kept for fermentation, 

 by means of stoves, or to make use of kettles or cal- 

 drons set in brick in the common way, in which, after 

 the materials have been well boiled, the liquid must be 

 kept of a proper temperature for fermentation, by oc- 

 casionally heating them. Wooden vessels, or circular 

 rims of wood, may be so adapted to the tops or rims 

 of these kettles, that the whole will contain three or 



