282 Heating hy the Circulation (rf Fluids. 



83 



The arguments that may be adduced in favour of this 

 scheme are, that, wherever there is a large range of hot- 

 houses, lime is continually wanting for manure, and that thus 

 the lime burnt would be no drug, and the heat disengaged in 

 slacking it might be economically thus employed : that, in 

 the burning of lime, part of the carbonic acid which is dis- 

 engased is converted into carbonic oxide, and thus becomes 

 inflammable, and burns ; so that the lime itself, in this case, 

 becomes a valuable fuel : that, this being the case, the lime 

 would be burnt with little or no expense ; and, instead of the 

 heating of a large range of houses costing a large annual 

 sum, would produce a saving, by yielding a valuable result. 

 The sole argument against it is complication of apparatus : 

 however, experience would soon simplify that greatly. 



There are many useful applications of the circulation of 

 hot water yet to be thought of, and many thought of that 

 have not yet been applied. Why might not the feet of 

 outside passengers on night coaches be kept warm by the 

 waste heat of the lanterns ? to take one instance out of 

 many. 



Should you approve of it [we do most cordially], I will, at a 

 future time, send you some further thoughts on hot water, &c. 



I am, Sir, yours, &c. 

 94". CaiJcl Street^ Dublin, Robert Mallet. 



April 18. 1833. 



