Hints for Experiments. 



365 



128 



Art. VII. Hints for Experiments. 



Heating Pits and Frames by Gordon's Kettle. — In Gordon's kettle 

 {Jig. 128.), which is heated by a lamp, or by a jet of gas, the heat accu- 

 mulates between the outer coat and the inner 

 vessel, which contains the water, and by this 

 means boils the water in half the time re- 

 quired by a common kettle. Might not steam 

 be generated in this way at an easy rate, and 

 made to heat a cistern of water, even though 

 at some distance from it ; or, might not a 

 system of circulating hot water in a hot-bed 

 or pit be contrived with a Gordon kettle and 

 a set of tin pipes ? Or, in a green-house where 

 there are no flues, might not a lamp, or a jet 

 of gas, be kept burning night and day, under 

 a cistern of water, which would give out 

 its heat in cold nights in proportion to the degree of cold, and would 

 never become too hot in the daytime ? I know that heating frames and 

 green-houses by lamps has been tried both in France and England, with- 

 out ever having come much into use ; but I think if a mass of heat, if I 

 may so speak, were accumulated in a body of water, either circulating in 

 pipes, or at rest in a covered cistern, the effect would be quite different. — 

 Zig-zag. September 30. 1827. 



Heating Water by burning Gas. — One advantage of heating hot-houses 

 by hot water is, that they can hardly ever be overheated. The heat of the 

 water need never exceed 1 50°, and, supposing the temperature of the air 

 of a hot-house in which a cistern heated to that extent is placed to be 80° 

 or 90°, water parts with its heat so slowly that the air of the house would 

 not be greatly increased in temperature for a long time, especially with 

 the ordinary extent of glass roof. It follows, as we think, that where the 

 artificial heat of a hot-house is to be communicated to its atmosphere by 

 means of a large reservoir of water, it would not signify much whether that 

 water were heated during the day or during the night, or whether the 

 waste, however irregular it might be, was made up by an irregular supply, 

 or a supply perfectly constant and regular. Admitting the latter plan to 

 be a good one, then, in all situations where gas pipes are laid for the supply 

 of lamps, a jet of gas might be burned night and day under or within the 

 reservoir, and thus furnaces and flues entirely dispensed with. Perhaps 

 the way of procuring most heat from a jet of gas would be to cause the 

 smoke and heat of the flame to ascend through the water in a spiral tube 

 {fig. 129. p. 366), similar to the worm pipe used in distilling. If cisterns, 

 so heated, were found to give out their heat too rapidly in the daytime, 

 they might be cased with boards, with a vacuity of 6 in. between the cistern 

 and the boards. This case and vacuity would prevent the escape of the 

 heat when it was not wanted, and the boards might be removed or opened 

 in different degrees (they might open and close like Venetian window- 

 blinds) in the evenings, according to the estimated coldness of the ap- 

 proaching night. In the case of green-houses, where a very moderate 

 supply of heat is wanted, burning a jet of gas in the night would, during the 

 greater part of the winter, be found sufficient ; and, limiting the burning 

 to the same period, might probably be found adequate for pits and frames 

 of every description; possibly, also, for such plant stoves and forcing- 

 houses, for succession crops, as may be covered with straw mats, in the 



