Scientific Lectures. 67 



end of a closed tube, containing vapor, and containing water in a 

 bulb at tbe upper end, and the condensation of the vapor, from the 

 abstraction of the heat by the freezing mixture, in its turn abstracted 

 the heat from the water in the bulb above so rapidly that it was 

 frozen solid. He then illustrated the heating of houses by hot water 

 pipes, showing that the heated water would rise from its being lighter 

 than that not heated, and thus a circulation of water never heated 

 above the boiling point, and therefore not liable to bm-n the atmos- 

 phere by charring particles of dust in it, would be constantly main- 

 tained. He proceeded to speak of the chemical constituents of water, 

 being two atoms of hydrogen and one of oxygen. [These two gases, 

 which have never been reduced to liquid form b}'' mechanical power, 

 would readily unite by the magical power of chemical combination, 

 and form that wonderful matter which we call water. The ancients, 

 in their philosophy, said the earth is composed of four elements, earth, 

 water, air and fire. We may interpret this under the light of modern 

 science thus : Earth is the solid, water is the liquid, air is the gaseous 

 condition of matter, and fire is the force that converts them all from 

 one condition into the other. "VVe have in water the solid ice, solid 

 and permanent as granite, so long as the temperature is unchanged. 

 We have in water an inelastic, mobile, transparent fluid. We have 

 in water the perfectly elastic invisible gas which we call steam. 

 Although we cannot, by mechanical means, compress tlie gases which 

 constitute water into liquids or solids, yet by their union we can 

 condense them into water ; and we can, by their union, produce the 

 highest degree of artificial heat which it is in the power of man to 

 produce mechanically. [Two vessels, one containing hydrogen and 

 the other oxygen gas, were connected with a single tube. The 

 former, being turned and lighted, produced an ordinary flame (the 

 gas not being pure), but, upon turning on the oxygen gas, the two 

 produced a much whiter and more brilliant light. Placing in the 

 blaze a mass of cold iron, the water produced by the union of the 

 gases was condensed upon its surface, falling from it in drops. He 

 next placed in the blaze a slender bar of steel, and the heat was so 

 great as to burn the steel, scattering it in a shower of intensely 

 brilliant sparks.] (Applause.) These two elements, by their 

 collision, produce an amount of heat, as a mode of motion, 

 which is beyond that which we can produce by any other artificial 

 means, which is purely mechanical. We can, indeed, by this vol- 

 taic circuit, acting chemically, produce a current of electricity, 



