162 ANNUAL OF SCIENTIFIC DISCOVERY. 



Now, what becomes of the heat which seems to be shut up in a min- 

 eral substance for the space of a month ? The substance of the min- 

 eral is dilated, the distance between its molecules is enlarged, but 

 these molecules slowly approach each other again and in the course 

 of some weeks resume their original positions. "What induces the 

 change, or how does it happen that the original specific gravity is 

 not acquired immediately the substance has cooled ? Will the same 

 phenomena show itself with other families of minerals or with me- 

 tallic elements ? Such are the points which I propose to examine in 

 the next place ; in the mean time the observations I have just alluded 

 to arc proof that bodies can absorb a certain amount of heat not indi- 

 cated by the thermometer (which becomes latent), and that this is af- 

 fected without the body undergoing a change of state : secondly, that 

 they slowly part with this heat again until they have acquired their 

 original densities : thirdly, so many different substances being affect- 

 ed bv a change of density when melted or simply heated to redness 



* ^j */ L + 



and allowed to cool, it is probable this property will be found to be- 

 long, more or less, to all substances without exception." 



RESEARCHES ON BOILING WATER. 



Mr. William R. Grove, in a recent lecture on this subject before the 

 Royal Institution, after defining boiling as the complete elimination of gas 

 or air from a liquid and its transformation into vapor, expressed his 

 conviction, founded on experiments, that water never did boil as far as we 

 know now : what he termed an "everlasting" bubble of a gas always re- 

 maining behind. After showing, by means of the electric lamp, the phe- 

 nomena accompanying boiling \vater in a tube, the rising of the bubbles of 

 air from the bottom, he expressed his opinion that water could not boil 

 without air. He then proce< ded to describe experiments made in relation 

 to those of Donny, who had shown that in proportion as water is deprived 

 of air, the character of its ebullition changes, becoming more and more 

 abrupt, boiling with sudden bursts, \vhilebetweeneachburst the water 

 reaches a temperatu;e considerably above the boiling point; to do this it 

 was necessary to boil the water in a tube with a narrow orifice, through 

 which the vapor issued. If the water were boiled in an open vessel it re- 

 absorbed air, and boiled in the ordinary way. Mr. Grove illustrated 

 the difficulty experienced in entirely expelling air or gas from water by 

 boiling it under oil in a tube. Each bubble of steam which left the surface 

 of the water passed through the column of oil, becoming smaller ar.d 

 smaller during its ascent, but it never condensed without leaving a minute 

 bubble of gas, which would be found to be nitrogen. With the view of 

 testing the possibility of converting an absolutely pure liquid into vapor, 

 Mr. Grove tried bromine, but discovered in this instance that a certain 

 quantity of oxygen occupied the space above the liquid bromine: and 

 even sulphur and phosphorus strongly heated over a close vessel each 

 gave off a gas. We have no space to describe Mr. Grove's experiments 

 in relation to the decomposition of water by heat, and the mode of action 

 in the gas-battery. He expressed his own opinion that hitherto simple 

 boiling, in the sense of a liquid being expanded into vapor by heat, without 

 1 cii-g decomposed or having permanent, gas elimirated from it, is a thing 

 unknown, lie stated that close investigations into these interesting phe- 

 nomena uou!d probably 1'v.d to most important discoveries, and expressed 

 his regret at not having time to spare to continue his researches. 



