142 ANNUAL OF SCIENTIFIC DISCOVERT. 



phorus burns in air, potassium in water, etc.). In regard to the 

 spontaneous combustion of the human body, Professor Frankland 

 showed that it was a physical impossibility, on account of the large 

 amount of water in its constitution. 



Gunnery and the Dynamical Theory of Heat. In an address at the 

 opening of the British Association, 1863, Sir W. Armstrong stated, 

 " that the science of gunnery was intimately connected with the dy- 

 namical theory of heat. When gunpowder is exploded in a cannon, 

 the immediate effect of the affinities, by which the materials of the 

 powder are caused to enter into new combinations, is to liberate a force 

 which first appears as heat, and then takes the form of mechanical 

 power communicated in part to the shot and in part to the products of 

 explosion which are also propelled from the gun. The mechanical 

 force of the shot is reconverted into heat, when the motion is arrested 

 by striking an object, and this heat is divided between the shot and the 

 object struck, in the proportion of the work done or damage inflicted 

 upon each. These considerations recently led me, in conjunction with 

 Captain Ncble, to determine experimentally, by the heat elicited in the 

 shot, the loss of effect due to its crushing when fired against iron plates. 

 Joule's law, and the known velocity of the shot, enable us to compute 

 the number of dynamical units of heat representing the whole mechani- 

 cal power in the projectile, and by ascertaining the number of units de- 

 veloped in it by impact, we arrived at the power which took effect 

 upon the shot instead of the plate. These experiments showed an 

 enormous absorption of power to be caused by the yielding nature of 

 the materials of which projectiles are usually formed; but further ex- 

 periments are required to complete the inquiry." 



THE EFFECT OF INTENSE HEAT ON LIQUIDS. 



At a recent meeting of the London Chemical Society, Mr. Grove, in 

 a paper on the above subject, first called attention to the difference ex- 

 isting between the boiling of water, under ordinary circumstances, and 

 that of sulphuric acid. He stated that the equable evolution of steam, 

 when water is boiled in an open vessel, is caused by the presence of a 

 certain amount of air dissolved in the water, and that boiling may be 

 regarded .as an evaporation into the liberated bubble of air set free by 

 the elevated temperature. In an open vessel, a sufficient amount of air 

 is continually reabsorbed, so that the ebullition goes on equally. On 

 the contrary, when water is heated in a very long tube, it boils in the 

 first instance evenly, but after the air is expelled it boils with the most 

 violent concussions ; during the regularly-recurring intervals between 

 the sudden and violent emissions of steam, the temperature rises far 

 above 212, and then a sudden explosive production of steam occurs, 

 almost resembling the discharge of gunpowder. By placing a portion 

 of water in a flask under the vacuum of a good air-pump, and heating 

 it by the transmission of a strong electric current, passed through a 

 fine platinum wire contained in the water, Mr. Grove proved that the 

 water did not boil at all, but that the whole burst up into violent con- 

 cussions at regularly-recurring intervals. When the air was exhausted, 

 ebullition occurred at intervals of about a minute, upon which a burst 

 of vapor would almost eject the contents of the flask. On this action's 

 increasing, the water would again become perfectly tranquil, and re- 



