178 ANNUAL REPORT 



water is reduced to zero. If now the third element — motion — 

 be introduced, the temperature is lowered to 25° below zero. 



Snow and dilute sulphuric acid, in the proportion of 4 to 

 5, produces a temperature averaging from 50° to 90° below zero, 

 while solid crystals of carbolic acid, in passing to the form of 

 air or gas, will, by absorbing heat from adjacent bodies, reduce 

 their temperature to 148° below zero, or 180° below the temper- 

 ature of freezing water. This is the lowest possible artificial 

 temperature yet attained. 



A vessel of water subject to no exterior and disturbing influ- 

 ences, may sink in temperature several degrees below the freez- 

 ing point, and without congealing, but should the vessel now be 

 shaken lightly, or a small portion of water be removed at this 

 time, thus introducing into the mass the element of motion, ice 

 is formed at once throughout the body of water, and the process 

 of freezing thus inaugurated goes on uninterrupted until the whole 

 body of water is converted into a mass of ice. 



But the phenomena of motion does not cease with ceasing to 

 be visible to the eye. During the change from the fluid to the 

 solid form, the atoms make a final change of position requiring 

 somewhat more of space, and to meet this demand the inelastic 

 vessel is burst asunder. 



Thus we see the compound, heat and water, in two extremes of 

 status or condition. First, that in which the heat is carried to 

 a high proportionate quantity; and second, that in which heat is 

 reduced to the lowest possible proportionate quantity, and that 

 in either case the active and mechanical principle of motion 

 is present, thus fully demonstrating the close alliance always 

 existing between the elements, fire or heat and water and motion, 

 the prime resultant of all problems in mechanics. 



Water and iron are two substances entirely unlike in their 

 composition, their structure and their nature, but there is a 

 close similarity in their actions while under the influence of heat. 

 Either of them increases slightly in volume with the first addi- 

 tions of heat. Free motion is established among the atoms of 

 water almost from the moment heat is added, while free motion 

 among the atoms of iron does not take place until the mass has 

 reached a temperature of about 3,000°. If now a small per cent 

 of water be added to iron at this temperature an immediate and 

 terrific explosion follows. 



Sufficient heat is at once imparted to the water to convert it 

 instantaneously into 1,700 volumes of steam, and the molten iron 



