CHEMISTRY. 163 



Arrangement of Particles. 



The particles of matter can change their arrange- 

 ment, (as from being flexible to brittle or crystalline,) 

 without losing their solid form. 



The Freezing and Boiling Points. 



The two unalterable points of temperature are, in 

 the first instance, when ice becomes water, and in the 

 second, when water becomes steam, and have been 

 universally adopted by the various constructors of 

 thermometers for the graduation of those instru- 

 ments ; but the space between them has been dif- 

 ferently divided by different persons. 



Reaumur divides the space between the two points 

 above mentioned into 80 degrees, placing at freez- 

 ing, and the 80th degree at the boiling point. 



Fahrenheit divides the above space into 180 de- 

 grees ; but the cypher (0) he places 32 degrees below 

 the freezing point, (the cold of a mixture of snow 

 and common salt,) so that the freezing point is at 

 32, and the boiling point at 212. 

 Reaumur 80) 180 Fahrenheit. 



2J of Fahrenheit equal 1 of 



Reaumur. 



Plus 20 of Reaumur is 20 multiplied by 2J=45 

 add 32=77 of Fahrenheit.* 



By adding salt to water, in a still, its boiling point 

 is raised a few degrees, and the boiling point is 

 lowered in proportion to the elevation above the 

 surface of the earth. 



Thermometers. 



Spirit of wine thermometers are the best for mea- 

 suring very low temperatures, as that fluid never 

 freezes; whereas the low temperature at which it 



* Or multiply the degrees of Reaumur by 9, divide the pro- 

 duct by 4, and add 32. 



