

XTV SIMPLE CHEMICAL OPERATIONS 213 



out as a powder. This insoluble powder is called a, precipitate, and 

 is said to be precipitated. 



Solution of Liquids. EXPT. 206. Shake up a little water 

 and ether. Observe the separation into two layers ; ether 

 above and water below. Pour the mixture into a funnel the 

 bottom of which is closed by your finger. Allow a little of 

 the lower liquid to run into a test-tube. Insert into the test- 

 tube a cork fitted with a glass tube. Boil the liquid and apply 

 a light to the tube, and observe that an inflammable gas is 

 at first evolved, but after a while only steam passes off. 



The lower layer of water hence contained a quantity of dissolved 

 ether, while it may be also proved that the upper layer of ether 

 contained dissolved water. 



EXPT. 207. Add alcohol to water, and shake. Observe that 

 they do not separate into two layers, but form one liquid. 



When liquids, as in the case of alcohol and water, form one 

 homogeneous liquid, they may be said to be mutually soluble in 

 all proportions. In such a case the liquids are said to be miscible 

 or to mix with one another. 



Hence ether and water are mutually soluble but do not mix. 



Mixtures and Compounds. Substances which contain more 

 than one element may be either compounds or mixtures, and 

 the difference between these will be best understood by perform- 

 ing the following experiment : 



EXPT. 208. Mix together some copper filings and powdered 

 sulphur, and examine the result, which is a mixture of copper 

 and sulphur. See that its colour lies between the yellow of 

 sulphur and the red of copper, and that the particles are 

 quite distinct. Wash a little in a gentle stream of water, and 

 observe that the sulphur gets washed away more readily than 

 the copper, leaving the latter as a residue. Shake up with a 

 little of the liquid known as carbon disulphide, and see that 

 the sulphur dissolves but the copper is left ; pour off the 

 solution and allow it to evaporate, and observe that the 

 sulphur is left. 



Now again mix the two ingredients in a porcelain crucible, 

 using a weighed quantity of copper, and heat either in the 

 open air or in a draught cupboard. Observe that the sulphur 

 melts and some burns away. Add more sulphur, and again 



