82 DIRECTIONS FOE PERFORMING, ETC. 



the flame of the spirit-lamp. The metal will almost instantly 

 ignite, when it may be removed and held up to the view of the 

 class until the Mg is consumed. 



124. To make a saturated solution of alum, drop crystals 

 of the salt into boiling water, until a drop of the liquid taken 

 out on the end of a glass rod and put on a bit of glass will 

 crystallize as soon as it cools. 



134. Fill a test-tube nearly full of water. Pour in it a few 

 drops of the solution of sulphate of copper. Add ammonia, 

 and a blue precipitate will be formed. Notice the change from 

 green to blue. The sulphate of copper may be readily made 

 for this experiment by covering a copper cent with dilute oil of 

 vitriol. This experiment may be made to show the divisibility 

 of matter by weighing the cent, then seeing what proportion of 

 the whole solution you use, and then experiment to find what 

 quantity of water can be taken and yet have the blue color 

 perceptible in the ammonia test. 



185. Fill a test-tube one-sixth full of sweet oil, add a little 

 ammonia, and nearly fill with water. The constituents remain 

 separate. Shake thoroughly, and they will combine, forming 

 a thin, soapy liquid. Add an acid, and they will dissolve part- 

 nership at once. 



SUGGESTIONS. 



Melted snow, or very clear rain-water, will answer the place 

 of distilled water in making solutions, &c., for experiments. 

 Whenever corks leak gas they may be wrapped with thin strips 

 of wet paper to make them fit more tightly, or the entire 

 nozzle may be smeared with tallow, or covered with sealing- 

 wax, if heat is not used. In that case a little plaster of paris 

 may be wet up and quickly applied. The experimenter will 

 find a retort-stand for holding the retorts, a test-tube holder, a 

 set of tin cork-borers, several Florence flasks of different sizes, 

 the copper retort for making oxygen, and the gas-bag, with 

 its tubing and connectors, almost indispensable. After these, 

 the compound blow-pipe is of the greatest value. A few drops 

 of a solution of magenta (i dr. in a gill of HO) will color the 

 water beautifully, and add to the effect of certain experiments. 



