32 Laboratory Arts 



soldered and riveted with the greatest ease. As, however, it 

 soon rusts, very little time should be spent in making apparatus 

 of this material. 



Zinc is used for making water troughs and similar vessels. 

 In a chemical laboratory it is an unsatisfactory metal, being 

 attacked by acids, and by mercury. Its use as a lining for sinks, 

 or in any other capacity connected with laboratory drainage, 

 cannot be too highly deprecated. 



Copper is a familiar metal in every laboratory. Its value 

 lies principally in its high conductivity of heat and its resistance 

 to the ordinary process of oxidation. 



It is affected by the fumes of nitric and hydrochloric acids, 

 and by ammonium salts, consequently it cannot be said to 

 escape altogether the usual penalty of a laboratory atmosphere. 

 The great ductility of copper permits it to be " spun " and 

 moulded to a great number of shapes ; seamless vessels now 

 being available, making very valuable additions to laboratory 

 equipment. Calorimeters of copper, brass, and aluminium, 

 without a joint of any kind, may now be obtained from any 

 dealer in physical apparatus, and the old soldered calorimeters 

 are no longer justifiably used. Copper is used in the construc- 

 tion of air-, water-, and sand-baths, and much other laboratory 

 apparatus. Its use in sand-baths is a mistake in the opinion of 

 many teachers, the copper being liable to oxidize and scale in 

 use, causing dirty sand and frequent trouble in other ways. 



Copper rivets for the jointing of leather, and metal, are in 

 general use, its malleability enabling one to make a good joint 

 with the minimum of trouble. 



Aluminium is used in " spun calorimeters," and sheets of 

 aluminium are usefully cut up to make " clips " and " saddles " 

 for fixing apparatus to stands, base- or back-boards. The metal 

 does not easily corrode, bends with little trouble and does not 

 crack in bending at right angles as much as brass does. Its 

 appearance in this connection is in its favour. 



Owing to its lightness and freedom from liability to corrode, 

 aluminium would be much more freely used in the laboratory 

 were it possible to work it easily. Practically the only satis- 

 factory method of working aluminium is that known as spinning. 



