MODERN USES OF THE METAL ALUMINIUM 629 



without effect on aluminium but advantage has not been taken 

 of this fact to any great extent at present. 



Of far greater importance is the fact that of all the common 

 metals aluminium is the least attacked by the higher fatty acids 

 of which the bulk of the vegetable and animal oils are composed 

 (G. A. Emery, Report of the U.S. Dept. of Agric, p. 265, 1909). 

 Immense quantities of these oils are now converted into food- 

 stuffs in the form of margarine and similar products and it 

 has been found that aluminium is the most suitable metal to 

 use in the construction of the plant required. Not only do 

 the advantages of colour and immunity from toxic effect apply 

 in full force but the metal is actually unattacked by these 

 materials, some of which, such as oleic acid for instance, 

 corrode other metals with great rapidity. 



In the foregoing account no attempt has been made to 

 enumerate all the uses to which aluminium is being put in the 

 chemical trade ; only a few examples have been selected to 

 illustrate properties of the metal of which advantage is being 

 taken in various industries. Though these properties have long 

 been recognised, aluminium has been used by chemists only to a 

 very limited extent on account of the difficulty of uniting sheets 

 of the metal, which until quite recently prevented the manufac- 

 ture of any but small articles of aluminium such as domestic 

 utensils or such chemical vessels as could be made in the shape 

 of castings. Aluminium is the most electro-positive of all the 

 metals used in the industries and in consequence suffers corrosion 

 when in contact with other metals with extraordinary readiness. 

 Inventors of solders for joining aluminium have invariably split 

 on this rock. It is usually considered impossible to solder 

 aluminium but this is by no means the case. Aluminium can 

 be soldered quite readily but the soldered joints corrode rapidly 

 owing to the fact that electrolysis is induced at the joint by the 

 contact of the metal and solder. On the other hand, aluminium 

 cannot be riveted so well as other metals, on account of the soft- 

 ness of the metal, a difficulty not readily overcome ; the rivets 

 are apt to draw out, giving rise to leakage, especially under the 

 influence of temperature variations and vibration. Quite recently 

 means have been found to apply the lead burner's method of 

 jointing to aluminium. A lead burner fuses two sheets of lead 

 together without the interposition of any foreign metal. The 



