function preload() {

   img0=new Image(0,0);
   img0.src='../images/source_de.gif';
   img1=new Image(0,0);
   img1.src='../images/minerale_de.gif';
   img2=new Image(0,0);
   img2.src='../images/mineraux_de.gif';
   img3=new Image(0,0);
   img3.src='../images/source_de_r.gif';
   img4=new Image(0,0);
   img4.src='../images/minerale_de_r.gif';
   img5=new Image(0,0);
   img5.src='../images/mineraux_de_r.gif';
   img6=new Image(0,0);
   img6.src='../images/contact_de.gif';
   img7=new Image(0,0);
   img7.src='../images/contact_de_r.gif';
}