458 THE ROLE OF CHEMISTRY IN PAINTINGS. 



be understood by examining la Madeleine of Reni, Avhicli has been in 

 the Louvre over four hundred years, that this sohition is an excellent 

 one when all the other necessary precautions are taken. This little 

 painting, 15 by 20 inches, is on sheet iron; its colors have kept all 

 their freshness, and it does not show the least trace of cracking. The 

 painting looks almost like an enamel, and has followed without any 

 deterioration all the deformations of the metal, which is, however, 

 greatly crinkled. 



Thanks to the notable progress which metallurgj^ has made in these 

 later years, one can secure to-day, and at a very fair price, thin sheets 

 of iron of many square meters of surface which seem to answer almost 

 all the needs of painters. Tlie metal suffers insignificant modifica- 

 tions in the manner of manufacture so that they constitute almost 

 perfect supports; in any case neither more or less heavy than the 

 present large frame and just as easily handled. 



