What are the four primary elements found in coal? 90% carbon, 3% oxygen, 4% hydrogen, and 1% sulfur. What forms of air pollution do these elements become as part of coal combustion? When coal is burned for fuel, it combines with oxygen in air to form several air pollutions. What substances are contained within coal ash?
It is an oil painting on canvas.   It is to show Picasso's anger at the bombing of the little Spanish town Guernica in 1937.  .
Therefore it seems plausible from the placing of the paintbrush in the 1934 drawing, that the Guernica spear, is also a cryptic representation of Picasso's paintbrush, partly because of its similar appearance and partly because of its connection to Picasso's remarks about painting being a weapon,