How does Mark Salzman use imagery in Iron & Silk?

Imagery:

"Dishwater and refuse were thrown casually out of windows, rats the size of squirrels could be seen flattened out all over the roads, spittle and mucus lay everywhere, and the dust and ash from coal -burning stoves, heaters and factories mixed with dirt and rain to stain the entire city an unpleasant greyish-brown."

"He pulled his ink-stone and tray of brushes near him and showed me how to improve the strokes. Though he could barely move his fingers, all of the rigid with arthritis, he managed to wield the brush with extraordinary fluidity. He took frequent pauses to rest, wiping the sweat from his forehead and throat and closing his eyes to recover from dizziness."