Water-soluble graphite pencils

Last night was Life Drawing and for this group, I'm working in a sketchbook - sometimes with ink but mostly with water-soluble graphite pencils. With them, a person draws - and erases- as with a regular pencil. Then, with a brush dipped in plain water, the drawing is "fixed"and also blends so that shadows become washes. It works very nicely as it involves carrying a light load on supplies. Now, one sketchbook is completed. On the reading front, I am now into volume two of the Matisse biography - Matisse the Master- up to page 173 and WWI has begun.