Chinese ink was traditionally made into solid inksticks for easy to carry and storage. The ink was then ground on an inkstone to mix with water for use. The main ingredients of this ink stick are pine soot,  scents, and binding agent. The pine soot is made from the burnt pinewood. It does not fade to the extent that western ink does when exposed to light and ancient pictures and calligraphy still retain their resilience after centuries of display. 

Blue Ink is the general name for this kind of pine soot ink stick made by the old Hu Kai Wen brand.    

Comparing to bottled Japanese blue ink, it has less blue tint but gives a thicker body as hand-ground ink. Here is a tip for you: you may use this ink stick to grind the bottled ink on ink stone to make it into a heavier paste. That is, instead of using pure water you can pull some liquid ink from bottle into the ink stone and add just a little bit water, then grind it with the ink stick. By so doing you will get the quality of traditional ground ink and the convenience of bottled ink. This well ink stick can last for long time for moderate uses.