How do i use a density in a sentence that shows it's scientific meaning?

read this excerpt from “incidents in the life of a slave girl.”

i went about my evening work with trembling steps. mr. flint twice called from his chamber door to inquire why the house was not locked up. i replied that i had not done my work. "you have had time enough to do it," said he. "take care how you answer me! "

i shut all the windows, locked all the doors, and went up to the third story, to wait till midnight. how long those hours seemed, and how fervently i prayed that god would not forsake me in this hour of utmost need! i was about to risk everything on the throw of a die; and if i failed, o what would become of me and my poor children? they would be made to suffer for my fault.

at half past twelve i stole softly down stairs. i stopped on the second floor, thinking i heard a noise. i felt my way down into the parlor, and looked out of the window. the night was so intensely dark that i could see nothing. i raised the window very softly and jumped out. large drops of rain were falling, and the darkness bewildered me. i dropped on my knees, and breathed a short prayer to god for guidance and protection. i groped my way to the road, and rushed towards the town with almost lightning speed.

what is the main idea of this excerpt?

harriet worked for a man called mr. flint who became very impatient when she did not finish her work.

harriet waited until after midnight to run down the stairs and jump out of a window into the rain.

harriet was a frightened young girl who found the faith and courage to leave her home for an unknown life.

harriet felt very nervous about running away because she did not like being alone in the darkness.

explanation:

the dog listens to mr miller