Read the passage given below and answer the questions (129 - 135) that follow.

Lack of self-control has brought grief to more people than any other shortcoming known to the human race. Every successful person must have some sort of a balance wheel for his or her emotions. When a person becomes extremely angry, certain glands triggered by negative emotions begin to empty their contents into the blood and if this is kept up for more time, it will result in serious damage to the entire system, sometimes leading to death. The blood coagulates at that time. Nature created this system for the protection of the young human race during the savage stage of development, when anger usually preceding a fight might mean opening of the veins and loss of blood.

There is a reason of developing self-control. One who lacks self-control may be easily mastered by one who has such control. Success in life is very largely a matter of harmonious negotiation with other people and this requires self-control in abundance.

The author of the ‘Law of Success Philosophy’ once observed a long line of angry woman in front of the ‘Complaint Desk’ of a large Chicago department store. The young woman who was hearing the complaints, kept cool and smiled all the time notwithstanding the fact that some of the women were very abusive. One by one, this young woman directed the women to the right department and she did it with such poise that it caused the author to walk up closer where he could see just what was happening.

Which one of the following words is most similar in meaning to the phrase ‘liquid getting thick’ as used in the passage ?