1 In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured. 2  Of the many different varieties of mercury barometers, most variations arise from different techniques for measuring the height of the mercury column.
Recognizing the Symptoms of an HIV Rash. 1  1. Check for a rash that is red, slightly raised, and very itchy. 2  2. Note if the rash appears on your shoulders, chest, face, upper body, and hands. 3  3. Pay attention to other symptoms that may occur when you have HIV rash.  4. Be aware of the causes of HIV rash.
HIV may not cause symptoms early on. People who do have symptoms may mistake them for the flu or mono. Early symptoms of HIV are called acute retroviral syndrome. The symptoms may include: 1  Belly cramps, nausea, or vomiting. 2  Diarrhea. 3  Enlarged lymph nodes in the neck, armpits, and groin. 4  Fever. 5  Headache. 6  Muscle aches and joint pain. 7  Skin rash.