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.
Recognizing the Symptoms of an HIV Rash. 1. Check for a rash that is red, slightly raised, and very itchy. HIV rash usually causes blotches and spots on the skin, red for people with fair skin and dark purplish for people with dark skin. The severity of the rash varies from patient to patient.