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.
Skin, mouth, genital symptoms â One characteristic feature of acute HIV infection is open sores or ulcers. These sores or ulcers can develop in the mouth, the esophagus (the tube that extends from the mouth to the stomach), the anus, or the penis. The ulcers are usually painful.