Protrude your tongue a little away from the lips. Fold the tongue like a tube. Draw in the air through mouth with a hissing sound Si. Retain the breath as long as you can hold on with comfort. Then exhale slowly through both the nostrils. Practice this daily again and again in the morning from 15 to 30 times. You can do it either on Padmasana, siddhasana Vajrasana or even if you are or walking. This Pranayama purifies the blood. It quenches and appeases hunger. It cools the system. It destroys Gulma (chronic dyspepsia), Pleeha, inflammation of various chronic diseases, fever, consumption, indigestion, bilious disorders, phlegm, bad effects of poison, snake-bite, etc. When you are caught up in a jungle or any place where you cannot get water, if you feel thirsty, practice this Pranayama. You will be at once relieved of thirst.
In the early morning, answer the calls of nature and sit for the practice. Practice Pranayama in a dry well-ventilated room. Pranayama requires deep concentration and attention. It is always better to have the practice in a steady posture. Do not keep anyone by your side to avoid distraction of your mind.
Before you sit for Pranayama, thoroughly clean the nostrils well. You can take a small quantity of fruit-juice or a small cup of milk or coffee even before the practice. When you finish the practice take a cup of milk or something light to eat after 10 minutes.
Practice only in the morning during summer. If there is heat in the brain or head, apply Amla oil or butter on the head before you take your bath. Take Misri Sharbat by dissolving sugar candy in water. This will cool your whole system. Do Sitali Pranayama also. You will not be affected by the heat.