What is this waste called when it comes from the surface of the skin?--"Perspiration." When does the perspiration flow through the pores of the skin?--"All the time, if the skin is healthy." Why do we not always see the perspiration which passes through the pores?--"Because it does not always form drops on the surface of the skin; it generally passes off in very fine particles." What becomes of the fine or minute portions of perspiration which pass from the body?--"Some of these portions are absorbed by the clothing; some pass into and mix with the air around us." What effect does the perspiration produce on the air and the clothing?--"It soon makes the air unfit to be breathed, and the clothing unfit to be worn." What is necessary if you would have a healthy skin? [See Formula.] Why must you wear clean clothing?--"That there may be nothing impure in the clothing for the pores of the skin to absorb." Why should you breathe pure air?--"Because air purifies the blood, and pure blood is necessary to make a healthy skin." How does drinking alcoholic liquors hurt the skin?--"It makes the blood impure, and impure blood makes unhealthy skin." In what other way does drinking these liquors hurt the skin?--"It gives the skin too much work to do." How does it give it too much work to do?--"It makes more waste substance to pass from it through the pores, in the form of perspiration." In what other way does drinking alcoholic liquors hurt the skin?--"It makes it a bad color." How does it make the skin a bad color?--"It stretches the little blood-vessels of the skin, and makes them too full of blood." See Appendix. * * * * * [Illustration: THE HEART.] A, the right ventricle; B, the left ventricle; C, the right auricle D, the left auricle; E, the aorta; F, the pulmonary artery. * * * * * PART VIII. FORMULA FOR THE LESSON ON THE HEART AND THE CIRCULATION OF THE BLOOD. 1. My heart is shaped like a cone, and placed in my chest near my breastbone, with its apex pointing downward to my left side. It beats about seventy times a minute, sending out about two ounces of blood at every beat. 2. The blood when pure is of a bright red color; it is a liquid made from food and drink. 3. It passes from my heart to all parts of my body, through pipes called arteries; these arteries spread out through the body like branches from a tree. 4. As the blood flows from the heart, through the arteries, it gives nourishment to every part of the body, and carries away the impurities it meets, which makes it black and thick; when it comes through the veins, back to the heart, it is not fit to be used, so it goes to the lungs to be purified by the fresh air; then it returns to the heart to be sent again throughout the body; this happens once in from three to eight minutes, and is called the circulation of the blood. 7. If I would be healthy, my blood must be pure and circulate freely all the time.