There are three principal fluids which circulate through the body, viz., arterial blood, venous blood, and lymph. As the blood passes out from the heart through the arteries it is strongly charged with magnetism and is very strongly acid in quality. As it returns to the heart through the veins it has expended its magnetism and its acidity has been very much neutralized. The lymph is an alkali fluid, and it circulates through the lymphatic vessels as a reserve force of vital food. The predominance of either of these fluids in the constitution greatly modifies the character and gives rise to the classification of the chemical temperaments. As every cell in the body comes in contact with an acid and an alkali fluid, we may, by estimating the relative quantities of each fluid, arrive at a very accurate judgment of the chemical condition of the body, and these elements are also valuable in estimating the amount of magnetism that will be produced by the organization through chemical action, as every cell by its contact with these fluids is constituted a magnetic battery. THE ACID TEMPERAMENT exists where arterial blood predominates. It is distinguished by convexity of features and sharpness of angles. The face is usually round in general outline and convex in profile, the forehead prominent at the eyebrows and retreating as it rises, the nose Roman, the mouth prominent, the teeth convex in form and arrangement and sharp, the chin round and sometimes retreating. The body is angular and generally convex in outline, with sharpness at all angles. This temperament is usually accompanied with great activity of mind and vivaciousness of disposition, and sometimes develops great energy and asperity. It is very likely to exhaust itself prematurely. THE ALKALI TEMPERAMENT exists where lymph is in excess over arterial blood. It is distinguished by concavity of features and obliquity of angles, or rather the absence of angles. The face is usually broad in general outline, and concave in profile, the forehead prominent and wide at the upper part, and medium in development at the eyebrows, the nose concave, the mouth retreating, the teeth flat in form and arrangement, the chin concave and prominent at the point. The body is round and inclined to corpulency, without angles. This temperament is usually well stocked with vitality, but unless actively employed is likely to become dull and overloaded with adipose tissue and lymph.