PH is a measure of the hydrogen ion concentration in a substance. Water is considered to be neutral with a pH of 7. The descending range from 6 to 1 is the acid part of the pH scale, with 1 being the strongest acid. The numbers 8-14 is the alkaline scale, with 14 being the most alkaline or basic substance. The pH of blood is between 7.34-7.45. The pH of urine is slightly acidic at 6. Saliva has a pH range of 5.6-7.9--however, usually around a pH of 6. Low pH corresponds to high hydrogen ion concentation and vica versa.