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DONALD F. GLEASON, MD

Arch Intern Med. 1965;116(5):649-653.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

THE HYDROGEN ion concentration of human plasma usually ranges from about 35 to 45 billionths molar. This might easily and usefully be expressed as 35 mµM to 45 mµM. In disease states it may range from about 10 mµM to 200 mµM.

Logarithms are convenient to express very large or very small numbers, particularly if these cover a wide relative range. The logarithm of a decimal fraction is a negative number which increases in size as the decimal fraction becomes smaller. It is inconvenient to retain negative numbers, so pH was defined as the negative logarithm of the hydrogen ion concentration. Two negatives yield a positive number for pH, which however, still increases in magnitude as the hydrogen ion concentration decreases.

We are so accustomed to pH notation that it seems "natural," but it is certainly a nuisance to calculate. Moreover, some properties of the hydrogen ion are not . . . [Full Text PDF of this Article]

Author Affiliations
MINNEAPOLIS

Chief, Laboratory Service, Minneapolis Veterans Hospital and Instructor in Pathology, University of Minnesota.

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