For many years we have had accurate chemical methods for the detection of small amounts of arsenic in tissue. Studies have been made chemically and pathologically of every organ and tissue in the body following the various methods of arsenical administration. This paper will deal with a microchemical method for the study of arsenic in relation to the tissue cells. The existence of a satisfactory method offers a way to study the physiologic and pathologic effects of arsenic in several rather obscure conditions, such as arsenical keratoses, pigmentation and dermatitis, and the rôle played by arsenic in the production of epithelioma in psoriatic lesions.
In this paper will be given a detailed description of the method with controls and a study of arsenical keratoses and pigmentation. Justus,1 in 1905, first employed this method and came to the conclusion that arsenic administered by mouth enters the blood stream in combination with