406 ANNUAL REPOET SMITHSONIAN INSTITUTION, 19 3 2 



always employed, and, if possible, an additional local exposure is 

 made. In these cases as much skin surface as possible is irradiated. 

 With impregnated carbons, depending on the cores and the amperage 

 employed, one can gage the dosage by watching for skin erythema 

 and the general constitutional reactions. With these one must feel 

 one's way cautiously by first using very small exposures. With a 90- 

 ampere carbon arc, beginning exposures of one-half minute are made, 

 at a distance fixed for various makes of apparatus — usually above 

 6 feet — and perhaps 20 minutes secures the maximum exposure. Al- 

 though with the Finsen arcs of thick carbons, exposures of 2 hours 

 are made, 15 minutes is the longest time with the long-flame arcs. 

 The aim has been to determine the optimal amount of skin to be ex- 

 posed. Thus, a method of exposure of only limited skin areas such 

 as the thorax or back, with a new area every other day so as to utilize 

 four parts and return to the area of the first exposure on the tenth 

 day, has given very favorable results. The skin is thus maintained 

 in a light-sensitive state, and no exposure is given during desquama- 

 tion. The question of the advisability of such a manner of irradia- 

 tion is not yet solved. 



With a new mercury-vapor quartz light, alternating current of 

 5 amperes, 110 volts, I have also made exposures purely on an 

 empiric basis, beginning with one minute at a distance of 36 inches 

 from the body, employing two exposures in front and two behind, 

 and centering over the middle of the upper and lower halves of the 

 body in order to expose uniformly as much of the skin surface as 

 possible; a fifth exposure is then made directly over the area of 

 disease to include any possible reflex depth action; a daily increase 

 of one minute is added to the exposure until a 10 or rarely 20 minute 

 period is reached front and back at this distance on all five parts. 

 The room temperature is maintained at about 70° F. Ventilation 

 is emploj^ed, so that the patient senses the movement of air. Heat 

 lights (carbon incandescent bulbs) are added, if the patient is not 

 able to endure the ventilation without discomfort. With older 

 burners, dosage is increased more rapidly. 



The quartz burner is then slowly brought nearer to the body by 

 lowering it about 1 inch every other day until it is 18 inches from 

 the skin if no redness of the skin occurs with the previous dose. 

 After this, the second intensity is frequently employed, especially if 

 the burner is one that has had considerable usage. In addition to 

 the general body exposures with the air-cooled mercury-vapor light, 

 a contact exposure is often made to a superficial focus of disease by 

 means of an applicator attached to the water-cooled mercury-vapor 

 light. 



