866 HENRY A.-MATTILL 



disappeared. The comparative findings in a cold tub bath during which 

 both systolic and diastolic pressures are raised and pulse is slowed show 

 the great difference in the effects of the two kinds of baths on the circula- 

 tion, and they consider that a sea bath involves, in addition to the elf ect of 

 a cold bath, three factors, the salt content of the water, the mechanical 

 effect of the waves on the skin and the muscular work involved in buffeting 

 the waves. Similar data from fresh water seem not to be at hand. Blood 

 pressure values following bathing in Great Salt Lake, although obtained 

 during the bath, were normal perhaps because the factor of exercise in 

 resistance to waves was absent. 



It is a common experience that the skin feels "smoother" after a salt 

 water bath than after a fresh water bath. This may be associated with 

 modifications in skin sensitivity (Santlus). 



Effervescent Baths 



The presence of a dissolved gas in water lowers the indifferent tem- 

 perature of the water, that is, the temperature at which heat is neither 

 added to nor taken from the body. Water at 25 C. feels cool; CO 2 or O 2 

 at that temperature feels warmer (Senator and Frankenhauser). In a 

 cold effervescent bath when the body becomes covered with bubbles the 

 points of the skin in contact with gas feel warmer than those in contact 

 with water and the former also give off heat less rapidly since gas is a 

 poorer conductor than water, CO 2 only one-half that of air. However, 

 the tactile end-organs of the skin as well as the warm and cold spots are 

 stimulated (Goldscheider) and the tendency to heat loss and to secondary 

 heat production is greater in an effervescent bath because physical regula- 

 tion is prematurely broken down by the mechanical stimulus. Hyper- 

 emia of the skin, the "reaction" appears more quickly and with 

 less feeling of cold than in an ordinary bath at the same temperature. 

 After due allowance has been made for these different and variable factors, 

 it may be questioned whether an effervescent bath introduces into hydro- 

 therapy any new features beyond the possibility of further combinations 

 of the effects secured by ordinary procedures. The resultant temperature 

 effect is the determining factor. 



The original experiments of Winternitz showed that G0 2 baths caused 

 an increase in the total volume of respired air and a remarkable rise in 

 CO 2 output without corresponding increase in oxygen intake ; he explained 

 the increased CO 2 output by assuming an absorption of C0 2 by the skin. 

 During the last two decades a very considerable body of literature has 

 appeared on the effects of GO 2 and O 2 containing baths particularly on 

 blood pressure (Groedel), much of it contradictory and propagandist in 

 nature. According to Swan the influence of carbonated baths on blood 



