CORRESPONDENCE OF RAY. 269 



but ill-natured kybes or exulcerated chilblains called 

 pernios. My reason is, because cold, but especially frosty 

 weather, aftects them much, causing such a troublesome 

 itching as we experience in chilblains ; and further, they 

 spread with little hard tumours or knots within the skin, 

 and this though I keep them constantly warm. Hence 

 I infer that the cause of them is not so much the chilling 

 of the parts affected by the external cold, to which they 

 are exposed, as the congelative particles (whether nitrous 

 or of what nature I know not) with which the air is 

 charged, drawn in by the mouth in breathing, and in 

 the lungs communicated to the blood. You will demand, 

 why th^n are these tumours excited only in the hands and 

 the feet? I answer, that the external cold doth indeed 

 concur to the generation of them : for the hands and 

 feet being the extreme parts of the body and of small 

 bulk, and most distant from the fountain of heat, the 

 heart, the blood by that it arrives there loses much of its 

 heat; and so these particles being by reason of their 

 gravity, unapt to comply with the motion of the blood, 

 it lets fall many of them (as we see warm water will 

 sustain much more salt than cold ; and as the heat dimi- 

 nishes lets it fall by degrees), which resting there, cause 

 these tumours so troublesome with their itching when they 

 are externally heated. In persons young and vigorous, 

 who abound in natural heat, and in whom the blood is 

 maintained in a brisk motion, if these parts be kept con- 

 stantly warm there are no chilblains generated, the blood 

 retaining these congelating particles, which are easily sup- 

 ported in it, and whirled about with it, till they be gradually 

 cast off and evacuated by the natural connectorics. But 

 in persons aged, in whom the motion of the blood is 

 languid, when it is sated with them, a little diminution 



of heat, which must needs follow from 



* * ,''.'.* * * 



[per]suaded and confirmed in my opinion of the nature 

 of these ulcers by the ineffectualness of all the physic I 

 have used toward'the healing and drying them up ; and 



