234 



♦ KNOWLEDG 



[March 20, 1885. 



Barruel, Collard di Martigny, Brunner, Regnault, Reiset, 

 Valentin, and others, have made experiments proving the 

 evolution of carbonic acid and nitrogen gases from the 

 ikin. They collected these gases and analysed them. 



I find that, wheuever I take a warm bath, and remain for 

 a short time reclining in the water, bubbles of gas run up 

 my back and come to the surface of the water. If I then 

 rub my hand? along the surface of my body, especially the 

 sides or the back, a multitude of minute bubbles are 

 poured upwards, producing quite an effervescence. I .sup- 

 pose that such is the case with other people, and therefore 

 suggest a repetition of this simple experiment to my 

 readers. They should remain quite still for about five 

 minutes, and then make the observation and experiment 

 above described. I find that the hotter the water the more 

 striking is the result, as though the heating of the bodv 

 promotes the formation of the gas. I have tried it with 

 water paiufully hot. 



The crucial question in reference to this problem is 

 whether this expiration of gases by the skin is performed 

 merely in exchange for gases previously inspired, as in the 

 longs, where we inspire a given bulk of air (oxygen and 

 nitrogen) and expire the nitrogen unchanged, and some 

 carbonic acid in exchange for some of the oxygen, the 

 expired cirbonic acid having the same bulk (allowing for 

 diflerences of temperature) as the inspired oxygen which it 

 replaces. Such being the case, no heat is rendered latent 

 by this pirt of the transaction. 



My experiment in the bath, so far as it goe>, indicates 

 an expiration under circumstances excluding the possibility 

 of corresponding inspiration by the skin. I say " so far as 

 it goes," being fully aware that to prove or disprove this 

 generally deniands an amount of delicate and careful 

 research which I cannot afford to undertake. The experi- 

 mental investigations that have been made are extremely 

 interesting; but I am notable to find a record of any 

 directly devoted to the elucidation of this question. Eegnault 

 and Reiset, by means of a very elaborate apparatus, figured 

 in Valentin's '■ Physiology," CDllected all the prodncts of 

 respiration and transpiration from a dog confined in a 

 receiver and supplied with measured quantities of air. 

 But these and other similar researches leave open the 

 question of whether the blood, in passing through the 

 hundreds of miles of capillary vessels of the cuti?, may, or 

 may not, when raised a little above its normal temperature, 

 give out carbonic acid and nitrogen, which has been pro- 

 duced by reactions among some of its liquid or solid 

 constituents. 



I think that it does ; but thus is merely an opinion based 

 on presumptive evidence, and such opinion is not science, 

 it is merely suggestion that may lead to science. 



I may describe one observation made on myself which is 

 curious and particularly suggestive. I have on my left 

 hand, arm, and breast an abnormal development of super- 

 ficial blood-vessels, a " wish mark," as it is called, of extra- 

 ordinary area. It covers the thumb and fore-finger, half 

 the i>alm, and about one-third of the back of my left hand, 

 continues as a broad band — from two to three inches wide 

 — up the whole length of my arm, and then spreads out on 

 breast, neck, and part of shoulder. I have seen a large 

 number of such " marks," but no other so large. There is 

 no swelling of the skin, no abnormal sensitiveness, but 

 simply an exaggerated vascular development of the cutis. 



That such is the structure is proved b\ the red colour, 

 although the cuticle is colourless, like that of the lips ; 

 by the experiment of pressing any part so as to squeeze 

 away the blood, when it becomes of normal skin colour by 

 this retreat of blood, and immediately regains its deep red 

 colour as the blood returns ; also by the fact that a slight 



wound bleeds profusely, far more so than a corresponding 

 wound on other parts of the skin. 



The blood diffused over this large surface is subject to 

 remarkable changes. Sometimes it is dark purple venous 

 blood, approaching to blaikness, the livid hue of a cholera 

 victim in the last stage of collapse. At other times, it has 

 the brilliant colour of purely arterial blood. Between these 

 it assumes various tints of crimson. The changes are un- 

 accompanied with any personal inconvenience beyond a 

 slight sensation of numbness when the purple condition is 

 fully displayed. 



These variations correspond to variations of tempera- 

 ture. In cold air or cold water it is purple ; in hot air or 

 hot bath, scarlet, with intermediate gradations according 

 to temperature. 



But this is not all. I can localise the colour at will. 

 When my hand and arm have become purple by exposure 

 to cold, I can redden the thumb or the finger only, by 

 dipping it in hot water or otherwise subjecting it to a tem- 

 perature a little above normal blood heat. 



I find that if I expose myself to a degree of cold suffi- 

 cient to fill these superficial vessels with venous blocd of 

 dark purple colour, and then take a warm bath with this 

 purple surface completely immersed, the blood becomes 

 arterialised and bright red, this change being accompanied 

 with the evolution of the gas-bubbles above described. 



In this case there can be no cutaneous inspiration, but 

 there does appear to be an expiration of gas, and there cer- 

 tainly is removal of carbon, either by oxidation, mechanical 

 exchange, or dissociation. The change may be simply 

 mechanical ; it may be that, when cooled, the capillary 

 vessels are congested, and the flow of arterial blood re- 

 tarded, while, on the other hand, the warmth may relax 

 these vessels, and enable the circulation to proceed more 

 rapidly. This is the most direct and plausible explanation, 

 but it does not improve when more searchingly examined. 



Whether this superficial circulation be slow or rapid, the 

 blood in the capillaries comes from the arteries. It was 

 red arterial blood immediately before entering them. What 

 occurs upon the surface to convert it into venous blood 

 when exposed to low temperatures ' If the skin acts like 

 the lungs, if the carbonic acid proved to be expired from 

 tho skin is simply the original oxygen previously inspired, 

 and thereby combined with carbon, this action shoidd occur 

 most vigorously when the skin is doing its warming work, 

 as such oxidation is a heat-evolving process, and it should 

 be more effective when the blood remains exposed for the 

 longest period — i.e , when the congestive action is the most 

 effective ; but exactly contrary is the case. It is just when 

 the skin is doing the work of cooling the body that the 

 blood is brightest on the surface. 



It must be noted that what I described as occurring so 

 strikingly on this tissue of exaggerated vascularity also 

 occurs, but less visibly, on the normal skin. The lips, the 

 nose, the cheeks, the finger-ends turn blue when exposed to 

 extreme cold, and become florid when excessively heated. 



My question now reduces itself to this definite form : Is 

 the carbonic acid evolved from the skin a product of internal 

 combination of solid or liquid oxygen yrith solid ot liquid 

 carbon 1 If so, the expansion from the solid or liquid to 

 the gi«eou3 form accounts for the cooling action of the skin, 

 under conditions where the mere superficial evaporation of 

 water is insuflicient. 



But some of my readers may say that oxygen is only a 

 gas, having seen it in this form on lecture tables, and read 

 of it as "oxygen gas." This is a popular error. O.xygen, 

 like every other known element, may exist in all the three 

 states of solid, liquid, and gas — does thus exist. The simple 

 facts that eight-ninths, or above 88 per cent, of the water of 



