On Cutaneous Absorption. 301 



which the test was applied. This is certain, that I 

 added several drops of a strong infusion of madder, to a 

 very small quantity of serum, and could not detect it by 

 my tests. One- sixth of the quantity of madder would 

 have been detected by the tests, in the same quantity of 

 water or urine. 



Comparing the quantity of coloured urine, together 

 with the degree of colour exhibited in the two last ex- 

 periments, I should judge that not less than twenty or 

 thirty ounces of fluid were absorbed by the skin in the 

 last experiment. But it would be very difficult to 

 come at any thing like precision on this point. 



Will it, after all, be said, that the lungs might absorb 

 the colouring part of the madder ? I think not. Every 

 woollen-dyer knows too much to raise an objection like 

 this. The following experiment, however, is in point. 

 I distilled a pretty strong infusion of madder at the 

 boiling temperature. The fluid caught in the receiver 

 was colourless as water, and did not receive any colour 

 by the addition of the alkali. Nor did the boiling 

 heat in the least injure the colour of the infusion in the 

 retort. A few drops of it in water or urine could be 

 detected by the potash in the same manner as before. 



Although the doctrine of cutaneous absorption may 

 now be considered as resting on an immoveable basis, 

 yet it remains for future experiments to show what are 

 the different substances which are absorbed, and with 

 what facility they may be made' to enter the skin. It 

 would, however, be an extrcmelv limited view of the 



6UPPL. O^q 



