564 
tion of water from the sea to the land, and from the land back to 
the sea, so there is one of saline matter, tending to prevent the per- 
fect exhaustion of the soil, and to favour the growth of herbage on 
our downs and fells, and of shrubs and trees, where manure never is, 
and never has been employed. 
Whilst in the economy of nature this diffusion is presumed to 
act beneficially, on the works of man it seems to act in an opposite 
manner, — being rather destructive than preservative, — rain promot- 
ing the decay of all, or almost all, inanimate objects of a perishable 
kind exposed to its influence, and this mainly by its saline contents. 
3. Observations on the Absorbing Power of the Human Skin. 
By Murray Thomson, M.D., F.C.S., Lecturer on Chemistry, 
Edinburgh. Communicated by Dr Douglas Maclagan. 
For the last sixty years physiological and other authors have been 
maintaining two very opposite views in regard to the absorption by 
the skin of substances dissolved in the water of baths. Some au- 
thors holding that such salts as iodide of potassium readily reach 
the blood through the skin, when applied in the form of a bath con- 
taining that salt ; while others hold that absorption, under such cir- 
cumstances, never takes place. Among those who hold the affirma- 
tive view, I may mention Braconnot, Madden, O’Henry (fils), Carpen- 
ter, Chevallier et Petit ; and among those who hold the opposite 
opinion, Currie, Seguin, Lehmann of Leipzig, Kletzinsky. 
This long lasting difference of opinion sufficiently indicates, I 
think, that the subject is surrounded by difficulties. I do not pre- 
sume, therefore, that the observations I have made settle the ques- 
tion, they are only intended as a contribution to our knowledge on 
the subject. 
My experiments were all made on my own person at various in- 
tervals during the last two years. Six of them were made on as 
many successive nights, so as to try if frequency of bathing ren- 
dered the skin more permeable. The general method of making the 
trials was this : — Into an ordinary bath, a measured quantity of warm 
water was let, the temperature of which was recorded. Means were 
taken to keep the heat constant during the experiment. The tem- 
peratures ranged usually from 90° to 98°. The salt to be tried was 
then dissolved, and mixed with the water. The time in the bath 
