574 Transactions of the American Institute. 



soon mix with the particles of all kinds conveyed by the air. This 

 compound film, covering the skin, prevents the action of water. 

 The imbricated structure of the epidermis is another cause which 

 impedes the action of water on the skin. This is so true that, 

 when water is collected under the skin by means of blistering, it 

 cannot find an issue without some violent mechanical means, such 

 as cutting or tearing open. A third cause which prevents the 

 absorption of water and the salts it contains, is the cohesion of the 

 aqueous particles themselves, for, though liquid, they are difficult 

 to separate from each other, as daily experience proves. These 

 three causes combined render the absorption of water by the skin 

 impossible. But there are causes which facilitate absorption; such, 

 for instance, is the gaseous form, which is eminently calculated to 

 penetrate the pores; thus the absorption of oxygen is the cause of 

 the pain one feels when the skin is scorched. So liquids that are 

 easily volatilized may be absorbed, especially when they have the 

 property of dissolving greasy substances; such, for example, are 

 ether, chloroform, benzine, etc. Even solids, when capable of 

 volatilization, will penetrate through the skin; camphor, musk and 

 cantharides belong to this class. Lastly, certain solids, powdered 

 and made into ointment with hog's lard, will, by friction, be 

 absorbed by the pores, because the natural fatty film of the skin 

 vdll be dissolved and converted into a sort of soap by the alkaline 

 salts, and thus become assimilated with the medicinal substance. 

 The question discussed by Dr. Scouttetten is of great interest to 

 the large class of artists who, in the prosecution of their business, 

 have to often handle photographic chemicals. 



EXPERIMENTS ON RESPIRATION. 



Pettenkofer and Voit have made further experiments in the 

 improved respiration apparatus, and have found that inore oxygen 

 is absorbed during sleep than when the person is awake, and that 

 more carbonic acid gas is exhaled by day than b}' night, and much 

 more when the person is engaged in labor than Avhen comparatively 

 inactive. On the night following a day of hard labor, there is an 

 increase over the normal quantity of oxygen absorbed. The facts 

 obsei-ved render it probable that oxj'gen is stored up in the body 

 for several hours, where it assists in the process of slow oxidation 

 of the nutriment tjiken during the day. Even on days of rest, the 

 quantities of carbonic anhydride and water eliminated are greater 

 than those which correspond to the bulk of oxygen absorbed 



