ZOOLOGY. 267 



ABSORBIXG POWER OF THE HUMAN SKIN. 



Dr. Murray Thompson observes : " For the last sixty years physi- 

 ological 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 authors holding that such salts as iodide of 

 potassium readily reach the blood through the skin, when applied in 

 the form of a bath containing that salt ; while others hold that absorp- 

 tion, under such circumstances, never takes place. 



" My experiments were all made on my own person at various inter- 

 vals during the last two years. Six of them were made on as many 

 successive nights, so as to try if frequency of bathing rendered 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 temperatures ranged 

 usually from 90 to 98. The salt to be tried was then dissolved and 

 mixed" with the water. The time in the bath was noted; it varied 

 from half an hour to one hour and a quarter. The whole body was 

 immersed, excepting the head and neck. All the urine voided in 

 twenty-four hours after each bath was collected and concentrated, then 

 tested for the substances experimented on. Six baths were taken, in 

 which iodide of potassium was dissolved. The quantity of the salt va- 

 ried from 200 to 1300 grains. Five baths, in which quantities of fer- 

 ro-cyanide of potassium, varying from 1400 to 5000 grains, were dis- 

 solved. Four baths were taken, the water of which was rendered 

 strongly alkaline by soda. The result of these fifteen experiments 

 was, that I could not find that any of the substances in the baths passed 

 through the skin into the blood, so as to be found in the urine ; the 

 soda baths did not render it alkaline, nor could I detect the other salts 

 in it ; and it is to be noted that the tests for them were extremely deli- 

 cate. 



" The general conclusion which my experiments lead me to are, 

 1. That though not denying that absorption by the skin of aqueous 

 solution does take place, yet it seems to be the exception and not the 

 rule. 2. That medicated warm baths, whether natural or artificial, do 

 not appear to owe any virtue they may have to the substances dis- 

 solved in them reaching the blood through the skin. At the same 

 time, as there are other ways by which one can conceive such baths to 

 operate on the system, it is not to be concluded that, because absorp- 

 tion may not take place, such baths are useless as therapeutic agents.'* 

 Proc. Royal Soc. Edinburgh. 



ACTION OF DIFFERENT MEDICINES ON THE MENTAL FACULTIES. 



" All stimulant and exciting medicines increase the quantity of blood 

 that is sent to the br'ain. If this quantity exceeds a certain amount, 

 then most of the faculties of the mind become over-excited. Never- 

 theless, the degree of this action is observed to vary a good deal in 

 different cerebral organizations ; and it is also found that certain stim- 

 ulants exercise a peculiar and characteristic influence upon special or 

 individual faculties. Thus ammonia and its preparations, as well as 

 musk, castor, wine, and ether, unquestionably enliven the imaginative 



