Mitchell on the Penetrativeness of Fluids. 321 



This is well proved by his latest experiment, in which having raised 

 a column of mercury by the penetration of water into a solution of 

 gum Arabic to twenty-eight inches, and while still rising, he replaced 

 the external water by a solution of gum Arabic, when an immediate 

 ascent was observed. The substitution of clean water again caused 

 an elevation of the column. 



On the whole, captivating as is the method, and elegant as are 

 the experiments, of this little volume of M. Dutrochet, it does not 

 bring additional support to his doctrine of endosmosis. Yet what- 

 ever may be the issue of the experimental investigation to whose 

 rigid scrutiny this most important subject is committed, the philoso- 

 pher and physician can scarcely find language adequately to express 

 the obligation, the high obligation, under which science has been 

 laid by the elegant labours of M. H. Dutrochet. In him we dis- 

 cover the punctum saliens of a principle which is the master spirit 

 of animal and vegetable motion, the ruling power of chemical 

 science, the governing influence of atmospheric composition, the 

 presiding genius of respiration, circulation, and nutrition, the cause 

 of disease, and the restorer of health. But whatever may be now his 

 fame, how little is it compared to that which may be anticipated for 

 him by one who takes even a careless view of the mighty field of novel 

 observation just redeemed from the rich wilderness of nature ! This 

 tribute is paid the more unhesitatingly because it is due, and because 

 I have so freely criticised and censured where the cause of science 

 and truth demanded severity. It is in great men, and in great dis- 

 coveries, that blemishes are most ungraceful and most injurious. 

 The very magnitude and extent of the principle for whose detection 

 we must thank Dutrochet, give a fearful importance to the slightest 

 coextensive errors. 



September l$th, 1830. 



