CAN BE PRODUCED BY INORGANIC MASSES, 59 



186. If ferrocyanate of potassa be tied up in a section of intestine, and immersed in a 

 solution of protosulphate of iron, Prussian blue will be deposited on one side of the 

 intestine, but not on the other ; hence it is inferred that one solution is suffered to pass 

 through the pores, but a like passage is denied to the other. 



187. If a solution of oxalic acid be placed on one side of a membrane, and lime- 

 water on the other, clouds of the insoluble oxalate of lime will form on the side of the 

 lime-water, but the other side will be pellucid. 



188. If a volume of nitrogen gas in a soap-bubble, or under any suitable membrane, 

 be exposed to atmospheric air, decomposition of that air will result, its oxygen passing 

 through the membrane to form atmospheric air with the nitrogen within. 



189. If a quantity of commercial alcohol be tied up in a bladder, and freely exposed 

 to the air, the water in union with that alcohol will pass through the pores of the blad- 

 der, and, gradually evaporating away, will leave the alcohol much stronger. 



190. And, lastly, which is by far the most remarkable of these phenomena, if a tube, 

 the extremity of which is closed with membrane, be filled to a certain height with 

 distilled water, and there be placed in it a few iron nails, on adjusting it hydrostatically, 

 and suffering it to remain for a time in a solution of sulphate of copper, the membrane 

 will apparently decompose the solution of the metallic sak, the base of which, in a 

 deoxidized state, will remain attached to the under side of the membrane, but the acid 

 and oxygen will traverse it, and be removed by uniting with the iron. 



191. The body of evidence here furnished would go to show that membranes possess 

 remarkable habitudes with respect to liquids, and, accordingly, it has been brought 

 forward as the foundation of many physiological hypotheses. Nay, more, from hence it 

 has been assumed that these were in truth nothing more than manifestations of that 

 principle of vitality which is supposed to be the result of organization. A power, 

 known under the name of endosmose, distinct from all other known agents, has been 

 created, its especial office being to bring about certain molecular changes, in a way re- 

 sembling outwardly, but essentially differing, from those of chemical affinity. 



192. The error of this position might readily have been detected. We surely should 

 not regard that as a specific force of vitality which is possessed by inorganic matter ; 

 yet, in the outset of the original experiments on the subject, it was found that alumina 

 exhibited the same action as bladder, though in a feebler degree. As to the amount of 

 force, with that we have nothing to do ; for, no matter in how small a degree soever it may 

 be that alumina possesses this character, the mere fact of possessing it at all goes to show 

 that it is not a consequence of organization, or an evidence that the substance exhibiting 

 it has ever been moulded by the powers of life. 



193. The verification of Dutrochet's experiment with alumina becomes, therefore, a 

 matter of the greatest importance ; its extension to other inorganic substances would de- 

 cide the point, and separate at once the power by which infiltrations take place from 

 the powers of vitality. It has, however, been stated that those minerals in which this 

 property has been observed possess it in a low degree. Some chemists have extended 

 this observation, and class with alumina other bodies of a porous texture, as certain varie- 

 ties of slate. But many experiments that have been made on this point have led to er- 



