SYNTHETIC CHEMISTRY. 45 



unit, and the chemist unaided can trace the work no further. A new 

 set of forces apparently comes into play, and whether we say this new 

 agent is vital force, or prefer to hold fast to scientific accumulations 

 of facts and methods of thought, and regard the new mystery as but 

 the result of new or changed conditions, it is equally evident that the 

 province of pure chemistry ceases, for this limit was long ago self- 

 assigned by the science, and indeed exists in a latent form in all its 

 definitions. 



Doubtless, either biology, or some as yet unspecified portion of 

 science, drawn from the provinces of chemistry, physiology, anatomy, 

 and physics, will take hold of this problem and solve it ; to a certain 

 extent is doing so now, and thus far the little light which has been 

 gained seems to indicate the unbroken operation of uniform law acting 

 through the known physical forces. Perhaps under this heading com- 

 mon gun-cotton ofiers one of the most striking examples. The cotton- 

 fibre is an elongated cell, it is of course both vegetable and a special 

 functional organ, and is therefore outside of what was above spoken 

 of as the limit of pure synthesis ; nevertheless, by the simple operation 

 of immersing it in strong nitric acid, the properties of the tissue are 

 remarkably changed. It has become highly combustible and explo- 

 sive, and also soluble in a mixture of alcohol and ether. Now, the 

 chemical change has consisted in a bodily removal of hydrogen, and 

 the insertion into its place of a heavy red compound gas, and yet the 

 shape, color, and texture of the cotton-fibre are so little altered that 

 none but an expert can perceive any external change. Moreover, by 

 a reverse process, gun-cotton can be changed back again into the or- 

 dinary article. It is, then, possible to most profoundly alter the chem- 

 ical structure and properties of one of these organic cells without visi- 

 bly changing its individual shape. 



On the other hand, when gun-cotton is dissolved in ether, it becomes 

 collodion, and when this solution is evaporated the vegetable tissue is 

 left, not in its original fibrous form, but as an amorphous film ; so 

 here we have the cellular characteristics utterly destroyed by an agent 

 which is not regarded as exerting any chemical action at all ; and, by 

 analogy, we may infer that the specialized forms of organized bodies 

 are not therefore the necessary results of their atomic structure only. 



Another example of the same kind is the facility by which certain 

 crystals may be made to take on either an amorphous or an apparently 

 cellular form. It is only necessary to add gum, or some other muci- 

 laginous material, to the water in which they have been dissolved, to 

 have them appear, on solidifying in this anomalous way, all their beau- 

 tiful sharp angles and edges lost in a formless mass or in rounded 

 nodules, like many of the renal and vesical calculi. 



But this paper has already reached the limit of facts, and has per- 

 haps entered too far into the region of speculation. In the contro- 

 versy now going on, as to the spontaneous generation of life, some of 



