LIMITS OF OUR ARTIFICIAL AIDS. 213 



smell in recognising the odour of musk is probably even 

 much more delicate than this. 



There are limits to our experiments in every direction. 

 Notwithstanding the apparently extreme delicacy of our 

 various means of detecting and measuring substances and 

 forces, they fall extremely short of what is necessary in 

 order to detect many molecular phenomena ; and our arti- 

 ficial aids may be said to be altogether inadequate. 

 Nearly every method of detecting and measuring sub- 

 stances and forces remains to be further and immensely 

 refined. According to Sorby, we have already, in conse- 

 quence of the properties of light, nearly reached the limits 

 of the powers of the microscope ; and to be able to see the 

 ultimate molecules of organic bodies would require us to 

 use a magnifying power of from 500 to 2,000 times 

 greater than those we now possess. 1 



It is chiefly by great refinements of scientific methods 

 that we can hope to detect minute residual phenomena, 

 and discover those less obvious truths which are the most 

 universal, and which will probably disclose to us the great 

 principles of nature co-ordinating the many lesser truths 

 we at present know. 



A great advance in degree of refinement of scientific 

 method is sometimes a result of an apparently very trivial 

 circumstance, such for example as the use of platinum 

 vessels in enabling more accurate chemical analyses to 

 be made. If we could cause every substance to form its 

 equivalent of ammonia, as we do at present with nitrous 

 and nitric acid, we should at once obtain in an indirect 

 manner an extremely delicate test for every substance. A 

 method of indefinitely increasing the magnitude of minute 

 effects is indicated in the principle of action of Holtz's 



1 Address to the Royal Microscopical Society, Feb. 2, 1876. 



