72 



SCIENCE. 



[N. S. Vol. XX. Xo. 498. 



disease. Further, it is essential to the 

 manufacture of chloroform, and that this 

 calls for a large quantity of chlorine will 

 appear when it is stated that nearly nine 

 tenths of the weight of chloroform is chlo- 

 rine. Chloroform, which has been of such 

 inestimable value as an alleviator of pain, 

 can not be manufactured without chlorine, 

 and it could never have been discovered 

 without the previous discovery of chlorine. 



Finally, without attempting to give a fuU 

 account of all the uses to which chlorine 

 has been and is put for our benefit, let me 

 mention one more application, though in 

 doing so I may run the risk of leading some 

 of you to the conclusion that chlorine has 

 its dark side as well as its light. It is with 

 some misgivings that I venture to tell you 

 that chlorine has found extensive applica- 

 tion in the extraction of gold from its ores, 

 and as gold is held by some to be the root 

 of all evil, chlorine must, by the same 

 token, be regarded as particeps criminis. 

 A few years ago I visited the gold mines 

 in the Black Hills of South Dakota, and 

 there I spent some time in examining the 

 chlorination process. I could not help 

 thinking of Scheele and his simple experi- 

 ments that first brought chlorine to light. 

 I wondered whether, if he could see the ex- 

 tensive applications of that greenish-yellow 

 gas that first set him to weeping and cough- 

 ing — I wondered whether his satisfaction 

 in his work would be any greater than it 

 ihust have been when the discovery was 

 made. Compare the little room in the 

 apothecary shop, the simple apparatus, and 

 the apparent uselessness of the noxious gas 

 with the great factories, the complicated 

 machinery and the valuable applications 

 already mentioned, and it is evident that a 

 discovery that appears least promising 

 from the practical point of view may be the 

 beginning of the most valuable industries. 



Before leaving this part of my subject 

 let me take a mtich less important example 



than those already spoken of, but one that 

 comes nearer home. Nearly twenty-five 

 years ago in the laboratory under my 

 charge, an investigation was being carried 

 on that seemed as little likely to lead to 

 practical results as any that could well be 

 imagined. It woiild be quite out of the 

 question to explain what we were trying to 

 do. Any practical man would unhesitat- 

 ingly have condemned the work as being 

 utterly useless, and I may add that some 

 did condemn it. There was no hope, no 

 thought entertained by us that anything 

 practical would come of it. But lo! one 

 day it appeared that one of the substances 

 discovered in the course of the investiga- 

 tion is the sweetest thing on earth ; and then 

 it was shown that it can be taken into the 

 system without injury; and finally, that it 

 can be manufactured at such a price as to 

 furnish sweetness at a cheaper rate than it 

 is furnished by the sugar cane or the beet. 

 And soon a great demand for it was created, 

 and to-day it is manufactured in surprising 

 quantities and used extensively in all cor- 

 ners of the globe. Thousands have found 

 employment in the factories in which it is 

 now made, and it appears that in some Eu- 

 ropean countries the new substance has 

 become the sweetening agent of the poor, it 

 being sold in solution by the drop. 



It is unnecessary here to discuss the ques- 

 tion naturally suggested by the facts just 

 spoken of, whether the discovery of the 

 sweet substance has benefited the human 

 race. It would be extremely difficult, if 

 not impossible, to answer this question. 

 But whatever the answer, it is clear from 

 what has been said that the discovery was 

 of importance from the practical point of 

 view, and there was nothing originally in 

 the work to suggest the possibility of a 

 practical result in the sense in which the 

 word practical is commonly employed. 



This is the lesson that we learn over and 

 over again as we study the great industries. 



