70 



SCIENCE. 



[N. S. Vol. XX. No. 498. 



know.' I am well aware that such answers 

 seem to show that the work is in fact of no 

 value, and that this is the impression that 

 my visitors carry away with them. Now I 

 do not propose to try to justify my own 

 work, nor to try to explain it. For the 

 most part it has had to deal with matters 

 that do not touch our daily lives, and there- 

 fore it can not be made interesting, not to 

 say intelligible. I shall, to be sure, show 

 you how one piece of work carried out 

 twenty years ago has become of world-wide 

 interest, though when it was carried out it 

 appeared as little likely to be of practical 

 value as anything ever done. But this is 

 anticipating. 



During the latter half of the last century 

 there lived in Sweden a poor apothecary 

 who, in his short life, probably did more to 

 enlarge our knowledge of chemistry than 

 any other man. Throughout his life he had 

 to contend with sickness and poverty. He 

 was obliged to carry on the business of an 

 apothecary in order to keep the wolf from 

 entering his house— he never succeeded in 

 keeping it from the door. His great delight 

 was to investigate things chemically, and to 

 find out all he could about them. It is 

 simply astounding to the chemist to find 

 how many discoveries of the highest impor- 

 tance he made. But I have not mentioned 

 his name. I refer to the immortal Scheele. 

 He died in the year 1786 at the age of 43, 

 yet he will always be remembered, and 

 those who know most of the work he did 

 will respect him most. 



Though Scheele was an apothecary, his 

 chemical work was not practical in the ordi- 

 nary sense, and it was no doubt often diffi- 

 cult for him to explain what he was doing. 

 His most important discovery was that of 

 oxygen — a discovery that was made at the 

 same time (1774) by the English clergy- 

 man, Priestley. Chemists know that this is 

 one of the most important discoveries ever 

 made in the field of chemistry, and, filled 



with this conviction, in 1874, one hundred 

 years after the discovery was made, the 

 chemists of the United States made a pil- 

 grimage to Northumberland on the Susque- 

 hanna to do honor to the memory of Priest- 

 ley, who there spent the last years of his 

 life. 



But why was this discovery so impor- 

 tant? Oxygen, to be sure, is the most 

 widely distributed and the most abundant 

 substance in and on the earth; it plays a 

 controlling part in the breathing of animals, 

 and in most of the changes that are taking 

 place upon the earth; a knowledge of it 

 and of the ways in which it acts has done 

 more than anything else to give chemists 

 an insight into chemical action in general; 

 and therefore has contributed more than 

 anything else to the development of chem- 

 istry. All this is no doubt true, but are 

 these results practical? Could we go out 

 into the world and form a company and 

 sell stock on the basis of such a discovery? 

 Or could the discoverer in any way realize 

 in cash? The average man of the world 

 would say: "No! there is nothing in it. 

 It may be well for a few men who have not 

 the power to compete with their fellow-men 

 in the busy marts to devote themselves to 

 such useless pursuits. Possibly something 

 may come of it in time, but better some- 

 thing practical, something that can be con- 

 verted into hard cash. That is the test, 

 and the only fair test by which we can 

 judge whether any particular piece of sci- 

 entific work is or is not of value. ' ' 



But I have already said that the discov- 

 ery of oxygen was the most important dis- 

 covery ever made in chemistry, and I might 

 have added, the most valuable. In what, 

 then, did its value consist? In the fact 

 that it led to a more intelligent working 

 with all things chemical. Operations that 

 had before this discovery appeared mys- 

 terious suddenly became clear, and every 

 one engaged in chemical work was helped 



