July 15, 1904.] 



SCIENCE. 



71 



in many ways. If it is not enough for us 

 simply to gain a clearer insight into the 

 processes around us, if we must insist upon 

 more tangible reward, no doubt it could be 

 shown that the discovery of oxygen has 

 contributed largely to the material welfare 

 of mankind — not directly perhaps, but by 

 enlarging our knowledge of chemistry, so 

 that it may be said that most discoveries 

 made since 1774 have been in a way 

 consequences of the discovery of oxygen. 

 Indirect results are often of more value 

 than direct ones. 



But there is another discovery of 

 Scheele's that illustrates in another way 

 that a discovery that when made appears of 

 little or no practical value, may eventually 

 prove of immense practical value and be- 

 come the basis of a great industry. This is 

 the discovery of chlorine. Among the many 

 substances examined by Scheele was one 

 that is commonly known as black oxide of 

 manganese. This occurs in nature in large 

 quantity and has long been of interest to 

 chemists. Scheele treated this with about 

 everything he could lay his hands on, as 

 was his way. When muriatic acid, or, as 

 it was called by the older chemists, the 

 spirit of salt, was poured on the black oxide 

 of manganese, he noticed that something 

 unusual took place. He soon became aware 

 that a colored gas was given off, and that 

 this gas had other properties besides that of 

 color. It affected his eyes, nose, throat and 

 lungs in most disagreeable ways. Many of 

 those before me have had the experience of 

 inhaling a little of this gas. I hope no one 

 has inhaled much of it. It is one of the 

 most disagreeable things chemists and stu- 

 dents of chemistry have to deal with. And 

 it is not only disagreeable, it is extremely 

 poisonous. But Scheele did not stop his 

 work because it involved discomfort and 

 even danger. He persisted and carried it 

 to a successful issue, and when he stopped 

 he was able to give as satisfactory an ac- 



count of the now familiar chlorine as we 

 can give to-day. The investigation is a 

 model. It could not have been accom- 

 plished without the enthusiasm, the pa- 

 tience, the knowledge and the skill pos- 

 sessed ' by Scheele. No ordinary chemist 

 would have been ecjual to it. We shall not 

 overstate the case if we say that Scheele's 

 discovery of chlorine ranks with the most 

 important and the most valuable of chem- 

 ical discoveries. That of oxygen outranks 

 it certainly, but chlorine falls in line not 

 far behind. 



Now, why was this an important and a 

 valuable discovery? Primarily because it, 

 like the discovery of oxygen, though to a 

 less degree, aided chemists in their efforts 

 to understand chemistry and thus to put 

 them in a position to deal more intelli- 

 gently with chemical problems of all kinds.. 

 That statement may, once for all, be made 

 of every important chemical discovery. But 

 while Scheele had no thought of any prac- 

 tical uses to which chlorine could be put, 

 and his discovery was not at first regarded 

 as one with a practical bearing, it proved 

 eventually to be of the highest practical 

 value, and to-day it plays an exceedingly 

 important part in practical affairs. As is 

 well known, chlorine is the great bleacher, 

 and as such is used in enormous quantity, 

 especially for bleaching straw, paper and 

 dift'erent kinds of cloth. As it would be 

 expensive and inconvenient to transport a 

 gas, and especially such a gas as chlorine, 

 it is locked up, as it were, by causing it to 

 act iipon lime, and the 'chloride of lime' 

 or 'bleaching powder' thus formed, which 

 readily gives up its chlorine, is a most im- 

 portant article of commerce, many thou- 

 sands of tons being manufactured annually- 

 Then again chlorine is one of the most effi- 

 cient disinfectants, and as such it is finding- 

 more and more extensive use every year, 

 and is plainly contributing to the welfare 

 of man by interfering with the spread of 



