EDITOR'S TABLE. 



495 



permanent results are at last arrived 

 at. Modern science arose from the 

 exhaustion of previous methods of 

 thought. The earlier pliilosophy spec- 

 ulated concerning Nature, and sought 

 after her truths in the depths of the 

 human mind. All that high genius and 

 varied intellectual power could do was 

 done, but to no purpose until the search- 

 ers for truth changed their attitude to 

 Nature, and began to inquire of her by 

 the simple and despised methods of ex- 

 perimental investigation. Dr. Priest- 

 ley, first of all men, approached the 

 problem of the constitution of the air 

 in this spirit, and was even compelled 

 to devise the contrivances by which 

 gaseous bodies could be manipulated. 

 He was on the right track, he had struck 

 the true method, and magnificently did 

 Nature reward his sagacity and his wis- 

 dom. Of course, for the Greeks or the 

 Romans, or the schoolmen of the mid- 

 dle ages, to have discovered oxygen, 

 would have been impossible. Only with 

 the decline of their modes of thought 

 could new methods arise, and only 

 through the apprenticeship of genera- 

 tions in the field of physical investiga- 

 tion were men prepared to pass to the 

 subtler search of the inner nature of 

 material things. The discovery of oxy- 

 gen, therefore, came in its due time 

 in the mental unfolding of humanity; 

 and while to Dr. Priestley undoubtedly 

 belongs the honor of having first dis- 

 closed and identified it, others would 

 quickly have plucked the ripened fruit if 

 he had not ; and in point of fact oxygen 

 was independently discovered shortly 

 after by the Swedish chemist Scheele, 

 who also discovered chlorine in 1774. 



But, if the discovery of oxygen 

 formed a great epoch in our advancing 

 knowledge of the constitution of Na- 

 ture, its influence was no less profound 

 upon the advance of chemical science. 

 We are accustomed to regard chemistry 

 as a kind of knowledge that is pecul- 

 iarly modern, but it is really very old, 

 and has had a long course of develop- 



ment. Liebig has stated that the com- 

 pletion of a science implies three stages 

 or operations. There are — 1. The ascer- 

 tainment of the properties of things by 

 observation and experiment; 2. The 

 bringing of them into relation by prin- 

 ciples or ideas ; and, 3. The application 

 of mathematics, or subjecting the phe- 

 nomena to the test of quantitative in- 

 vestigation. In chemistry, the first of 

 these stages runs back to antiquity. 

 The ancients knew many facts and 

 made many empirical experiments in 

 the arts which were of a chemical 

 nature. They knew seven metals — 

 gold, silver, mercury, copper, iron, tin, 

 and lead. They also knew various 

 preparations of zinc, antimony, and ar- 

 senic, and must have had a very consid- 

 erable knowledge of metallurgical pro- 

 cesses. They had also a knowledge of 

 glass, pottery, soap, dyes, pigments, 

 precious stones, asphalt, alum, starch, 

 beer, and many other substances which, 

 if not exact, was still so positive as to 

 guide them in the processes of manu- 

 facture. This kind of knowledge of the 

 properties of bodies must have gradual- 

 ly increased, and when we come down 

 to the time of Gheber, the Arabian, who 

 wrote a thousand years ago, we find 

 that this species of information had not 

 only greatly increased, but had become 

 more definitely chemical in character, 

 while laboratory operations were sys- 

 tematically practised. Gheber, for ex- 

 ample, knew the properties of com- 

 mon salt, potash, soda, saltpetre, am- 

 monia, copperas, borax, corrosive sub- 

 limate, oxide of copper, metallic ar- 

 senic, compounds of sulphur with the 

 metals, and the methods of preparing 

 sulphuric and nitric acids, aqua-regia, 

 litharge, and the operations of distilla- 

 tion, sublimation, smelting, and a great 

 number of chemical processes, as they 

 were practised down to the end of the 

 eighteenth century. By the alche- 

 mists these facts were immensely multi- 

 plied, forming a vast body of knowl- 

 edge concerning the chemical proper- 



