KLAPROTH i8i 



the investigation. The agreement of the sum of the weights 

 of the components found, with the weight of substance taken 

 for investigation, now gave a measure of the accuracy of the 

 investigation, and of the trustworthiness of the methods used. 

 The progress since made by analytical chemistry, the dis- 

 covery of many new substances, depends solely upon this 

 manner of carrying out and communicating investigations, 

 inasmuch as too great a departure of the weight of the com- 

 ponents from that of the substance taken can only be caused 

 by a defective method or by the neglect of an unknown com- 

 ponent still contained in the substance.-*^ 



Thus Klaproth himself became above all an essential 

 improver of the methods of quantitative chemistry, which 

 enabled him to discover mistakes made by others, and which 

 often brought him in touch with Scheele's endeavours of like 

 nature. He also became the discoverer of a number of 

 hitherto unknown elements; thus in 1782 of tellurium, in 

 1789 of uranium in pitchblende, and of zirconia as a special 

 substance; in 1793 he undoubtedly separated strontia from 

 baryta; in 1795 he discovered titanium, and in 1803 cerium. 

 His methods of exact research enabled many of his successors 

 in the next fifty years to effect similar advances. In par- 

 ticular, the gradual recognition of the remaining elements, so 

 far as they are not present in all too small amount in terres- 

 trial substances, was realised in this way. An entirely new 

 method of finding the presence of elements present only in 

 traces was first given us in i860 by Bunsen and Kirchhoff's 

 discovery of spectrum analysis. Klaproth's achievements 

 received as much recognition as was possible in his country. 

 In 1809, at the age of sixty-six, he was made professor of 

 chemistry at the newly founded university of Berlin, after he 

 had already taught chemistry for several years previously at 

 the Artillery College. He died at the age of seventy-four. 



1 For further information regarding Klaproth see Encyclopaedia Brit- 

 annica. Art. Klaproth. 



