OCTOBEE 26, 1900.] 



SCIENCE. 



637 



examination of minerals, and it was he who 

 first used platinum wire and cobalt solution 

 in connection with blowpipe analysis. The 

 methods emploj^ed by Gahn were further 

 developed by his friend Berzelius (1779- 

 1848), who gave much attention to the 

 matter, and who with great skill and pa- 

 tience gradually worked out a comjDlete 

 scheme of blowpipe analj'sis, and published 

 it in a pamphlet, entitled ' Ueber die An. 

 wendung des Lothrohrs,' which appeared 

 in 1820. After the publication of this work 

 blowpipe analysis rapidly came into general 

 use in England, France and Germany, and 

 the scheme devised by Berzelius is essen- 

 tially that employed at the present day. 



Indeed, the only notable additions to the 

 method of analysis in the dry way since the 

 time of Berzelius are the development of 

 flame reactions, which Bunsen worked out 

 with such characteristic skill and ingenuity, 

 and the introduction of the spectroscope. 



The necessity for some process other than 

 that of analysis in the dry way seems, in 

 the first instance, to have arisen in quite 

 early times in connection with the exami- 

 nation of drugs, not only on account of the 

 necessity for discovering their constituents, 

 but also as a means of determining whether 

 they were adulterated. In such cases analy- 

 sis in the dry way was obviously unsuitable, 

 and" experience soon showed that the only 

 way to arrive at the desired result was to 

 treat the substance under examination with 

 aqueous solutions of definite substances, the 

 first reagent apparently being a decoction 

 of gallnuts, which is described by Pliny as 

 being employed in detecting adulteration 

 with green vitriol. 



The progress made in connection with 

 wet analysis was, however, exceedingly 

 slow, largely owing to the lack of reagents • 

 but as these were gradually discovered wet 

 analysis rapidlj' developed, especially in the 

 hands of Tachenius, Scheele, Boyle, Hoif- 

 man, Margraf and Bergmann. Boyle (1626- 



1691) especially had an extensive knowl" 

 edge of reagents and their application; and, 

 indeed, it was Boyle who first introduced 

 the word ' analysis ' for those operations by 

 which substances maj' be recognized in the 

 presence of one another. Boyle knew how 

 to test for silver with hydrochloric acid, for 

 calcium salts with sulphuric acid, and for 

 copper by the blue solution produced by 

 ammonia. 



Margraf (1709-1782) introduced prus- 

 siate of potash for the detection of iron, and 

 Bergmann (1735-1784) not only introduced 

 new reagents and new methods for decom- 

 posing minerals and refractory substances, 

 such as fusion with potash, digestion with 

 nitric acid or hydrochloric acid, but he also 

 was the first to suggest the application of 

 tests in a systematic way, and, indeed, the 

 method of analysis which he developed is 

 on much the same lines as that in use at 

 the present day. He paid special attention 

 to the qualitative analysis of minerals, and 

 gave careful instructions for the analysis 

 of gold, platinum, silver, lead, copper, zinc 

 and other ores. The work of Scheele 

 (1742-1786) had indirectly a great influ- 

 ence on qualitative analysis, as, although 

 he did not give a general systematic method 

 of procedure in the analysis of substances 

 of unknown composition, yet the methods 

 which he employed in the examination of 

 new substances were so original and exact 

 as to remain models of how qualitative 

 analysis shall be conducted. 



Great strides in analytical chemistry in 

 the wet way were made through the work 

 of Berzelius, who, by the discovery of new 

 methods, such as the decomposition of sili- 

 cates by hydrofluoric acid and the introduc- 

 tion of new tests, greatly advanced the art. 

 He paid special attention to perfecting the 

 methods of analysis of mineral waters, and 

 these researches as well as his work on 

 ores, and particularly his investigation of 

 platinum ores, stamp Berzelius as one of 



