266 Wells & Foote — One Hundred Years of Chemistry. 



determining alkalies in minerals (16, 53), a method which 

 in its final form (1, 269, 1871) is the best ever devised for 

 the purpose. He also described (15, 94, 1853) a very 

 useful method, still largely used in analytical work, for 

 destroying ammonium salts by means of aqua regia. 

 Carey Lea (42, 109, 1866) described the well-known test 

 for iodides by means of potassium dichromate. F. W. 

 Clarke (49, 48, 1870) showed that antimony and arsenic 

 could be quantitatively separated from tin by the pre- 

 cipitation of the sulphides in the presence of oxalic acid. 

 In 1864 Wolcott Gibbs (37, 346) began an important 

 series of analytical notes from the Lawrence Scientific 

 School, and he worked out later many difficult analytical 

 problems, particularly in connection with his extensive 

 researches upon the complex inorganic acids. 



From 1850 on, Brush and his students made many 

 important investigations upon minerals, and from 1877 

 Penfield (13, 425), beginning with an analysis of a new 

 mineral from Branchville, Connecticut, described by 

 Brush and E. S. Dana, displayed remarkable skill and 

 industry in this kind of work. Both of the writers of 

 this article were fortunate in being associated with Pen- 

 field in some of his researches upon minerals and one of 

 us began as he did with the Branchville work. It is 

 probably fair to say that Penfield did the most accurate 

 work in mineral analysis that has ever been accom- 

 plished, and that he was similarly successful in crystal- 

 lography and other physical branches of mineralogy. 



The American analytical investigations that have been 

 mentioned were all published in the Journal, with the 

 exception of a part of Gibbs 's work. Many other Amer- 

 ican workers at mineral analysis might be alluded to 

 here, but only the excellent work of a number of chemists 

 in the United States Geological Survey will be mentioned. 

 Among these Hillebrand deserves particular praise for 

 the extent of his investigations and for his careful 

 researches in improving the methods of rock analysis. 



To our own Professor Gooch especial praise must be 

 accorded for the very large number of analytical methods 

 that have been devised, or critically studied, by him and 

 his students, and for the excellent quality of this work. 

 The publications in the Journal from his laboratory 

 began in 1890 (39, 188), and the extraordinary extent of 

 this work is shown bv the fact that the three hundredth 



