4 Biographical Account of J. G. Gahn. [July, 



the poet, in revolving it again and again in his mind, year after 

 year. Yet advantageous as the severe rule of " nonum prematur 

 in annum " may be to poets and their productions, it is by no 

 means applicable to philosophers and their discoveries ; and if 

 the friends of Gahn had but been more generous in acknowledg- 

 ing whence they drew their own information, we must have 

 been more heartily grateful to them for communicating it to 

 others, and thereby, not unfrequently, securing a benefit which 

 might else have perished. 



Besides those discoveries which resulted from the investiga- 

 tions of Gahn, he conferred a favour of yet greater practical 

 importance on science, in the improvements which he made as 

 the means of prosecuting research. During his youth, the blow- 

 pipe was little used by men of science, and its advantages were 

 less understood. That instrument, by which they are now ena- 

 bled to make microscopic analyses in the dry way, with a degree 

 of precision then wholly unexpected, was in its rude state at that 

 period, more used by the mechanic than by the chemist. Cron- 

 stedt and Engerstrom first discovered its importance in distin- 

 guishing minerals by their various degrees of fusibility, and 

 their several habitudes with fluxes. Next, Bergmann, by his 

 excellent Dissertation de Tubo Ferruminatorio, extended the 

 knowledge of the instrument more widely, and explained its 

 uses more fully to the learned world. Gahn had been employed 

 by this philosopher to make the greater part of the experiments 

 detailed in the Dissertation, and, from that period, the improve- 

 ment of every thing connected with the nature or management 

 of the blowpipe, became one of his most favourite occupations. 

 He enlarged, and at the same time defined, the uses of the seve- 

 ral reagents ; he added some new ones of great importance to 

 their number; he invented or improved the various apparatus 

 accompanying the instrument ; and by his almost intuitive saga- 

 city in detecting the characteristics both of simple bodies and 

 of compound minerals, he was enabled to point out at once the 

 plainest and most efficacious means by which they may be dis- 

 covered and discriminated. A concise summary of directions 

 for using the instrument was drawn up by him, and published 

 in the second volume of Berzelius's Elements of Chemistry. 



Another important facility contributed by Gahn to the prose- 

 cution of research, deserves to be classed with that just men- 

 tioned, and is, perhaps, scarcely inferior to it in value. This 

 was the invention of a balance, not more remarkable for its 

 extreme delicacy, than for the simplicity of its construction. 

 The latter quality it possesses in so remarkable a degree, that it 

 may be easily constructed by any workman of even very mode- 

 rate qualifications ; and thus this elegant and indispensable 

 instrument was placed generally within the reach of all. Avery 

 copious description of it was written out by the inventor, a few 



