1818.] Sir Torbem Bergman. 335 



reagents- Though it contains a great deal of erroneous theory, 

 yet, as the experiments are all distinctly and numerically stated, 

 we have it in our power to strip them of the theory in which 

 they are involved, and to apply them to the present state of our 

 knowledge. They must have contributed very materially to 

 guide the subsequent investigations of chemists ; though the 

 numbers given by Bergman are not sufficiently precise to enable 

 us, from them alone, to deduce the composition of the metallic 

 oxides. 



19. On the Art of assaying in the humid Way. — This disser- 

 tation appeared likewise in 1780, ana is no less than a complete 

 treatise, explaining the method of analyzing the ores of all the 

 known metals. It was the first treatise of the kind that appeared, 

 and constituted the groundwork of all that has since been done. 

 It would be useless to examine it here. Almost every part of 

 the treatise has been improved upon ; almost every formula has 

 been modified or altered. But it must be at once obvious how 

 much the art of analysis owes to Bergman for this commence- 

 ment. 



20. On the Blow-pipe. — This paper had been sent in manu- 

 script to Baron Born in 1777, by whom it was published in 

 1779. It contains directions how to make experiments with 

 the blow-pipe, and gives a very particular account of the pheno- 

 mena exhibited by the different stones, metals, and ores, when 

 heated by the blow-pipe, either alone, or mixed with the different 

 fluxes. Since that time, the use of the blow-pipe has been still 

 further improved by Assessor Gahn. His essay on the subject, 

 published in a preceding volume of the Annals of Philosophy, 

 we recommend to the careful study of every person who wishes 

 to become expert in the use of this very important instrument of 

 investigation. 



21. On the Analysis of Iron. — This important dissertation, 

 published in 1781, contains the experiments, by means of which 

 the difference between iron, cast iron, and steel, was accounted 

 for. Bergman first detected the presence of plumbago in cast 

 iron and steel, and he first showed that iron yields more hydro- 

 gen gas than either cast iron or steel. The experiments were 

 very numerous ; and as far as they went, they are sufficiently 

 satisfactory. 



22. On the Cause of the Brittleness of Cold Short Iron. — 

 This paper, like the last, was published in 1781. When cold 

 short iron is dissolved in sulphuric acid, a white powder remains, 

 which, when heated with charcoal, was reduced to a metallic 

 button. To this substance Bergman gave the name of siderum; 

 and he showed that when added to iron it renders it cold short. 

 It was soon after shown, that this supposed new metal is merely 

 a phosphuret of iron. Hence it has been inferred, that iron is 

 rendered cold short by uniting with phosphorus. 



This paper has been already carried to such a length, that it 

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