222 Notices respecting New Books. 



the manipulations employed and the difficulties overcome would ex- 

 ceed the limits of a lecture." Well knowing how valuable every 

 minute circumstance is to the chemist, Dr. Paris searched into the 

 archives of the Institution ; the result of the examination of the 

 Laboratory Register, we shall give in Dr. Paris's words: " It appears 

 from this register that Davy commenced his inquiries into the com- 

 position of potash on the 16th, and obtained his great result on the 

 I9th of October, 1807 *. His first experiments, however, evidently 

 did not suggest the truth : he does not appear to have suspected the 

 nature of the alkaline base until his last experiment, when the truth 

 flashed upon him in the full blaze of discovery. His first note, 

 dated the 16th, leads us to infer that he acted on a solid piece of 

 potash, under the surface of alcohol, and several other liquids in 

 which the alkali was not soluble ; and that he obtained gaseous 

 matter, which lie called at the moment ' alkullgen gas,' and which he 

 appears to have examined most closely, without arriving at any con- 

 clusion as to its nature. On the following day, he for the first time 

 would seem to have developed potassium by electric action on potash 

 under oil of turpentine, for the note records the fact of ' the globules 

 giving out gas by water, which gas burnt in contact with air ;' and 

 then follows a query, ' Does (7 (the matter of the globules) not form 

 gaseous compounds with ijether, alcohol, and the oils V Here, then, 

 he evidently imagined, that the matter of the globules, which he had 

 never obtained from potash, except when acted upon under oil of 

 turpentine, had formed gaseous compounds with the aether, alcohol 

 and oils, in his previous experiments, and given origin to that which 

 he had termed ' alkaligen gas.' " 



" He then leaves the consideration of this gas, and attacks the un- 

 known globules, which probably did not present any metallic ap- 

 pearance under the circumstances in which he first saw them, for 

 they must have been as minute as grains of sand. I rather think 

 that he commenced his examination by introducing a globule of 

 mercury, and uniting it with a globule of the unknown substance ; 

 for his note says, 'Action of the substance on mercury, forms with 

 it a solid amalgam, which soon loses its alkaligen in the air ;' and 

 from the note which succeeds, he evidently considered this alkaligen 

 (potassium) as volatile, as he says " it soon flies off on exposure to 

 the air." 



" October 19. — It is probable that in consequence of the property 

 which the unknown substance displayed of amalgamating with mer- 

 cury, he devised his experiment of the 19th. He took a small glass 

 tube, about the size and shape of a thimble, into which he fused a 

 platinum wire, and passed it through the closed end. He then put 

 a piece of pure potash into this tube, and fused it into a mass about 

 the wire, so as entirely to defend it from the mercury afterwards to 

 be used. When cold, the potash was solid, but containing moist- 

 ure enough to give it a conducting power ; he then filled the rest of 

 the tube with mercury, and inverted it over the trough ; the appa- 



» On tiic haiiic day he decomposed soda, with somewhat different phae- 

 noinena. 



ratus 



