84 An Inquiry concerning the 



of charcoal which had been previously boiled several 

 hours in a large quantity of distilled water, and which 

 were introduced wet and hot into the tube, and imme- 

 diately covered by the solution, to prevent them from 

 imbibing any air; and in different experiments the 

 solution was used of different degrees of strength. 



I plainly perceived that the experiment succeeded 

 best that is to say, that the gold was soonest revived 

 in those cases in which the solution was most diluted: 

 one of the experiments, however, and which succeeded 

 perfectly, was made with the solution so much con- 

 densed that it was nearly at the point at which it 

 became disposed to crystallize.* 



On examining with a good microscope the particles 

 of revived gold which remained attached to the surface 

 of the charcoal after it had been dried, I found them 

 to consist of an infinite number of small scales, sepa- 

 rated from each other, not very highly polished, but 

 possessing the true metallic splendour, and a very deep 

 and rich gold colour. 



The gold which attached itself to the inside of the 

 glass tube was in the form of a ring, about iV of an 

 inch wide (badly defined, however, below), and adhered 

 to the glass with so much obstinacy as not to be re- 

 moved by rinsing out the tube a great number of 

 times with water. It had, as has already been observed, 

 a very high polish, when seen by reflected light. 



Those who enter into the spirit of these investiga- 

 tions will easily imagine how impatient I must have 



* This agrees perfectly with the results of similar experiments made by the 

 ingenious and lively Mrs. Fulhame. (See her Essay on Combustion, page 124.) 



It was on reading her book that I was induced to engage in these investiga- 

 tions ; and it was by her experiments that most of the foregoing experiments 

 were suggested. 



