10 On the Decomposition and Composition 



IV. On the Properties and Nature of the Basis of Potash* 

 After I had detected the bases of the fixed alkalis, I had 

 considerable difficulty to preserve and confine them so as to 

 examine their properties, and submit them .to experiments ; 

 for, like the alkahests imagined by the alchemists, they 

 acted more or less upon almost every body to which they 

 were exposed. 



The fluid substance amongst all those I have tried, on 

 which I find they have least effect, is recently distilled naph- 

 tha. — In this material, when excluded from the air, they 

 remain for many days without considerably changing, and 

 their physical properties may be easily examined in the at- 

 mosphere when thev are covered by a thin film of it. 



The basis of potash at 60° Fahrenheit, the temperature in 

 which I first. examined it, appeared, as I have already men- 

 tioned, in small globules possessing the metallic lustre* ' 

 opacitv, and general appearance of mercury; so that when 

 a globule of mercury was placed near a globule of the pe- 

 culiar substance, it was not possible to detect a difference 

 by the eye. 



At 60° Fahrenheit it is however only imperfeetlv fluid, 

 for it does not readily run into a globule when its shape is 

 altered; at 20° it becomes more fluid; and at 100° its flu- 

 idity is perfect, so that different globules may be easily made 

 to run into one. At 50° Fahrenheit it becomes a soft and 

 malleable solid, which has the lustre of polished silver; and 

 at about the freezing point of water it becomes harder and 

 brittle, and when broken in fragments exhibits a crystallized 

 texture, which in the microscope se°ms composed of beautiful 

 facets of a perfect whiteness and high metallic splendour. 



To be converted into vapour, it requires a temperature 

 approaching that of the red heat ; and when the experiment 

 is conducted under proper circumstances, it is found unal- 

 tered after distillation. 



It is a perfect conductor of electricity. When a spark 

 from the Voltaic battery of 100 of six inches is taken upon 

 a large globule m the atmosphere, the light is green, and 

 combustion takes place at the point of contact only. When 



a small 



