NOTES. 177 



be mixed with a little weak gum water, and then spread 

 over the paper, which must be dried without heat. 



Biniodide of mercury is said to be dimorphous ; that is, 

 is able to assume two different forms. 



( 10 ) Page 45. (( Prince Rupert's Drops." These are 

 made by pouring drops of melted green glass into cold 

 water. They were not, as is commonly supposed, invented 

 by Prince Rupert, but were first brought to England by 

 him in 1660. They excited a great deal of curiosity, and 

 were considered " a kind of miracle in nature. ". 



( n ) Page 46. Thick glass vessels. They are called 

 Proofs or Bologna phials. 



( 12 ) Page 47. Mica. A silicate of alumina and mag- 

 nesia. It has a bright metallic lustre, hence its name, 

 from micoj to shine. 



( 13 ) Page 48. Common salt or chloride of sodium 

 crystallises in the form of solid cubes, which aggregated 

 together, form a mass, which may be broken up into the 

 separate cubes. 



( 14 ) Page 49. Iceland or calc spar. Native carbonate 

 of lime in its primitive crystalline form. 



LECTURE IIL 



* 



( 15 ) Page 65. Solution of a salt. Acetate of soda. A 



solution saturated, or nearly so, at the boiling point, is 

 necessary, and it must be allowed to cool, and remain at 

 rest until the experiment is made. 



( 16 ) Page 71. Binoxide of nitrogen and hyponitrous 

 acid. Binoxide of nitrogen is formed when nitric acid 

 and a little water are added to some copper turnings. 



